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1. downloaded from fib ommolkcefab ir Team LiB W well formed A term describing a document that conforms to the syntax rules of XML For example in a well formed document tags have proper delimiters an end tag follows a start tag and elements dc not overlap working draft An in progress version of a specification produced by a standards body working group A working draft often changes substantially before the recommendation phase Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB X XHTML Exntensible Hyptertext Markup Language XHTML is a reformulation of HTML 4 as an XML application The XHTML DTDs define elements and attributes as they are in HTML 4 01 XHTML Basic is a smaller subset of XHTML but otherwise the XHTML 1 x specifications made no changes to the actual vocabulary XHTML 2 0 adds new features to the XHTML vocabulary See alsoHTML hypertext markup XML declaration The first element of a document prolog declaring that the document is an XML document and the XML version it conforms to Most documents will have this XML declaration as their first line lt lt sm version e0 XLink XML Linking Language Specifies elements that can be used in XML documents to create and describe links between resources XLink provides for more robust linking relationships than do the simple hyperlinks in HTML XML processor A generic term for
2. gt Because the parameter entity optional stuff is defined with the keyword INCLUDE the declarations in the marked section will be used Ifoptional stuff had been defined to be IGNORE the declarations would have been ignored in the document This technique is especially powerful when you declare the entity inside a document subset In the next example our DTD declares a general entity that is calleddisclaimer The actual value of the entity depends on whether use disclaimer has been set to INCLUDE lt Suse disclaimer lt ENTITY disclaimer lt p gt This is Beta software We can t promise it is free of bugs lt p gt gt gt lt 1 ENTITY disclaimer gt In documents where you want to include a disclaimer it s a simple step to declare the switching entity in the internal subset lt xml version 1 0 gt lt DOCTYPE manual SYSTEM manual dtd lt ENTITY use disclaimer IGNORE gt IE manual lt title gt User Guide for Techno Wuzzy lt title gt amp disclaimer downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir In this example the entity use disclaimer IS set to IGNORE so the disclaimer is declared as an empty string and the document s text will not contain a disclaimer This is a simple example of customizing a DTD using conditional sections and parameter entities Now returning to our previous problem of overriding element or attribute declarations here is ho
3. xsl text crgo xsl apply templates select deposit 1 payment information gt n P lt xsl text gt Expenditures from xsl text lt xsl value of select child 1 date gt lt xsl text gt until lt xsl text gt xsl value of select child last date lt xsl text gt ranked from highest to lowest lt xsl text gt ens xsl apply templates select payment gt xsl sort data type number order descending select amount xsl apply templates lt body gt downloaded from lib ommolketab ir downloaded from lib ommolketab ir nml lt xsl template gt And finally we ll display the account balance We ll usenumber to calculate the sum of the transactions Two sum terms are necessary one for the payment total and one for the income total Then we ll subtract the total payment from the total income To make it clear whether the user is in debt or not we ll color code the calculated result and print a warning if it s negative Here is the template lt xsl template match checkbook gt lt M Le lt head gt lt body gt lt l Income information gt liso lt xsl text gt Income from lt xsl text gt lt xsl value of select child 1 date gt lt xsl text gt until lt xsl text gt lt xsl value of select child last date gt lt xsl text gt lt xsl text gt cg xsl apply templates select deposit gt 1 payment informat
4. downloaded from fib ommolkcefab ir Another kind of linked object is an invisible marker It has no overt function in the flow other than to me location so that later when generating an index you can calculate a page number or create a hyperlink Index items often span a range of pages so you might want to capture the rangewith two markers one the beginning and one at the end 3 2 6 XHTML Good old HTML is the markup language we are all familiar with Simple pretty easy to learn it has turn the Internet from an obscure plaything of a few academics to a must have utility for everyone Its succe can be attributed to the good enough principle of web design It s good enough to model almost any si document as long as you don t mind its limitations single column format flat structure and lack of pag oriented features The simplicity that made HTML so popular with novice publishers is frustrating to professionals Graphic designers crave better page layout capability and stylesheet granularity Web developers want better structure and navigation Librarians and researchers want more detailed metadata and search capability Users with special needs want more localization and customization Poor HTML has been pushed to do fe more than it was ever designed to do None of this makes HTML a bad markup language It will not go away anytime soon because it does its well It is a basic markup language for electronic display and cross document li
5. rgb 02559 0 00 00 lime rgb 0 65 rgb 0 160 0 002000 maroon rgb 70 rgb 176 0 60 00050 navy rgb 08 rgi UD 15D 000040 olive gb 65 robi 160 160 0 202000 purple rgb 65 rgb L605 0 160 20000 red rgb 100 03 32 rgb 255 0 80 0050 m rol 20 904 904 rgb pee pd a0dod0 teal rgb 0 65 100 rgb ori 0295 amp 00a0 f white rgb 100 100 100 rgi 255 255 255 terere yellow rgb 100 100 03 robi 255 255 0 00 5 4 6 Generated Text 3e Automatically generating text is an important capability of stylesheets We have seen an example where a warning sidebar was created with an automatically generated WARNING header The general form of a text generating property is contents SCrIDOJI SDCPLImOS Each string is either a quoted value like WARNING or a function that creates text Some of these text creating functions are url locator This function opens a file at a URL given by 1ecator and inserts the contents of the file at that point in the text This is useful for including boilerplate text attr attname This function inserts the value of an attribute with nameattname counter name This useful function reads the value of an internal counter with the labelname and converts it to text downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 5 4 6 1 Counters Counters in CSS are variables that hold nume
6. Figure 5 3 A stylesheet used to help produce a formatted document The software that uses a stylesheet to generate formatted output is astylesheet processor As it reads the XML document it keeps consulting the stylesheet to find rules to apply to elements For each element there may be multiple rules that match so the processor may apply them all or it may just try to find one that is the best fit Matching rules to elements can be a complex process in writing a stylesheet downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 5 1 2 2 Client and server side processing The result of this processing is either a generated display or another document The first case is what you would see in a web browser on screen or a printout from the browser It s a device dependent result created on the client end of the transaction Client side processing like this takes the load off of the server making information propagate faster It also gives the end user more control over the appearance by being able to override some style settings The other kind of output from a style processor is a new document XSLT which we will explore in Chapter 7 is such a stylesheet language This sort of process is also known as atransformation because it effectively transforms the original document into a different form Transformations can be performed on either the server or the client end before or during the transaction For example a Do
7. You may wonder what happens when the for each directive fails to match any nodes The answer is nothing The XSLT processor never enters the region of the element and instead just continues on with the template There is no or else contingency in or each but you can get that functionality by using if and choose constructs covered later in the chapter 7 5 5 Named Templates All the template rules we have seenso far are specified by their match patterns They are accessible only by the XSLT engine s template matching facility Sometimes however you may find it more convenient to create a named template to which you can direct processing manually The concept is similar to defining functions in programming You set aside a block of code and give it a name Later you can reference that function and pass it data through arguments This makes your code simpler and easier to read overall and functions keep frequently accessed code in one place for easier maintenance These same benefits are available in your XSLT stylesheet through named templates A named template is like any other template except that it has aname attribute You can use this with a match attribute or in place of one Its value is a name a qualified name to be specific that uniquely identifies the template 7 5 5 1 The call template directive To direct processing to this template use the directivecall template identifying it with a name attribute For example lt
8. and amp that cannot be used directly in the content of an XML document because they would conflict with the markup See alsoentity reference markup entity reference A special string that refers to an entity indicated by a startings amp and an ending semicolon Entity references occur in text and are parsed by the XML processor See alsoentity external entity An entity that refers to another document See also entity file URL downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir external subset A group of declarations comprising all or part of a document type definition that is stored in an external entity and referenced from a document s DTD using a public or system identifier See also document DTD Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB E FPI formal public identifier A public identifier that conforms to the specification of public identifiers in ISO 8879 An FPI contains information such as the class of the resource I e a DTD its author and language See also catalog external entity fragment identifier An extension of a URL that identifies a location inside an HTML document by a named element See also URL Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB H HTML Hypertext Markup Language The markup language used to create docu
9. ar coraned te dekar an rd In vien christe wid tlc high i se mE gran m Tor reta lodirecu nce ie ers Ditema Dana e Pont weight bold fant pize Liptr Hioke hese ecaypfoaleus lz atylel can CSS has a lot more to it than the few properties we ve seen here More and more these features are being implemented in browsers allowing web designers more freedom to express themselves Some things we haven t talked about are the interesting properties coming in CSS level 3 These include alternative media formats such as speech synthesis and printed page You will have much better control of your document in these forms as well as on screen As useful as CSS can be it is still limited in many ways We mentioned the problem of working with elements out of order CSS can t jump ahead to grab an element at the end of the document for example Its processing path is fixed Lucky for us there is another option XSLT and XSL FO bring t the table much more powerful formatting allowing you incredible freedom to control the path of processing Get ready because they are the subjects of the next two chapters Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 6 XPath and XPointer XML has often been compared to a database because of the way it packages information for easy retrieval Ignoring the obvious issues of speed and optimization this isn t a bad analogy Element names
10. downloaded from fib ommolkcefab ir o 909 e o PUBLIC public identifier public identifier o O o Here is an example with a public identifier lt DOCTYPE html PUBLIC W3C DID HTML 3 2 EN http www w3 org TR HTML html dtd 2 3 2 2 Declarations Declarations are pieces of information needed to assemble and validate the document The XML parser f reads declarations from the external subset given by the system or public identifier then reads declarations from the internal subset the portion in square brackets in the order they appear In this chapter will only talk about what goes in the internal subset leaving the external subset for Chapter There are several kinds of declarations Some have to do with validation describing what an element m or may not contain again will go over these in Chapter 3 Another kind is the entity declaration whi creates a named piece of XML that can be inserted anywhere in the document The form of an entity declaration is shown in Figure 2 7 It begins with the delimiter ENTITY 1 Is followed by a name 2 then a value or identifier 3 and the closing delimiter gt 4 Figure 2 7 Form of an entity declaration The value or identifier portion may be a system identifier or public identifier using the same forms show in Figure 2 5 and Figure 2 6 This associates a name with a piece of XML in a file outside of the docume That segment of XML becomes an entity
11. downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 8 1 How It Works Unlike CSS which simply appliesstyles directly to elements in a single pass through the document XSL gives you the opportunity to do major reorganization of your document This capability comes at the cost of simplicity To ease the burden on developers the designers of XSL have split the process into two parts transformation and formatting The transformation alters the structure of the input document and adds presentational information in a hybrid format composed of formatting objects Aformatting object is a container for content that associates styles and rendering instructions with the content It is compact and easy for a person to understand The formatting objects are arranged in a tree that retains structure used in building the final presentation The result of this transformation is a temporary file that you feed to an XSL FO formatter Through a complex series of steps the formatter calculates the final geometry and appearance of the presentation and churns out a file suitable for printing or viewing on a screen When it s finished the formatting objects are flushed from memory and you can discard the temporary FO file It is important to understand that you are not meant to write your own XSL FO markup Make all of your stylistic corrections in the XSLT stylesheet and let the tools do the rest 8 1 1 Formatting In
12. entry 1d 44456 gt lt surname gt Mentary lt surname gt lt firstname gt Rudy lt firstname gt lt town gt Simpleton lt town gt lt street gt 123 Bushwack Ln lt street gt lt phone gt 555 1234 lt phone gt lt entry gt entry 1d 44457 gt lt surname gt Chains lt surname gt lt firstname gt Allison lt firstname gt lt town gt Simpleton lt town gt lt street gt 999 Leafy Rd lt street gt phone 555 4321 phone entry telephone book By default the transformation processes each node in the order it appears in the document So the entry with id 44456 is output before id 44457 Obviously that would not be in alphabetical order so we need to sort the results somehow It just so happens that we can do this with an element called sort Here s how the document element s rule might look lt xsl template match telephone book gt xsl apply templates lt x5l sort SelecbS Low ckalesort selecretsurpname J xsl sort select firstname gt xsl apply templates downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt xsl template gt There are three sorting axes here First all the results are sorted by town Next the entries are sorted by surname Finally the entries are sorted by first name 7 6 7 Handling Whitespace Character data from the source tree is not generally normalized You can force the XSLT engine to strip space of selected elemen
13. lt fo page sequence master gt lt fo simple page master master name basic gt Ele 12s lt fo simple page master gt fo layout master set Since this is a common occurrence in simple designs you can leave out thesingle page master reference Which will imply the simplest possible sequence that of using one page master throughout The last and most complex type is repeatable page master alternatives lt defines a set of page master references with conditions for use For example you might want to have a differentiate between odd numbered recto and even numbered verso pages You can accomplish that effect with this page sequence croslavout master ser rto page sequence master lt fo repeatable page master alternatives gt lt fo conditional page master reference odd or even even master reference verso gt lt fo conditional page master reference odd or even odd master reference recto gt lt fo repeatable page master alternatives gt lt fo page sequence master gt lt fo simple page master master name verso gt lt lao downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt fo simple page master gt lt fo simple page master master name recto gt CL qw SS lt fo simple page master gt fo layout master set The conditional page master reference object is similar to single page master reference except that it has to fulfill a precondition to be used T
14. lt xs complexType name telegramtype lt xS sequence gt lt xs element name to type texttype gt lt xs element name from type texttype gt lt xs element name subject type texttype gt lt xs element name graphic type graphictype gt lt xs element name message type messagetype gt lt xs sequence gt xs attribute name pri type xs token gt lt xs complexType gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir xs simpleType name texttype gt xs restriction base xs string xs minLength value 1 gt lt xs restriction gt lt xs simpleType gt xs complexType name graphictype gt xs attribute name fileref type xs anyURI use required xs complexType xs complexType name messagetype mixed true gt xs choice minOccurs 0 maxOccurs unbounded gt lt xs element name emphasis type xs string gt lt xs element name name type xs string lt xs element name villain type xs string lt xs choice gt lt xs complexType gt lt xs schema gt So there are several levels of quality assuranceavailable in XML You can rest assured that your data is in a good state if you ve validated it 1 3 4 Support Multiple Languages XML wants to be useful to the widest possible community Things that have limited other markup languages from worldwide acceptance have been reworked The character set for starters
15. v3 villain lt name gt Doctor Evil lt name gt lt evil gt 6 lt evil gt lt intelligence gt 6 lt intelligence gt lt fashion gt 8 lt fashion gt lt villain gt raspsonsgeJTrsashrono lt willsq07 y villain lt name gt Scorpius lt name gt lt evil gt 9 lt evil gt lt intelligence gt 9 lt intelligence gt In this arrangement you can search quickly for records using theid as a primary key The content field still contains the content of each record as XML An advantage to keeping XML in a field is that you can add or remove elements any time without affecting the rest of the database A disadvantage to storing data in elements instead of fields is that you can t use the database s built in functionality such as searching on one of those fields or checking the validity of an element s value If you only need to search for a record using the ia and will validate the content on your own then this method works well A good application of this arrangement is a web content management system where the content is HTML to be served as a page Another way to combine the performance of databases with the convenience of XML is to convert database queries into XML You store the data exclusively in the database s native field types but when you retrieve information a piece of code translates it into XML in real time For example someone may write a SAX driver tailored to the particular brand of database you are using It would be s
16. C D E F G EH 1 J K L EM N O P Q R S T U V W X qualifying element names with prefixes quality control schemas validation querying standards Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E F G H 1 J K L EM N O P IQ IR S T U IV W X ranges constructing covering searching strings RDF Resource Description Framework recommendation formal W3C standards process records recursive definitions red green and blue RGB redirecting XSLT processing references character encodings class interface cross references entities modularity numeric refined formatting object tree refinement regions relationships relative location terms relative measurements relative paths relative URLs RELAX NG 2nd 3rd attributes data typing elements modularity name classes named patterns namespaces remote resources rendering formatting repetition of elements Resource Description Framework RDF resources books local online remote standards organizations tools result trees fragment expressions downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir results XSL FO retrieving data nodes returning points RGB red green and blue roles root element root elements 2nd root node root nodes rows characters r
17. P IQ R S T U V W X lang function languages codes stylesheets layout objects leafs length mixed content entities levels of validation limitations of programming of stylesheets line height linked objects linking documents standards links actuating lists XSL FO little endian architecture local names local resources locating location paths expressions Boolean node set number strings shortcuts location sets location steps logical structure low information content Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB AT B C D E F EG H 1 DJ K L M EN O IP Q R S ET U V W X management DTDs markup mapping dictionaries flows margins 2nd 3rd 4th See also spacing properties markup 2nd 3rd CDATA sections comments events language toolkit languages managing mixed content entities processing instructions standards streams tags transformation default rules elements executing formatting history of matching nodes modularity naming overview of precedence redirecting templates masters DocBook sequences MathML Mathematical Markup Language 2nd standards media documents describing types merging grammars messages formatting metadata document prologs narrative documents Microsoft Internet Explorer MI ME Multipurpose Internet Mail Extensions downloade
18. People who download copyrighted materials from the Internet should have then computers destroyed said Senator Orrin Hatch R Utah In a recent statement In a sweet twist of irony Wired News reported that the Senators own web site was guilty of using unlicensed soltware to generate menus It is possible to make the current block inherit the aforementioned properties from its parent with the value inherit 8 4 3 2 Background properties There are many options to alter the background of a block You can set a color make the backgrounc transparent or display a graphic Listed below are the background properties along with their allowed values default values in bold background attachment Allows the background image to be scrolled along with the foreground of the object Values scroll fixed inherit Da kgEOounde color Sets the background to some named color or makes it transparent Values color transparent inherit background image Places a graphic in the background Values URI none inherit downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir background repeat Controls how the image is tiled in the background Values repeat tile in all directions repeat x tile horizontally only repeat y only tile vertically no repeat inherit background Dosirlon horizonta Specifies where in the background an image is placed horizontally Percentage and length are with respect
19. The URI of the namespace for the first node innode set Without an argument node set oen h returns the repere ves e per reper nem RR URI for the context node position The number of the context The number of the context node in the context node set In the context node set There are also functions that create node sets pulling together nodes from all over the document For example the function id string returns the set of elements that have an ID attribute equal to the value of string or an empty set if no node matches In a valid document only one node Should be returned because the ID type attribute must have a unique value XPath does not require documents to be valid however so it is possible that more than one element will bereturned downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 6 3 3 Numeric Expressions XPath allows an expression to be evaluated numerically which is useful for comparing positions in a set adding the values of numeric elements incrementing counters and so forth A number in XPath is defined to be a 64 bit floating point number whether it has a decimal point or not Alternatively a number can be specified as NaN not a number in case a conversion fails The rules for converting any expressioninto a numeric value are listed in Table 6 10 Table 6 10 Rules to convert expressions into numbers Expression Rule type Node set The first node is conve
20. You ll get output like this I Evil King Oystro Sends Assassins II Aquaman is Poisoned by Pufferfish III Aqualad Delivers the Antidote IV Atlantis Votes Aquaman into Office The attribute value contains the numeric expression or value to be formatted and the attribute format controls the appearance in this case Roman numerals The default value for ormat is the same as value of plain decimal Table 7 1 shows some ways to use the format attribute Table 7 1 Number formats Format string Numbering scheme 1 11 2 3 4 0 0 1 2 oy 298 01 01 02 03 09 10 11 I HH TET IV l i ii iii iv A A B C D sux la a D C Gy us One stickler is if you wanted an alphabetical list starting with the Roman numeral i You cannot use format i because that indicates lowercase Roman numerals To resolve the ambiguity use an additional attribute Letter value to force the format type to be alphabetical Very large integers often require separator characters to group the digits For example in the United downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir States a comma is used e g 1 000 000 for a million In Germany the comma means decimal point so you need to be able to specify which scheme you want You have two attributes to help you The first grouping separator sets the character used to delimit groups The other grouping size determines how many
21. distinguish XML based languages from each other A document usually attempts to conform to a language of some sort and we need methods to test its level of conformance Schemas the topic of this chapter are the shepherds of markup languages They keep documents from straying outside of the herd and causing trouble For instance an administrator of a web site can use a schema to determine which web pages are legal XHTML and which are only pretending to be A schema can also be used to publish a specification for a language in a succinct and unambiguous way Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 4 1 Basic Concepts In the general sense of the word a schema is a generic representation of a class of things For example a schema for restaurant menus could be the phrase a list of dishes available at a particula eating establishment A schema may resemble the thing it describes the way a smiley face represents an actual human face The information contained in a schema allows you to identify when something is or is not a representative instance of the concept In the XML context a schema is a pass or fail test for documents 4 A document that passes the test is said to conform to it or be valid Testing a document with a schema is called validation A schema ensures that a document fulfills a minimum set of requirements finding flaws that could result in anomalous pr
22. downloaded from fib ommolkcefab ir Team LIB Table of Contents Index Reviews Reader Reviews Errata Learning XML 2nd Edition By Erik T Ray Publisher O Reilly Pub Date September 2003 ISBN 0 596 00420 6 Pages 416 In this new edition of the best selling title the author explains the important and relevant XML technologies and their capabilities clearly and succinctly with plenty of real life projects and useful examples He outlines the elements of markup demystifying concepts such as attributes entities and namespaces and provides enough depth and examples to get started Learning XML is a reliable source for anyone who needs to know XML but doesn t want to waste time wading through hundreds of web sites or 800 pages of bloated text Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LIB pL LR dn gr i BLA Leere Table of Contents Index Reviews Reader Reviews Errata Learning XML 2nd Edition By Erik T Ray Publisher O Reilly Pub Date September 2003 ISBN 0 596 00420 6 Pages 416 Copyright Foreword Preface What s Inside Style Conventions Examples Comments and Questions Acknowledgments Chapter 1 Introduction Section 1 1 What Is XML Section 1 2 Where Did XML Come From Section 1 3 What Can Do with XML Section 1 4 How Do I Get Started Chapter 2 Markup and Core Conce
23. downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Swaps a child node with a new one you supply giving you the old one in return appendChild Adds a new node to the end of this node s list of children hasChildNodes True if there are children of this node otherwise it is false cloneNode Returns a duplicate copy of this node It provides an alternate way to generate nodes All properties will be identical except forparentNode which will be undefined andchildNodes which will be empty Cloned elements will all have the same attributes as the original If the argument deep is set to true then the node and all its descendants will be copied hasAttributes DOM2 only Returns true if this node has defined attributes isSupported DOM 2 only Returns true if this implementation supports a specific feature 10 9 1 5 NodeList This class is a container for an ordered list of nodes It is live meaning that any changes to the nodes it references will appear in the document immediately 10 9 1 5 1 Properties Here are the properties for the NodeList class length Returns an integer indicating the number of nodes in the list 10 9 1 5 2 Methods Here are the properties for the NodeList class item Given an integer value n returns a reference to the nth node in the list starting at zero 10 9 1 6 NamedNodeMap This unordered set of nodes is designed to allow access to nodes by name An al
24. fo static content flow name region first verso before sTo OLOO font family myriad verdana sans serif font weight bold font size l2pt Space after 2mm lt xsl choose gt xsl when test self chapter lt xsl text gt CHAPTER lt xsl text gt xsl call template name chapnum gt lt xsl when gt xsl when test sSelf appendix gt lt xsl text gt APPENDIX lt xsl text gt xsl call template name chapnum gt lt xsl when gt lt xsl choose gt eTrosblogk EOD LOCI border top solid ipt black padding before 2mm font family myriad verdana sans serif tfont weight bold font size 18pt xsl apply templates select title e t Block eclToseratic gcontenr fo static content flow name region first verso after downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir ey LO border top solid lpt black padding before 2mm font family myriad verdana sans serif font weight bold font size 8pt text align 2 left lt fo page number gt lt TO DLock gt fo static content lt START OF CHAPTER ON EVEN PAGE fo static content flow name region first recto before SIO OLOCO font family myriad verdana sans serif font weight bolq font size l2pt text align right Space after 2mm lt xsl choose gt xsl when test self chapter xsl text CHAPTER lt xsl text gt xsl call template name chapnum gt l
25. tip warning gt LTO DOCK margin left 20mm margin right 10mm xsl apply templates erro rblegi downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt xsl template gt 8 6 5 Lists Lists are more complex than your average block They contain a sequence oflist items with an optional label You can think of a really simple list as a bunch of small paragraphs However lists are often more complicated than that In numbered lists the item has a number or letter for a label Bulleted lists use some kind of symbol for a label A label may even be a piece of text such as in a term definition list XSL uses four FOs to put together a list The root of the list islist block a container of list item objects Each 1ist itemhas two children a list item label and list item body Figure 8 9 diagrams this list structure Figure 8 9 The structure of lists list item list irem label list item body provisianal Aahel separatian list item label list tem body provisional distance between starfs list block has two parameters for fudging the geometry of list itemS provisional distance between starts sets the preferred distance between the start of the label and the item body The space between the end of the label and the item body is controlled by the propertyprovisional label separation In list item label you can set the parameter end indent to label end This function
26. which is a component of the document that the parser will inse before parsing For example this entity declaration creates an entity namedcnap2 out of the file chO2 xr CLHENTITY chapa SIXSLbEM oGh02 9ml You can insert this entity in the document using anentity reference which takes the form in Figure 2 8 consists of the entity name 2 bounded on the left by an ampersand 1 and on the right by a semicol 3 You can insert it anywhere in the document element or one of its descendants The parser will repla it with its value taken from the external resource before parsing the document Figure 2 8 Form of an entity reference downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir In this example the entity reference is inserted in the XML inside abook element lt book gt lt title gt My Exciting Book lt title gt amp chap2 ebook Alternatively an entity declaration may specify an explicit value instead of a system or public identifier This takes the form of a quoted string The string can be mixed content any combination of elements ai character data For example this declaration creates an entity called jobtitie and assigns it the text lt jobtitle gt Herder of Cats jobtitle lt ENTITY jobtitle lt jobtitle gt Herder of Cats jobtitle We re really just scratching the surface of entities I ll cover entities in much greater depth later in the chapter Team LiB downloaded
27. A transformation functions similarly to a stylesheet except that instead of simply applying formatting rules to elements it can alter the structure of a document to produce a document with a new structure Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Colophon Our look is the result of reader comments our own experimentation and feedback from distribution channels Distinctive covers complement our distinctive approach to technical topics breathing personality and life into potentially dry subjects The animal on the cover of Learning XML Second Edition is a hatching chick Chickens have been around for at least 3 000 years A hen typically lays one egg at a time and will sit on the egg keeping it warm until it hatches The incubation period for a chicken egg Is approximately 21 days from fertilization to hatching Before hatching the chick absorbs the egg yolk which can sustain it fo the first three days of its life The most popular laying chicken in North America is the leghorn which can produce eggs from five months of age until about a year and a half Philip Dangler was the production editor and proofreader forLearning XML Second Edition Melanie Wang was the copyeditor Mary Brady and Darren Kelly provided quality control James Quill provide production assistance Octal Publishing wrote the index Ellie Volckhausen designed the cover of this book based on a seri
28. Any style settings that you want to redefine or don t need can be overridden in the local stylesheet One reason to combine stylesheets is modularity It may be more manageable to break up a large stylesheet into several smaller files For example we could store all the styles pertaining to math equations in math css and all the styles for regular text intext css The command import links the current stylesheet to another and causes the style settings in the target to be imported Gimport url http www example org mystyles math css import url http www example org mystyles text css Some of the imported style rules may not suit your taste or they may not fit the presentation You can override those rules by redefining them in your own stylesheet Here we ve decided that the rule for ni elements defined in text css needs to be changed import url http www example org mystyles text css hl font size 3em redefinition Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 5 3 Rule Matching We will delve now into thedetails of selector syntax and all the ways a rule can match an element or attribute Don t worry yet about what the properties actually mean I ll cover all that in the next section For now concentrate on how rules drive processing and how they interact with each other Figure 5 7 shows the general syntax for selectors They typically consist
29. In other words there should be a start tag for every end tag An unbalanced piece of XML is really difficult to work with in the XML environment and certainly with XPath Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 6 2 Finding Nodes There are still a few cultures on earth who can name their ancestors back ten generations or further Here is Sam the son of Ben the son of Andrew the son of This chain of generations helps establish the identity of a person showing that he or she is a member of such and such a clan or related to another person through some shared great great uncle XPath too uses chains of steps except that they are steps in an XML tree rather than an actual family tree The terms child and parent are still applicable Alocation path is a chain of location steps that get you from one point in a document to another If the path begins with an absolute position say the root node then we call it anabsolute path Otherwise it is called a relative path because it starts from a place not yet determined A location step has three parts an axis that describes the direction to travel a node test that specifies what kinds of nodes are applicable and a set of optionalpredicates that use Boolean true false tests to winnow down the candidates even further The axis is a keyword that specifies a direction you can travel from any node You can go up thro
30. S T U IV W X absolute location terms absolute measurements absolute paths abstract rules activities activity W3C standards process actuation links addressing standards aggregate definitions alignment Amaya ancestry CSS APIs Application Programming Interfaces SAX 2nd XPath as applications 2nd apply templates element arc areas 2nd ASCII character set associating stylesheets with documents attributes 2nd CSS DTDs elements nodes RELAX NG xml lang XSLT authoring documents auxiliary objects axis Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C ID E F G H 1 J K L EM N O P IQ IR S T U IV W X background properties base URLs Basic Multilingual Plane BMP binding data block elements box model formatting with block progression direction block level flow objects blocks 2nd CSS properties narrative documents objects simple BMP Basic Multilingual Plane BOM byte order mark Boolean expressions 2nd borders 2nd properties boundaries 2nd bounding box box model 2nd briefing packages byte order mark BOM Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LIB A B C D E F G H 1 J K L EM N O P IQ R S T U IV W X call template directive candidate recommendation W3
31. SAX 2nd Java simple blocks simple data storage databases dictionaries records simple mail transfer protocol SMTP simple type sizing fonts 2nd SMIL Synchronized Multimedia Integration Language SMTP simple mail transfer protocol sorting elements source trees SOX Schema for Object Oriented XML Spacing properties specifications character encodings CSS human languages stacking areas Standards addressing descriptive procedural hypertext linking markup multimedia organizations programming publishing querying science style transformation standards bodies 2nd ISO state information storage data simple data downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir databases dictionaries records streams processing PYX strings expressions 2nd ranges structure markup styles See also formatting fonts standards stylesheets See also CSS 2nd combining 2nd C55 applyin associating limitations of need for languages transformation default rules elements executing formatting history of matching nodes modularity naming overview of precedence redirecting templates sub sequence specifiers subtrees SVG Scalable Vector Graphics language Synchronized Multimedia Integration Language SMIL syntax CDATA section core CSS matching rules elements location path shortcuts namespaces processing instructions well formedness XPointer system identifiers 2nd
32. Software developed for this purpose converts MoDL documents into a temporal spatial format called Virtual Reality Markup Language VRML When viewed in a VRML reader molecules dance around and bump into each other Read more about MoDL athttp violet csa iisc ernet in modl and VRML at http www web3d org downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Again there are limitations Movies just like graphics can be vector based or rasterized Formats like MPEG and MOV are compressed sequences of bitmaps a huge amount of pixel information that XML would not be good at organizing Simple shapes bouncing around in space are one thing but complex scenes involving faces and puppy dogs are probably never going toinvolve XML 3 3 2 Presentation Versus Conceptual Encoding Moving up in complexity is mathematics The Mathematics Markup Language MathML attacks this difficult area with two different modes of markup presentational and conceptual If we were describing an equation we could do it in two ways could say the product of A and B or could write on a chalkboard the more compact A x B both conveying the same idea MathML allows you to use either style and mix them together in a document Consider the mathematical expression in Figure 3 3 This example was generated with MathML and displayed with Mozilla which recognizes MathML as of version 1 1 Figure 3 3 A complex fraction Example 3 9 is
33. blocks of all XML derived languages elements attributes entities processing instructions and more And I ll show you how they all fit together to make a well formed XML document Mastering these concepts is essential to understanding every other topic in the book so read this chapter carefully All of the markup rules for XML are laid out in the W3C s technical recommendation for XML version 1 0 http www w3 org TR 2000 REC xml 20001006 This is the second edition of the original which first appeared in 1998 You may also find Tim Bray s annotated interactive version useful Go and check it out at http www xml com axml testaxml htm Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 2 1 Tags If XML markup is a structural skeleton for a document then tags are the bones They mark the boundaries of elements allow insertion of comments and special instructions and declare settings fo the parsing environment A parser the front line of any program that processes XML relies on tags to help it break down documents into discrete XML objects There are a handful of different XML object types listed in Table 2 1 Table 2 1 Types of tags in XML Object Purpose Example Represent information at a specific point in the empty element xref linkend abc gt document psi Group together elements and character data lt p gt This is a paragraph p declaration Ada de
34. business or sales promotional use Online editions are also available for most titles nttp safari oreilly com For more information contact our corporate institutional sales department 800 998 9938 orcorporate Qoreilly com Nutshell Handbook the Nutshell Handbook logo and the O Reilly logo are registered trademarks of O Reilly amp Associates Inc Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks Where those designations appear in this book and O Reilly amp Associates Inc was aware of a trademark claim the designations have been printed in caps or initial caps The association between the image of a hatching chick and the topic of XML is a trademark of O Reilly amp Associates Inc While every precaution has been taken in the preparation of this book the publisher and authors assume no responsibility for errors or omissions or for damages resulting from the use of the information contained herein Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Foreword In 1976 two landers named Viking set down on Mars and turned their dish shaped antennae toward earth A few hours later delighted scientists and engineers received the first pictures from the surface of another planet Over the next few years the Viking mission continued to collect thousands of images instrument readings and engineering data e
35. causing the output to be single spaced lt para gt lt listitem gt varlistentry varlistentry term option t option term lt listitem gt lt para gt Implies the option v option option and displays tab characters as keysym I keysym as well lt para gt lt listitem gt varlistentry lt varlistentry gt lt term gt lt option gt u lt option gt lt term gt lt listitem gt lt para gt The lt option gt u lt option gt option guarantees that the output is unbuffered lt para gt lt listitem gt lt varlistentry gt lt varlistentry gt lt term gt lt option gt v lt option gt lt term gt lt listitem gt lt para gt Displays non printing characters so they are visible Control characters print as keysym X keysym for control X the delete character octal 0177 prints as keysym keysym Non ascii characters with the high bit set are printed as lt literal gt M lt literal gt for meta followed by the character for the low 7 bits lt para gt lt listitem gt lt varlistentry gt lt variablelist gt lt para gt The lt command gt cat lt command gt utility exits 0 on success and amp gt 0 if an error OCCuUrs lt para gt refsectl refsectl title Bugs title lt para gt Because of the shell language mechanism used to perform output redirection the command command cat filel file2 amp gt filel lt command gt will cause the original data in filel to be de
36. comprising a human readable record such as a book article or essay But in XML a document is even more general it s the basic unit of XML information composed of elements and other markup in an orderly package It can contain text such as a story or article but it doesn t have to Instead it might consist of a database of numbers or some abstract structure representing a molecule or equation In fact one ol the most promising applications of XML is as a format for application to application data exchange Keep in mind that an XML document can have a much wider definition than what you might think of as a traditional document The following are short examples of documents The Mathematics Markup Language MathML encodes equations A well known equation among physicists is Newton s Law of Gravitation F GMm r2 The document inExample 1 2 represents that equation Example 1 2 A MathML document lt xml version 1 0 gt math xmins http www w3 org 1998 Math MathML mir lt mi gt lt mo gt lt mo gt lt mi gt G lt mi gt mooeInvisirbleTimess mos lt M rac mrow downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt mi gt M lt mi gt more invisi blelines lt 7ime gt lt miom lt mi lt mrow gt SApply lt power gt CIT Q1 lt n eon apply mfrac lt math gt While one application might use this input to display the equation another might use it
37. eval SdocRef S parser parse file S fileName Jj die Parser error 0 3 if 8 jJ map proc to elems amp fix_iterms S docRef downloaded from lib ommolketab ir downloaded from lib ommolketab ir open OUT gt SfileName or die Can t write fileName princ OUT SdgdocRef SLtoSstreingQ0s close OUT sub map proc to elems my Sproc SnodeRef Q my SnodeType SnodeRef gt nodeType if SnodeType SnodeTypes document map proc to elems proc SnodeRef gt getDocumentElement elsif nodeType SnodeTypes element amp Sproc SnodeRef foreach my childNodeRef nodeRef getChildnodes map proc to elems proc S childNodeRef sub fix iterms my SnodeRef shift return unless nodeRef nodeName eq indexterm my SparentNodeRef nodeRef parentNode return unless parentNodeRef nodeName eq title SparentNodeRef gt removeChild SnodeRef my SancestorNodeRef SparentNodeRef parentNode SancestorNodeRef gt insertAfter SnodeRef SparentNodeRef j Now let s make sure this thing works Here is a sample data file before processing chapter lt title gt lt indexterm gt lt primary gt wee creatures lt primary gt lt indexterm gt Habits of the Wood Sprite lt indexterm gt lt primary gt woodland faeries lt primary gt lt indexterm gt lt title gt lt indexterm gt lt primary gt sprites lt primary gt lt secondary gt woodland l
38. fib ommolkcefab ir display type block border thin solid black padding 5em margin 5em j name phone email address display type block margin top 2em margin bottom 2em This stylesheet has three rules The first matches anyaddressbook element The name to the left of the open bracket is a selector which tells the processor what element this rule matches The items inside the brackets are the property declaration a list of properties to apply The syntax for a CSS rule is shown in Figure 5 6 It consists of a selector 1 for matching elements and a declaration 2 for describing styles The declaration is a list of name value assignments 3 in which each style property 4 is assigned to a value 5 with a colon separator Figure 5 6 CSS rule syntax selector propertyl valuel propertyi value CSS also has a syntax for comments Anything inside a comment is ignored by the processor The start delimiter is and the end delimiter is A comment can span multiple lines and may be used to enclose CSS rules to remove them from consideration this part will be ignored gurble color red burgle color blue font size 12pt af Whitespace is generally ignored and provides a nice way to make stylesheets more readable The exception is when spaces act as delimiters in lists Some properties take multiple arguments separated with spaces like border below sidebar borders thin
39. informatian in a farm tailored to your needs As an open standard xm is not tied to the fortunes of any single company nor married to any particular software With Unicode as its standard character set xwr supports a staggering number of writing systems scripts and symbols from Scandinavian runic characters to Chinese Han ideographs XML Offers many ways to check the quality of a document with rules for syntax Internal link checking comparison te document models and data typing With its clear simple syntax and unambiguous structure XML is casy to read and parse by humans and programs alike XML ls easily combined with stylesheets to create formatted J d m needed READ OFF These are just a few of the many XML editors available Table 1 1lists a few more along with their featv Table 1 1 Comparison of XML editor features editor Adobe FrameMaker 7 0 Arbortext Adept Corel XMetal yes downloaded from lib ommolketab ir structure validity idi element macros unicode outline highlighting checking checking menus support view TEE formatted display a e downloaded from fib ommolkcefab ir tag structure validity element unicode outline formatted editor e l macros highlighting checking checking menus support view display emacs psgml yes yes yes yes yes no no no MOPANI es es es es es no es es XMLEditor y
40. initial surge of webification Although HTML had only limited presentational capabilities built in it was enough to satisfy the hordes of new web authors Easy to implement and even easier to learn HTML was soon stretched far beyond its original intentions as a simple report formatting language forced to encode everything from product catalogs to corporate portals But the very thing that led to its rapid uptake presentational markup is also holding HTML back Here are some problems associated with presentational markup and some solutions provided by stylesheets Low information content Presentational markup is not much better than plain text A machine can t understand the difference between a typical body paragraph and a poem or code sample Nor does it know that one thing is marked bold because it s a stock price and another is bold because it s the name of a town Consequently you can t easily mine pages for information Search engines can only try to match character strings since any sense of context is missing from the markup With stylesheets you are free to mark up a document in a way that preserves information XML markup languages are tailored for their data using element names that describe what things are rather than how they should look This makes it possible to create data mining software or search engines that use markup information in addition to content Management nightmare When your markup is presentational the des
41. lt ELEMENT description PCDATA gt lt ELEMENT time start PCDATA gt lt ELEMENT time end PCDATA gt lt ATTLIST day date CDATA REQUIRED gt Although the DTD is more compact it relies on a special syntax that is decidedly not XML ish RELAX NG accomplishes the same thing with more readability RELAX NG also offers a compact syntax that looks somewhat like a DTD but offers all the features of RELAX NG For a brief introduction see http www xml com pub a 2002 06 19 rng compact html James Clark s Trang program available at http www thaiopensource com relaxng trang html makes it easy to convert between RELAX NG RELAX NG Compact Syntax and DTDs as well as create W3C XML Schema from any of these formats The basic component of a RELAX NG schema is apattern A pattern denotes any construct that describes the order and types of structure and content It can be an element declaration an attribute declaration character data or any combination Elements in the schema are used to group order and parameterize these patterns Note that any element or attribute in a namespace other than the RELAX NG namespace http relaxng org ns structure 1 0 is simply ignored by the parser That gives us a mechanism for putting in comments or annotations which explains why created theann namespace in the previous example 4 4 1 Elements The element construct is used both to declare an element and to establish where the ele
42. lt indexterm gt lt section gt lt chapter gt The indexterms have been moved out of the titles as we expected Other indexterms have not been affected The other contents in titles are still there unchanged including some extra space that abutted the indexterm elements In short it worked Perl works well for most of my XML needs Historically it has had a few issues with character encodings but these problems are gradually going away as Perl adopts multibyte characters and adds support for Unicode Check out http www cpan org for a huge list of modules that do everything with XML including XSLT XPath DOM SAX and more You will also want to check out Python which many people tout as superior in its object oriented support It is quickly growing in popularity though it will be a while before it can match Perl s wealth of libraries Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 10 Other Options As XML has spread more and more people have had creative and often useful ideas about how to process it 10 10 1 XPath as API The XPath language provides a convenient method to specify which nodes to return in a tree context A parser written as a hybrid will only need to return a list of nodes that match an XPath expression stream parser efficiently searches through the document to find the nodes then passes the locations to a tree builder that assembl
43. most important however is the font family e g Courier Helvetica and Times Each family comes in different styles and weights such as italic bold and heavy The font family property is declared with a comma separated list of font preferences starting with the most specific and desirable and finishing with the most generic This list provides a series of alternatives in case the user agent doesn t have access to the specific font you request At the very end of the list should be a generic font class essentially allowing the user s software to decide which font matches best Some generic font classes are serif Fonts that have decorative appendages or serifs fit in this category Some common serif fonts include Palatino Times and Garamond sans serif These fonts lacking serifs are relatively plain in comparison to the serif fonts Helvetica and Avant Garde are in this group monospace downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir In these fonts each character occupies the same amount of space unlike most fonts where letters are packed together in varying widths This font type is typically used to render computer programs teletype simulations and ASCII artl2 Examples of monospace fonts are Courier and Monaco 1 See http www textfiles com art cursive Fonts that connect characters in a simulation of calligraphy or handwriting fall in this group Such typefaces are often u
44. otherwise Let s apply this rule to the following input tree lt warning xml lang de gt lt para gt Bitte kein rauchen lt para gt lt warning gt The para Inherits its language property from the warning that contains it and the first choice in the template rule will be used Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 10 Programming XML was designed to bridgethe gap between humans and computers making data easily grappled by both If you aren t able to find an existing application to take care of your XML needs you may find writing your own a good option XML has great possibilities for programmers It is well suited to being read written and altered by software Its syntax is straightforward and easy to parse It has rules for being well formed that reduce the amount of software error checking and exception handling required It s well documented and there are many tools and code libraries available for developers in just about every programminc language And as an open standard accepted by financial institutions and open source hackers alike with support from virtually every popular programming language XML stands a good chance of becoming the lingua franca for computer communications We begin the chapter by examining the issues around working with XML from a developer s point of view From there we move to common coding strategies and best prac
45. planes BMP points 2nd returning positioning elements positions Post Schema Validation Infoset PSVI precedence rules preceding siblings predefined character entities predicates XPath prefixes namespaces 2nd presentation 2nd downloaded from fib ommolkcetftab ir downloaded from lib eommolketab ir preserve space element printing XSL FO procedural standards processing client side redirecting XSLT rules server side streams trees XSL FO processing instructions 2nd 3rd 4th nodes XSLT Processingl nstruction class processors CSS processors XML programming 2nd See also markup 3rd APIs DOM events J DOM limitations of objects parsing Perl pull parsing PYX SAX Java standards streams trees XSLT prologs 2nd documents schemas properties backgrounds borders compound conflicts CS5 blocks display types generated text inheritance text units of measurement declarations stylesheet rules downloaded from lib ommolketab ir downloaded from lib eommolketab ir dictionaries elements fonts inheritance Spacing stylesheets proposed recommendation W3C standards process 2nd pseudo classes pseudo element selectors PSVI Post Schema Validation Infoset PUBLIC identifier public identifiers 2nd publishing standards pull parsing push model PYX Team LiB downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir Team LIB A B
46. scripting languages and stylesheets as well as better printing facilities an documents that are more accessible to users with disabilities HTML 4 also takes great strides towards the internationalization of documents Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 8 Descriptive Procedural SOAP SOAP is a protocol for exchanging information W3C Status The SOAP 1 2 specification formerly the Simple Object Access Protocol became a W3C Recommendation in June 2003 SOAP 1 2 Part 0 Primer is published at http www w3 org TR soap12 partO SOAP 1 2 Part 1 Messaging Framework is published at http www w3 org TR soap12 part1 and SOAP 1 2 Part 2 Adjuncts is published at http www w3 org TR soap12 part2 SOAP Version 1 2 Specification Assertions and Test Collection also a Recommendation is published athttp www w3 org TR soap12 testcollection Description SOAP is an XML based protocol for exchanging information in a decentralized distributed environment It consists of three parts an envelope that defines a framework for describing what is in a message and how to process it a set of encoding rules for expressing instances of application defined data types and a convention for representing remote procedure calls and responses RDF The Resource Description Framework provides a standard way of representing metadata W3C Status The RDF Model a
47. so I m not allowed to use it in a telegram No problem it s easy to add new elements This shows how you can detect problems with structure and grammar in a document The most important benefit to using a DTD is that it allows you to enforce and formalize a markup language You can make your DTD public by posting it on the web which is what organizations like the W3C do For instance you can look at the DTD for strict XHTML version 1 0 at http www w3 org TR xhtml1 DTD xhtml1 strict dtd It s a compact and portable specification though a little dense to read One limitation of DTDs is that they don t do much checking of text content You can declare an element to contain text called PCDATA in XML or not and that s as far as you can go You could not check whether an element that should be filled out is empty or if it follows the wrong pattern Say for example wanted to make sure that theco element in the telegram isn t empty so have at least someone to give it to With a DTD there is no way to test that An alternative document modeling scheme provides the solution XML Schemas provide much more detailed control over a document including the ability to compare text with a pattern you define Example 1 8 shows a schema that will test a telegram for completely filled out elements Example 1 8 A schema for telegrams xs schema xmlns xs http www w3 org 2001 XMLSchema xs element name telegram type telegramtype
48. string expressions XSLT hone nonelement content descriptors notations PYX number expressions 2nd numbered character references numeric references numeric text formatting numeric values counters Team LIB downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E IF G IH 1 J K L EM N O P IQ R S T U IV W X objectification objects elements complex data formatting inheritance among linked page sequence master programming XSL FO areas DocBook formatters formatting overview of page layout printing processing TEI XML odd numbered recto pages online resources open standards 2nd Opera operators comparison numeric output element outputting node values overlapping overriding imported definitions Team LiB downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E F EG H 1 DJ K L M EN O P Q R S ET U V W X padding 2nd rectangles page layout page masters DocBook page sequence masters page sequence master objects parameters datatypes entities XSLT templates parsed character data parsers parsing selecting parsers unparsed entities paths expressions Boolean node set number strings shortcuts patterns named XSLT PCDATA parsed character data Perl programming physical structures 2nd
49. template below will change anxref element into text that includes this type of citation lt xsl template match 2 xref role Gpage number downloaded from lib ommolketab ir downloaded from lib ommolketab ir 1 The attribute linkend holds the ID of the element being cited lt xsl variable name idref gt lt xsl value of select linkend gt lt xsl variable gt lt Go to the element being cited and output some text depending on its type gt lt xsl for each select id Sidref gt lt xsl choose gt xsl when test self sectl gt the section lt xsl when gt xsl when test self table the table lt xsl when gt xsl when test 2 self fig the figure lt xsl when gt xsl otherwise the thing lt xsl otherwise gt lt xsl choose gt xsl for each lt i Finally output the page number gt lt xsl text gt on page lt xsl text gt lt fo page number citation gt xsl attribute name ref id gt lt xsl value of select linkend gt xsl attribute fo page number citation lt xsl template gt Team LiB downloaded from lib ommolketab ir gt downloaded from fib ommolkcefab ir Team LiB 8 5 An Example TEI Let us take a break now from terminology and see an actual example The document to format is a Shakespearean sonnet encoded in TEI XML a markup language for scholarly documents shown in Example 8 2 t consists of a he
50. this markup language could be edited formatted and searched by different programs because of its content based tags IBM a huge publisher of technical manuals has made extensive use of GML proving the viability of generic coding 1 Cute fact the acronym GML also happens to be the initials of the three inventors Inspired by the success of GML the American National Standards Institute ANSI Committee on Information Processing assembled a team with Goldfarb as project leader to develop a standard text description language based upon GML The GCA GenCode committee contributed their expertise as well Throughout the late 1970s and early 1980s the team published working drafts and eventually created a candidate for an industry standard GCA 101 1983 called the Standard Generalized Markup Language SGML This was quickly adopted by both the U S Department of Defense and the U S Internal Revenue Service In the years that followed SGML really began to take off The International SGML Users Group started meeting in the United Kingdom in 1985 Together with the GCA they spread the gospel of SGML around Europe and North America Extending SGML into broader realms the Electronic Manuscript Project of the Association of American Publishers AAP fostered the use of SGML to encode general purpose documents such as books and journals The U S Department of Defense developed applications for SGML in its Computer Aided Acquisition and Logistic
51. to channels that mix together lots of different sources you can subscribe to individual sites for an even higher level of customization Everything from the BBC to a swarm of one person weblogs are at your disposal Publishing has never been easier RSS works like the cover of a magazine beckoning to you from the newsstand Splashed all over the cover graphic are the titles of articles like Lose Weight with the Ice Cream Diet and Ten Things th Government Doesn t Want You to Know About UFOs At a glance you can decide whether you must have this issue or National Geographic instead It saves you time and keeps the newsstand owner from yelling at you for reading without buying There are a few different models of publishing with RSS Thepull model is where a content aggregator checks an RSS file periodically to see if anything has been updated pulling in new article as they appear In the push model also called publish and subscribe the information source informs the content aggregator when it has something new to offer In both cases RSS serves as a menu for the aggregator or the user logged into it to decide whether the articles are of interest Example 3 11 shows a sample of RSS describing a fictional web site The owner of a web site will register this file with all the aggregators it wants to be listed under and hope that people will be convinced by the descriptions that it s interesting enough to subscribe to downloaded from lib
52. 1990s everyone wanted their own web site remember learning HTML from friends and the excitement felt when saw my virtual homestead suddenly become accessible to thousands of computer users Back then had only a very limited understanding of things like good design standards and best practices They seemed like lofty concepts with little relation to me and my happy experiments So like everyone else cut corners sacrificed good taste and ignored rules because all that mattered was seeing something display reasonably well in a browser Since then the novelty has worn off and my situation is vastly different My concern has shifted from How can get something to display at all to How can make my information available to everyone who tries to look at it regardless of what software they are using on what platform and ir which media format And instead of asking How can create an HTML page now ask How can make this vast amount of information easier to update store and publish And where before might wonder how to achieve some effect in HTML like making some lines of text larger than other lines now have to cope with a variety of different XML formats and extremely detailed design needs Cascading Style Sheets CSS are the first piece of this puzzle They have been around for a long time but for several reasons they were slow to take off Now sites likewired com are totally based on CSS and they actuall
53. 3 2 and referenced in the message element A fourth entity amp 4241 is a numbered character entity that represents the character n This entity is referenced but not declared no declaration is necessary because numbered character entities are implicitly defined in XML as references to characters in the current character set For more information about character sets see Chapter 9 The XML parser simply replaces the entity with the correct character The previous example looks like this with all the entities resolved lt xml version 1 0 gt lt DOCTYPE message SYSTEM xmlstuff dtds message dtd gt lt message gt lt opening gt Dear Mr Rufus Xavier Sasperilla lt opening gt lt body gt We have an exciting opportunity for you A set of ocean front cliff dwellings in Pinata Mexico have been renovated as time share vacation homes They re going fast To reserve a place for your holiday call Ms Sally Tashuns at lt number gt 617 555 1299 lt number gt Hurry Mr Rufus Xavier Sasperilla Time is running out lt body gt lt message gt All entities besides predefined ones which I ll describe in a moment must be declared before they are used in a document Two acceptable places to declare them are in the internal subset which is ideal for local entities and in an external DTD which is more suitable for entities shared between documents If the parser runs across an entity reference that hasn t been declared either i
54. 3rd Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E F EG H 1 DJ K L M EN O P Q IR S ET U V W X tables XSL FO tags 2nd 3rd TEI Text Encoding Initiative 2nd See also TEI XML TEI XML templates documents XSLT 2nd default rules matching nodes precedence redirecting terminal nodes testing nodes text See also CSS colors comments 2nd XSLT CSS generating properties markup narrative documents blocks complex structures DocBook flow linked objects metadata XHTML nodes 2nd numeric regions text editors Text Encoding Initiative TEI 2nd See also TEI XML titles tokens tools markup language toolkit XML top level element flows tracking versions traits 2nd transformation 2nd 3rd 4th 5th See also XSLT 6th elements executing formatting history of downloaded from lib eommolketab ir downloaded from fib ommolkcetftab ir modularity objects overview of standards templates default rules matching nodes naming precedence redirecting transparent backgrounds Tree Regular Expressions for XML TREX tree representation of nodes XML documents trees 2nd area nodes searching subtrees types of processing programming refined formatting object result source XPath Boolean expressions expressions node set expressions number expressions st
55. Associating a stylesheet to a document There is no hard and fast rule for associating resources to documents in XML Each markup language may or may not provide support for stylesheets Some languages like MoDL have their own software to display or process the data so it wouldn t make any sense to use stylesheets n others the language doesn t have an explicit method for association so stylesheets are a good idea as is the case with DocBook HTML happens to define an element for linking resources like stylesheets to the document Therink element will bind a web page to a CSS stylesheet like this html head lt title gt The Behavior of Martian Bees lt title gt link rel stylesheet type text css href honey css lt head gt Alternatively in HTML you can embed the stylesheet inside the document ee A lt head gt lt title gt The Behavior of Martian Bees lt title gt lt style gt body background color wheat Color brown font family sans serif sect border thin solid red padding 0 5em style lt head gt Of course this is more limiting since the stylesheet can t be applied to more than one document ano the document is stuck with this stylesheet In general think keeping the two separate is a better idea but there may be advantages to putting them together such as making it easier to transport a document through email These two solutions work because HTML evolved together with s
56. Brand 14 nor important gt lt item gt toothpaste lt item gt lt item gt rocket engine lt item gt lt item optional yes gt caviar lt item gt CI ShoopilngllsBLt As PYX it would look like this ShopDpnDnglrst n item toothpaste item n item rocket engine item downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir n item Aoptional yes Cayiar item n shoppainglist Notice that the comment didn t come through in the PYX translation PYX is a little simplistic in some ways omitting some details in the markup It will not alert you to CDATA markup sections although it will let the content pass through Perhaps the most serious loss is character entity references which disappear from the stream You should make sure you don t need that information before working with PYX PYX is an interesting alternative to SAX and DOM for quick and dirty XML processing It s useful for simple tasks like element counting separating content from markup and reporting simple events However it does lack sophistication making it less attractive for complex processing Today consider it to be more of interest for historical reasons than as arecommendation Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 8 SAX The Simple API for XML SAX is one of the first and currently the most popular method for working with XML da
57. But think about this a namespace is actually a region of the document not just the possession of a single element All the descendants of that element will be affected XML processors must pay special attention to namespaces so XPath makes it a unique node type What isn t included in this list is the DTD You can t use XPath to poke around in the internal or external subsets XPath just considers that information to be implicit and not worth accessing directly It also assumes that any entity references are resolved before XPath enters the tree This is probably a good thing because entities can contain element trees that you would probably want to be able to reach It isn t strictly true that XPath will maintain all the information about a document so that you could later reconstruct it letter for letter The structure and content are preserved however which makes it semantically equivalent What this means is if you were to slurp up the document into a program and then rebuild it from the structure in memory it would probably not pass adiff LH test Little things would be changed such as the order of attributes attribute order is not significant in XML Whitespace between elements may be missing or changed and entities will all be resolved To compare two semantically equivalent documents you d need a special kind of tool One that know o in the Perl realm is the module XML SemanticDiff which will tell you if structure or content is the
58. LiB Chapter 8 Presentation Part Il XSL FO XSL FO rounds out thetrio of standards that make up XSL The FO stands for Formatting Objects which are containers of content that preserve structure and associate presentational information XSLT prepares a document for formatting using XPath to disassemble it and produce an XSL FO temporary file to drive a formatter Under a W3C charter the XSL Working Group started to design a high powered formatting language in 1998 XML was still new but XSL was understood early on to be a factor in making it useful The group split its efforts on two related technologies a language for transformations XSLT and anothe for formatting XSL FO XSLT the first to become a recommendation in 1999 demonstrated itself tc be generally useful even outside of publishing applications XSL followed as a recommendation in 2001 Cascading Style Sheets a jewel in the crown of the W3C had been around for a few years and was e strong influence on the development of XSL Its simple but numerous property statements make it easy to learn You will see that quite a few of these properties have been imported into XSL FO The CSS box model elegant and powerful is the basis for XSL FO s area model Mostly what has been added to XSL FO are semantics for handling page layout and complex writing systems The principal advantages of XSL over CSS are e Print specific semantics such as page breaking CSS happens to be moving i
59. May lt FOsblock gt lt fo block space after 4mm start indent 5mm And summer s lease hath all too short a date to lock lt Rest removed because it s more of the same gt lt TO LLoOWw gt lt fo page sequence gt lt J Io 7 oor formatted this with FOP and got a PDF file as output Figure 8 8 shows how it looks in Acrobat Reader Figure 8 8 The sonnet in PDF downloaded from lib ommolketab ir downloaded from lib ommolketab ir Team LIB downloaded from lib ommolketab ir Shakespeare s Sonnets A VIII Shall I Compare Thee to a Summer s Dar hy William Shakespeare Shall compare thee to a summers day Thou art more lovely and more temperate Rough winds do shake the darling buds of May And summer s lease hath all too short a date Sometime Leo hot the eye of heaven shines And often is his cold complexion dimm d And every fair from tair sometime declines By chance or nature s changing course untrimm d Hut thy etemal summer shall not fade Nor lose possession of that fair thou owest Nor shall Death brag thou wanders in his shade When in etemal lines to time thou grewest SO ong as men can breathe or eyes can see So long lives this and this gives life to thee downloaded from fib ommolkcefab ir Team LiB 8 6 A Bigger Example DocBook The last example was relatively simple lacking complex structures like lists tables and footnotes It also was quite sho
60. Morphon manual available in POF format as T G section HTMLHelp in Windows amd ot powi morplon con as i title hiin s also an example of what a DaocBaaok document Y para can loak like ii 3 ulink 4 i j H Sel Mame value Type Default value v url http www m CDATA REC O type CDATA 0 E id ID Auta commit Apply LEVEL Jarticle section 4 para ulink Figure 1 7 Epic Editor from Arbortext downloaded from lib ommolketab ir Hie E ris View Insert RN o Format Window v Cu 4 e er uu HEE S BUE Rewe B a Te D c B 3 Y i c Los e chapter LE Wie 1 Introduct HEJ para The Extensib Lg acronym XMI m j is a date storage toolki A short list o a sfera says it all para itemizedlist B E listitem 1 m a T A acronym cam store and or para fisttenn E Nstftem TE para ns an Je acronym i 15 not ned to the j distitem E listitem T mw Lj acronym prices E Bad Me Ae 1 Introduction The Extensible Markup Language zr is a data storage toolkit a configurable vehicle for any kind of information an evolving and open standard embraced by everyone from bankers to web masters In just afew years it s captured the imagination of technology pundits and industry mavens What s the secret of it s success A short list of xmL s features says it all XML Can store and organize just about any kind of
61. On Unix based systems the RCS and CVS packages have both been the trusted friends of developers for years Parameter entities Parameter entities can hold recurring parts of declarations and allow you to edit them in one place In the external subset they can be used in element type declarations to hold element groups and content models or in attribute list declarations to hold attribute definitions The internal subset is a little stricter parameter entities can hold only complete declarations not fragments For example assume you want every element to have an optionalrp attribute for linking and an optional class attribute to assign specific role information Parameter entities which apply only in DTDs look much like ordinary general entities but have an extra in the declaration You can declare a parameter entity to hold common attributes like this SIENIIIY X Gomnmon stuts a ID IMPLIED class CDATA IMPLIED gt That entity can then be used in attribute list declarations amp TIAIThIST foo common atts lt ATTLIST bar common atts extra CDATA FIXED blah gt Note that parameter entity references start with rather than amp 4 2 4 2 Attributes versus elements Making a DTD from scratch is not easy You have to break your information down into its conceptual atoms and package it as a hierarchical structure but it s not always clear how to divide the information The book model is easy because it break
62. SDAaPLS cILISL part label A count 1 gt fuselage left half lt part gt part label B count 1 gt fuselage right half lt part gt part label F count 4 gt steering fin lt part gt part label N count 3 gt rocket nozzle lt part gt part label C count 1 gt crew capsule lt part gt parts list CLHDnStrucLLOons SSLOD Glue parts A and B together to form the fuselage lt step gt lt SLEep gt Apply glue to the steering fins part F and insert them into slots in the fuselage lt step gt SOLD Affix the rocket nozzles part N to the fuselage bottom with a small amount of glue lt step gt SSLeDpe downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Connect the crew capsule to the top of the fuselage Do not use any glue as it is spring loaded to detach from the fuselage lt step gt instructions lt manual gt The whole document is a tree with manual as the root element or document element the parts list and instructions elements are also in the form of trees with roots and branches of their own XML processing techniques often rely on nested trees Trees facilitate recursive programming which is easier and more clear than iterative means XSLT for example is elegant because a rule treats every element as a tree It s important to remember that you cannot take just any fragment of an XML document and expect it to form a node tree It has to be balanced
63. Solid black j 5 2 3 Matching Properties to Elements downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Let s look more closely at this rule addressbook display type block font family sans serif lLont seriset IZDL background color white color blue Qualitatively this rule is like saying for everyaddressbook element display it like a block set the font family to any sans serif typeface with size 12 points set the background color to white and mak the foreground text blue Whenever the CSS processor encounters anaddressbook element it will set apply these properties to the current formatting context To understand how it works think of painting by numbers In front of you is a canvas with outlines c shapes and numbers inside the shapes Each number corresponds to a paint color You go to each shape find the paint that corresponds to the number inside it and fill it in with that color In an hour or so you ll have a lovely stylized pastoral scene with a barn and wildflowers In this analogy the rule is a paint can with a numbered label The color is the property and the number is the selector The selector can be more complex than just one element name It can be a comma separated list of elements It could be qualified with an attribute as in this example which matches a oo element WIth olasse flubber foo flubber color green This dot qualified selector matches an el
64. The new media types are best xml This is your basic XML document with no special processing requested The recipient is expected to know what to do with the data Some developers would like to seetext xm1 deprecated in favor of application xml as XML doesn t precisely fit IETF expectations for the text top level type application xml This is an XML document that requires some preparation before it is useful for viewing Some indication of what application to use will be included The recipient might look inside the document for a DOCTYPE declaration for example text xml external parsed entity application xml external parsed entity Like the above but not necessarily a complete document The recipient will have to assemble the entities into a complete package before parsing the document Liketext xml some developers want text xml external parse entity deprecated application xml dtd The item is a document type definition DTD and not an actual XML document In some cases downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir it may be useful to supply a DTD in addition to the document to help out the XML processor Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 9 3 Specifying Human Languages Specifying a character encoding is crucial for correctly processing and displaying an XML document in a multilingual world But there is a
65. The first shown below numbers each payment and summarizes it nicely in a sentence lt xsl template match payment gt lt a gt lt xsl value of select position gt xeletext gt On lt xslitext gt lt xsl value of select date gt lt xsl text gt you paid lt xsl text gt lt ET lt DD gt lt xsl text gt lt xsl text gt lt xsl value of select amount gt lt b gt lt tt gt lt xsl text gt to lt xsl text gt lt i gt lt xsl value of select payee gt lt i gt lt xsl text gt for lt xsl text gt lt xsl value of select description gt exslrrtexto xsl text gt lt p gt lt xsl template gt This works well enough for most payment types but doesn t quite work whentype atm Notice in the document instance that the atm payment lacks any description of the payee since we assume that the checkbook s author is receiving the funds Let s make a special rule just for this case lt xsl template match payment type atm gt lt p gt lt xsl value of select position gt lt xsl text gt On xslit ext downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt xsl value of s lect date gt lt xsl text gt you withdrew lt xsl text gt CIT s lt xsl text gt s lt xsl text gt lt xsl value of select amount gt ue dor Se AP xsl text from an ATM for xsl text lt xsl value of select description gt lt xsl text gt lt xsl
66. We talked before about how multiple rules can match the same element When that happens all unique property declarations are applied Conflicting properties have to be resolved with a special algorithm to find the best match Consider this stylesheet tfont rtamily ITC Garamond hl font size 24pt n2 4 font size lpt j hl h2 color blue The ni element matches three of these rules The net effect is to render it with the font ITC Garamond at 24 point size in the color blue What if there s a conflict between two or more values for the same property For example there might be another rule in this stylesheet that says downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Had q pebeBx149 34 color red j An n1 that is the first child of its parent would have conflicting values for thecolor property CSS defines an algorithm for resolving conflicts like these The basic principle is that more specific selectors override more general selectors The following list outlines the decision process 1 IDs are more specific than anything else If one rule has an ID selector and another doesn t the one with the ID selector wins More IDs are stronger than fewer though given that IDs are unique within a document a rule doesn t really need more than one 2 More attribute selectors and pseudo classes are stronger than fewer This means that para first child Is more specific than title para
67. Web pages with messages like best when viewed by browser X have fallen into this trap Stylesheets are regulated by standards bodies Instead of inventingad hoc extensions that fragment the community vendors instead are encouraged to implement the same standards a everyone else If something that people need is missing it s better to tell the standard maintaining body than to go it alone That s the theory anyway In practice it doesn t always work CSS has been around for a long time and to date no one has completely implemented it correctly There are also a few vendor extensions Device dependence Designers often focus too much on getting something to lookjust right instead of making it good enough for a range of uses In the process they end up making their document too inflexible for viewers For example it s tempting to set the column widths of a table with absolute widths It may look terrific on the designer s 17 inch screen but simply awful on a smaller 14 inch monitor not to mention PDAs and cell phones Instead of trying to exploit side effects of tags or tinkering with minute details in markup to ge the right effect designers now can work with a stylesheet Stylesheets typically are designed downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir with multiple purposes in mind For example typeface selection is flexible taking into account the capabilities of the reader s local system Stylesh
68. Without it the schema would allow no more than one such element A choice element is the opposite of all Instead of requiring all the elements to be present it will allow only one of the choices to appear In this case wanted at most one of junior or lt senior gt to appear set the minOccurs attribute in the choice to zero to make it optional You can choose to use junior Or lt senior gt but you don t have to Curiously there is no type for empty elements That s why had to define one emptyElem for the elements junior and senior This Is only scratching the surface of XML Schema which offers an enormous variety of features including type extension and restriction lists unions namespace features and much more For more information on XML Schema see Eric van der Vlist s XML Schema O Reilly amp Associates 2002 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 4 4 RELAX NG RELAX NG is a powerful schema validation language that builds on earlier work including RELAX and TREX Like W3C Schema it uses XML syntax and supports namespaces and data typing It goes further by integrating attributes into content models which greatly simplifies the structure of the schema It offers superior handling of unordered content and supports context sensitive content models In
69. XSLT and XPath On the Edge Jeni Tennsion M amp T Books An exploration of advanced XSLT and XPath techniques XPath and XPointer John Simpson O Reilly amp Associates An introduction to the XPath and XPointer specifications for addressing parts of XML documents XSL FO Dave Pawson O Reilly amp Associates An introduction to XSL Formatting Objects covering page layout techniques and stylesheet integration Definitive XSL FO G Ken Holman Prentice Hall Explores many different aspects and APIs of Java processing with XML Understanding XML Web Services Eric Newcomer Addison Wesley An introduction to the world of Web Services Web Services Essentials Ethan Cerami O Reilly amp Associates An introduction to the Web Services specifications including XML RPC SOAP 1 1 WSDL and UDDI Web Services and Perl Paul Kulchenko and Randy Ray O Reilly amp Associates A guide to using web services in a Perl environment downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir BEEP The Definitive Guide Marshall Rose O Reilly amp Associates A complete guide to the Blocks Extensible Exchange Protocol an IETF effort built on XML Programming Jabber D J Adams O Reilly amp Associates A guide to working with Jabber an instant messaging program and protocol built on XML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB A 3 St
70. You should use this method whenever you add new text nodes to ensure that the structure of the document remains the same without erroneous extra children getAttributeNS DOM 2 only Retrieves an attribute value based on its qualified name the namespace prefix plus the local name getAttributeNodeNS DOM2 only Gets an attribute s node by using its qualified name getElementsByTagNamesNS DOM2 only Returns a NodeList of elements among this element s descendants that match a qualified name hasAttribute DOM 2 only Returns true if this element has an attribute with a given name hasAttributeNS DOM 2 only Returns true if this element has an attribute with a given qualified name removeAttributeNS DOM2 only Removes and returns an attribute node from this element s list based on its namespace qualified name setAttributeNS DOM2 only Adds a new attribute to the element s list given a namespace qualified name and a value setAttributeNodeNS DOM 2 only Adds a new attribute node to the element s list with a namespace qualified name 10 9 1 9 Attr This kind of node represents attributes 10 9 1 9 1 Properties Here are the properties for the Attr class Dele The attribute s name Specified downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir True if the program or the document explicitly set the attribute If it was set in the DTD as a default and not reset anywhere else then it wi
71. ancestor or self appendix label gt lt xsl value of select ancestor or self appendix label gt lt xsl when gt lt xsl when test ancestor or self chapter gt xsl number format 1 value count preceding chapter 1 gt lt xsl when gt lt xsl when test ancestor or self appendix gt xsl number format A value count preceding appendix 1 gt lt xsl when gt xsl when test ancestor or self preface gt lt xslitext gt 0 lt xsl text gt lt xsl when gt lt xsl otherwise gt lt xsl text gt lt xsl text gt lt xsl otherwise gt lt xsl choose gt lt xsl template gt lt xsl template match figure title gt rosplock font size 8pt downloaded from fib ommolkcetftab ir downloaded from lib eommolketab ir font style italic Space after 2mm keep with next within page always lt xsl text gt Figure lt xsl text gt xsl call template name chapnum gt xsl text xsl text xsl number format 1 count figure from chapter appendix level any gt lt xsl text gt lt xsl text gt xsl apply templates Jto blogk lt xsl template gt lt i gt Caroch alli q sL a Small head gt lt xsl template match title gt Lo DLOCK font size 12pt font weight bold space after 4mm xsl apply templates cATOTE Lp lt xsl template gt Next follow a bunch of paragraph level blocks lt xsl template match para gt EIUTDIOSE Space aft
72. and villain are two such symbols called tags The data or content fills the space between these tags As you get used to looking at XML you ll use the tags as signpost to navigate visually through documents At the top of the document is the XML declaration xml version 1 0 gt This helps an XML processing program identify the version of XML and what kind of character encoding it has helping the XML processor to get started on the document It is optional but a good thing to include in a document After that comes the document type declaration containing a reference to a grammar describing document located on the system in the file xml resources dtds telegram dtd This is known as a document type definition DTD lt DOCTYPE gt is one example of a type of markup called a declaration Declarations are used to constrain grammar and declare pieces of text or resources to be included in the document This line isn t required unless you want a parser to validate your document s structure against a set of rules you provide in the DTD Next we see the telegram tag This is the start of an element We say that the element s name or type not to be confused with a data type is telegram or you could just call it a telegram element The end of the element is at the bottom and is represented by the tag lt telegram gt note the slash at the beginning This element contains all of the contents of the document No wonder t
73. and attributes put handles on data just as SQL tables use table and field names Element structure supplies even more information in the form of context e g element A is the child of element B which follows element C etc With a little knowledge of the markup language you can locate and extract any piece of information This is useful for many reasons First you might want to locate specific data from a known location called a path in a particular document Given a URI and path you ought to be able to fetch that data automatically The other benefit is that you can use path information to get really specific about processing a class of documents Instead of just giving element name or attribute value to configure a stylesheet as with CSS you could incorporate all kinds of extra contextual details including data located anywhere in the document For example you could specify that items in a list should use a particular kind of bullet given in a metadata section at the beginning of the document To express path information in a standard way the W3C recommends the XML Path Language also known as XPath Quickly following on the heels of the XML recommendation XPath opens up many possibilities for documents and facilitates technologies such as XSLT and DOM TheXML Pointer Language XPointer extends XPath into a wider realm allowing you to locate information in other documents Team LiB downloaded from lib ommolketab ir
74. are visible Control characters print as tt X tt for control X the delete character octal 0177 prints as tt tt Non ascii characters with the high bit set are printed as tt M tt for meta followed by the character for the low 7 bits lt dd gt lt dl gt lt p gt The lt i gt cat lt i gt utility exits 0 on success and amp gt 0 if an error occurs lt J p gt lt h2 gt BUGS lt h2 gt lt p gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Because of the shell language mechanism used to perform output redirection the command lt tt gt cat filel file2 amp gt filel lt tt gt will cause the original data in filel to be destroyed lt p gt lt h2 gt SEE ALSO lt h2 gt Gn lt li lt a hrefr he amp ad Html HHeadil a li lt li gt lt a hrefs more html omoreil s lri lt li gt lt a href pr html 5pr 1 a li lt li gt lt a hrerse tall hbml trallril ela lT lt li gt lt a hrefs vis html wlisil ms li lt 7 Use cus Rob Pike lt i gt UNIX Style or cat v Considered Harmful lt i gt USENIX Summer Conference Proceedings 1983 lt p gt lt i HISTOBRY hn3 lt p gt A lt i gt cat lt i gt utility appeared in Version 6 AT amp T UNIX lt I p lt p gt 3rd Berkeley Distribution May 2 1995 lt p gt lt j ody gt lt html gt This is a flat document structure No elements were used to contain and divide sections HTML
75. around an element that contains definable properties such as padding and margin widths See also presentation stylesheet Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB C candidate recommendation In the standards process a candidate recommendation is a specification that has achieved enough consensus by its working group to be released for public review See also recommendation standards body catalog A specially formatted text file usually local whose information is used to resolve public identifiers into system identifiers The catalog file format was formally specified by OASIS Technical Resolution 9401 1997 See also formal public identifier URI CDATA character data CDATA is an entity data type consisting of nonparsed characters Entity references included in this data will not be resolved A CDATA marked section looks like this lt CDATA unparsed content See also PCDATA character encoding The representation of characters as unique numbers in a character set See alsocharacter set character entity A notation for any character or symbol that uses its character set number or abbreviation The common syntax for character encoding is an ampersand amp followed by the name or a sign and number terminated with a semicolon For example the copyright symbol can be output in a document by using either amp 4169 Or amp copy character
76. between programs There are a variety of data binding implementations available largely for the Java and NET platforms Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Appendix A Resources The resources listed in this appendix can help you learn even more about XML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB A 1 Online XML com The web site http www xml com is one of the most complete and timely sources of XML information and news around It should be on your weekly reading list if you are learning or using XML XML org Sponsored by OASIS http www xml org has XML news and resources including the XML Catalog a guide to XML products and services The XML Cover Pages Edited by Robin Cover http xml coverpages org is one of the largest and most up to date lists of XML resources Cafe Con Leche Elliotte Rusty Harold provides almost daily news along with a quote of the day at http ibiblio org xml XMLHack For programmers itching to work with XML http www xmlhack com is a good place to go for news on the latest developments in specifications and tools DocBook OASIS the maintainers of DocBook have a web page devoted to the XML application at http www docbook org You can find the latest version and plenty of documentation here A Tutorial on Character Code Issues Juk
77. big table The Unicode Consortium s web page http www unicode org has a wealth of resources including character tables an FAQ and descriptions of related technologies In the decade it has been around Unicode managed to attract enough favorable attention to become a necessary component in the Internet Most operating systems ship with some support for Unicode including extensive font sets and Unicode cognizant web browsers and editing tools Most programming languages in use today support Unicode Java was designed from the start with downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Unicode support Others like Perl added support later And most important for readers of this book Unicode is the standard character set for XML 9 1 4 Common Encodings When choosing a character encoding for your document you must consider several things Do the constraints of your authoring environment require an 8 bit encoding or can you move up to 16 bits or higher Do you really need the high characters of Unicode or can you live with the limitations of a smaller set like ISO Latin 1 Do you have the fonts to support your encoding s character repertoire Does it support the byte order of your operating system In this section will present a few of the more common character encodings available and attempt to answer these questions for each 9 1 4 1 ISO 8859 ISO 8859 is a collection of 8 bit character encodings dev
78. bottom of the page A footnote also leaves behind a referential symbol to bring it to the attention of the reader Because of this unusual behavior XSL has devoted an FO specifically to footnotes The following template shows how to set up a formatting object for a footnote The first child of the object is an inline FO describing what to place in the main text as an indication of the footnote s existence in this case the number of the footnote in the chapter The second child contains the footnote body which will be positioned at the bottom of the page For convenience I ve used some list related elements to help format the footnote text with a number lt xsl template match footnote gt lt fo footnote gt lt fo inline font size 70 vertical align super xsl number count footnote from Chapter level any format 1 gt lt fo inline gt ero rootnote Dody amp ro lis5p Diogk roslist uatem space before 5mm downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir fo list item label end indent label end gt LOTDLOCK font size 7pt xsl number count 2 footnote from chapter level any format 1 gt erfosblock fo list item label fo list item body start indent body start SIOSDIOOKR font size 7pt xsl apply templates eJfosblocks fo list item body fo list item fo list block fo footnote body lt J TOL OOL thote lt xsl template
79. but decided to do it this way to show you how to declare empty elements Also using an element makes the markup less cluttered and we already have two attributes in the container element The first attribute declared is a requiredpid a person identification string Its type isID which to validating parsers means that it is a unique identifier within the scope of the document No other element can have an D type attribute with that value This means that if the census taker accidentally puts in a person twice the parser will catch the error and report the document invalid The parser can only check within the scope of the document however so there is nothing to stop a census taker from entering the same person in another document D type attributes have another limitation There is one identifier space for all of them so even if yot want to use them in different ways such as having an identifier for the address and another for people you can t use the same string in both element types A solution to this might be to prefix the identifier string with a code like HOME 38225 for address and PI D 489294 for person effectively creating your own separate identifier spaces Note that I D type attributes must always begin with a letter or underscore like XML element and attribute names The other attribute employed Is optional as denoted by the IMPLIED keyword It s also an enumerated type meaning that there is a set of allowed values
80. but the second one The fourth quotation element A number alone in the predicate is shorthand for position quotation type silly or The first third and fourth quotation elements The or Qtype wise keyword acts as a Boolean or operator Team LiB position last quotation 4 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 6 3 XPath Expressions Location paths are a subset of a more general concept called XPath expressions These are statements that can extract useful information from the tree Instead of just finding nodes you can count them add up numeric values compare strings and more They are much like statementsin a functional programming language There are five types listed here Boolean An expression type with two possible values true and false Node set A collection of nodes that match an expression s criteria usually derived with a location path Number A numeric value useful for counting nodes and performing simple arithmetic String A fragment of text that may be from the input tree processed or augmented with generated text Result tree fragment A temporary node tree that has its own root node but cannot be indexed into using location paths In XPath types are determined by context An operator or function can transform one expression type into another as needed For this reason there are well defined rules to determ
81. by using the operator instead of the equals sign This selector matches lt planet atmosphere breathable sweet dense gt Or planet atmos phere foggy sweet gt but it does not match lt planet atmosphere breathable stinky gt planet populace barbaric Similar to the item in list matching operator a selector with the operator matches an item in a hyphen separated value list provided it begins with the value in the selector This matche planet populace 2 barbaric hostile This kind of selector is often used to distinguish between language types The value of the XML attribute xml lang is a language identifier a string that looks like this en us The two character code en stands for English and the code US qualifies the United States variant To match a planet element with an xml lang attribute that specifies English use the selector planet language en This selects both en US and en UK planet atmosphere breathable populace friendly Selectors can string together multiple attribute requirements To match the attribute selectors must be satisfied just as if they were bound with a logical AND operator The above selector matches planet atmosphere breathable populace friendly gt but not planet populace friendly gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir mars This special form is used to match rp attributes It matches planet id ma
82. category food gt lt amount gt 24 30 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 15 lt day gt lt date gt lt payto gt Johnny Rockets lt payto gt lt description gt lunch lt description gt lt debit gt lt checkbook gt Each record is either a debit expense or a deposit income It contains information about the expense income category to whom paid money or received money from the date it happened and a brief description have used documents like this to balance my checkbook and summarize expenses in tables so can figure out where all my money goes How can you do this I ll show you a quick program you can write in Perl to calculate the ending balance in the previous example Example 3 2 shows a program that spits out a number on the command line Example 3 2 A tabulate program t usr bin perl use XML LibXML downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir my Sparser new XML LibXML my doc S parser parse file shift ARGV my Sbalance doc gt findvalue checkbook balance start foreach my record doc findnodes debit Sbalance Srecord gt findvalue amount j foreach my record doc findnodes deposit Sbalance Srecord gt findvalue amount j print Current balance balance Wn The library XML LibXML parses the document and stores it in an object tree cal
83. column object can be used to define group behavior of each column table cell The innermost table component Cells stack along the inline progression direction inside rows A cell may take up more than one column width or row height by setting thenumber columns spanned Or number rows spanned properties to a value greater than 1 Figure 8 10 outlines the structure of a typical table Figure 8 10 The structure of tables Lable with caption table table table cell e table row table cell tablecell table row table cell tahle call Properties common to all the table components include height and width which are useful in tuning the size of the areas they control Border properties also apply making it easy to create rules The following XSLT templates are my attempt to handle CALS tables the standard adopted by DocBook They allow for tables that have captions but no cell spans are allowed lt xsl template match table gt rostable with caprtion xsl apply templates fo table with caption lt xsl template gt lt xsl template match table title gt lt fo table caption font size 8pt font style italic downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Space after 2mm lt xsl text gt Table lt xsl text gt xsl call template name chapnum gt lt xsl text gt lt xsl text gt xsl number format 1 count table from chapter appendix level any
84. conditional sections to allow the maximum level of customization For example the DocBook XML DTD Version 1 0 includes the following lt ENTITY screenshot content module INCLUDE gt l screenshot content module lt ENTITY screenshot module INCLUDE gt lt S screenshot module lt ENTITY local screenshot attrib gt lt ENTITY screenshot role attrib Srole attrib gt lt ELEMENT screenshot screeninfo graphic graphicco gt lt ATTLIST screenshot downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir ecommon artrrib screenshot role attrib Slocal screenshot attrib gt lt end of screenshot module gt gt lt ENTITY screeninfo module INCLUDE lt Sscreeninfo module lt ENTITY local screeninfo attrib T gt lt ENTITY screeninfo role attrib Srole attrib gt lt ELEMENT screeninfo para char mix lt ATTLIST screeninfo 5 common attrib S6screeninfo role attrib Slocal screeninfo attrib gt lt end of screeninfo module l end of screenshot content module 5 The outermost conditional section surrounds declarations forscreenshot and also screeninfo which occurs inside it You can completely eliminate bothscreenshot and screeninfo by setting screenshot content module to IGNORE In your local DTD before the file is loaded Alternatively you can turn off only the section around the screeninfo declarations
85. contemt The content of this flow is a single block It sets a sans serif font of 8 points aligned to the left and a thin rule underneath The text to be displayed here is taken from the metadata block the content of a sourceDesc element i e the source of the document This is followed by the body flow object fo flow flow name xsl region body downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir font family didot serif fFont size 10pt xsl apply templates select teiHeader title gt xsl apply templates select teiHeader author gt xsl apply templates select text body gt Jrforrlowo fo page sequence lt xsl template gt The main flow formats the title author and finally the body of the document withapply templates Statements All that remains is to write templates for the other element types we wish to format These are included in the complete XSLT stylesheet listing inExample 8 3 Example 8 3 XSLT stylesheet for the TEI XML document lt xml version 1 0 gt xsl stylesheet xmlns xsl http www w3 org 1999 XSL Transform xmlns fo z http www w3 org 1999 XSL Format version 0 gt xsl output method xm1 gt lt l Start the FO tree and layout the page gt lt xsl template match gt SIO roO C lt fo layout master set gt lt fo simple page master master name the only page type page height 1lin page width 8 51in margin top
86. digits to put in a group The following would result in the text1 0000 0000 xsl number value 100000000 grouping separator grouping size 4 An interesting feature of number Is its ability to count nodes The count attribute specifies the kind of node to count Say you wanted to print the title of a chapter with a preceding number like this lt hl gt Chapter 3 Bouncing Kittens lt hl1 gt Perhaps you could use this template lt xsl template match chapter title gt lt xsl text gt Chapter lt xsl text gt lt xsl value of select count preceding sibling chapter 1 gt lt xsl text gt lt xsl text gt lt xsl value of select 7 gt lt xsl template gt That will work but it is a little difficult to read Instead you can write it like this lt xsl template match chapter title xsl text Chapter xsl text xsl number count chapter format 1 gt lt xsl value of select gt lt xsl template gt count looks only at nodes that are siblings If you want to count nodes that may appear at different levels you need to add more information The attributelevel determines where to look for matching nodes It has three possible values single multiple and any If single Is selected the default the XSLT engine looks for the most recent ancestor that matches the pattern in the count attribute Then it counts backward among nodes at the same level With the value multiple selected all mat
87. document more readable to the human eye Take out this visual padding and your eyes will get tired very quickly So why not add some spaces here and there where it will help One important issue is how whitespace should be treated by XML software At the parser level whitespace is always passed along with all the other character data to the application level of the program However some programs may then normalize the space This process strips out whitespace in element only content and in the beginning and end of mixed content It also collapses a sequence of whitespace characters into a single space If you want to prevent a program from removing any whitespace characters from an element you downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir can give it a hint in the form of the xm1 space attribute If you set this attribute to preserve XML processing software is supposed to honor the request by leaving all whitespace characters intact Consider this XML encoded haiku poem xml space preserve gt A wind shakes the trees An empty sound of sadness The file l8 nor here lt poem gt took some poetic license by putting a bunch of spaces in there Hey it s art So how do I keep the XML processor from throwing out the extra space in its normalization process gave thepoem element an attribute named xml space and set its value to preserve In Chapter 4 I ll show you how to make this the standard
88. documents of any kind SyncML is a way to transfer data from a personal computer to a smaller device like a cellular phone giving you a fast and dependable way to update address lists and calendars Transformation Converting between one format and another is a necessary fact of life If you ve ever had to import a document from one software application into another you know that it can sometime be a messy task Extensible Style Language Transformations XSLT can automate the task for you It turns one form of XML into another in a process calledtransformation It is essentially a programming language but optimized for traversing and building XML trees Transformation is the topic of Chapter 7 Development When all else fails you can always fall back on programming Most programming languages have support for parsing and navigating XML They frequently make use of two standard interfaces The Simple API for XML SAX is very popular for its simplicity and efficiency The Document Object Model DOM outlines an interface for moving around an object tree of a document for more complex processing Programming with XML will be the last topic visited in this book in Chapter 10 This list demonstrates that XML has worked well as a basis for information exchange and application in a variety of fields downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LIB downloaded from lib ommolketab ir downl
89. downloaded from fib ommolkcefab ir Team LiB 1 3 What Can Do with XML Let me tackle that question by sorting the kinds of problems for which you would use XML 1 3 1 Store and Retrieve Data Just about every software application needs to store some data There are look up tables work files preference settings and so on XML makes it very easy to do this Say for example you ve created calendar program and you need a way to store holidays You could hardcode them of course but that s kind of a hassle since you d have to recompile the program if you need to add to the list So you decide to save this data in a separate file using XML Example 1 4 shows how it might look Example 1 4 Calendar data file lt Caldata gt lt holiday type international gt lt name gt New Year s Day lt name gt lt date gt lt month gt January lt month gt lt day gt 1 lt day gt lt date gt lt holiday gt lt holiday type personal gt lt name gt Erik s birthday lt name gt lt date gt lt month gt April lt month gt lt day gt 23 lt day gt lt date gt lt holiday gt lt holiday type national gt lt name gt Independence Day lt name gt lt date gt lt month gt July lt month gt lt day gt 4 lt day gt lt date gt lt noliday gt holiday type religious gt lt name gt Christmas lt name gt lt date gt lt month gt December lt month gt lt day gt 25 lt day gt lt date gt lt holiday gt lt caldata gt Now a
90. downloaded from fib ommolkcefab ir Team LiB markup A collection of characters that group organize and label the pieces of content in a document Markup tags are interspersed within the content as instructions to the parser which removes them as it builds a document data structure in memory Markup includes start and end tags for elements entity references declarations comments processing instructions and marked sections See also element tag markup language A set of formal rules for representing data and encoding structures that surround the data A document that obeys the rules of the markup language is said to be well formed A markup language provides ways to label parts using elements to enforce structure using a DTD and tc import data with entity references XML is not itself a markup language but a set of rules for creating markup languages See also application DTD markup metadata Descriptive data that is not directly included in the content of a document For example a document s creation date or author is metadata See also document markup mixed content A mixture of elements and character data that can be specified as valid content for an element via its content model See also CDATA content content model element modular DTD A DTD that is divided into logical pieces allowing for easy maintenance and selection of only the modules required in a document The modules of a modular DTD are often kep
91. downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Sparser gt load_ext_dtd 1 read the external DTD my doc S parser gt parse_file shift ARGV parse the file if 0 test for errors print STDERR PARSE ERRORS n Q else print The document file is valid n j XML LibXML IS an interface to a C library called libxml2 where the real parsing work is done There are libraries for Java C Python and almost any other programming language you can think of The parser in the this example goes beyond just well formedness checking It s called avalidating parser checks the grammar types and order of elements of the document to make sure it is a valid instance c document type For example could have it check a document to make sure it conforms to the DTD for To do this need to place a line in the XML document that looks like this CHDLCITPE Dem SUED aa Cugat This tells the parser that it needs to find a DTD read its declarations and then be mindful of element ty usage as it parses the document The location of the DTD is specified in two ways The first is thepublic inside the first set of quotes above This is like saying go and read the Magna Carta which is an unan command but still requires you to hunt around for a copy of it In this case the parser has to look up t location in a concordance called a catalog Your program has to tell the parser where to find a catalo
92. downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir You can t nest CDATA sections because the closing gt of the nested CDATA section will be treated as the end of the first CDATA section Because of its role in CDATA sections you also can t use an unescaped gt anywhere in XML document text 2 6 3 Processing Instructions Presentational information should be kept out of a document whenever possible Still there may be times when you don t have any other option for example if you need to store page numbers in the document to facilitate generation of an index This information applies only to a specific XML processor and may be irrelevant or misleading to others The prescription for this kind of information Is a processing instruction It is a container for data that is targeted toward a specific XML processor Processing instructions Pls contain two pieces of information a target keyword and some data The parser passes processing instructions up to the next level of processing If the processing instruction handler recognizes the target keyword it may choose to use the data otherwise the data is discarded How the data will help processing is up to the developer A PI shown in Figure 2 23 starts with a two character delimiter 1 followed by a target 2 an optional string of characters 3 that is the data portion ofthe PI and a closing delimiter 4 Figure 2 23 Processing ins
93. element ns http fakesite org xmlns http relaxng org ns structure 1 0 gt lt nsName gt lt empty gt lt element gt If you don t want to let everything through trim down the set using except Use it as a child to anyName Or nsName to list classes of elements or attributes you don t want to allow Here only elements not in the current namespace are declared empty lt element ns http fakesite org xmlns http relaxng org ns structure 1 0 lt anyName gt SEKOPE lt nsName gt except lt anyName gt lt empty gt lt element gt The only place you cannot use a name class is as the child of adefine element This is wrong define name too ambiguous gt lt anyName gt lt define gt We ll discuss define elements in the next section As this book was going to press James Clark announced the Namespace Routing Language NRL which provides enormous flexibility for describing how content in different namespaces should be validated and processed See http www thaiopensource com relaxng nrl html for more information and an implementation 4 4 6 Named Patterns downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The patterns we have seen so far are monolithic All the declarations are nested inside one big one This is fine for simple documents but as complexity builds it can be hard to manage Named patterns allow you to move declarations outside of the main
94. elements by adding a name prefix to distinguish between XSLT commands and the markup to be output For every element type in the source document s markup language there is a corresponding rule in the stylesheet describing how to handle it don t expect you to understand this code right now There is a whole chapter on XSLT Chapter 7 after which it will make more sense to you Example 1 6 An XSLT script for telegram documents esxeclcrtransrora xmlns xsl http www w3 org 1999 XSL Transform version 1 0 gt lt KOoLitemplate matoy relegram gt lg wa lt head gt lt title gt telegram lt title gt lt head gt SIQUIS lt div style 2 background color wheat padding lem gt lt hl gt telegram lt h1 gt xsl apply templates div lt body gt lt html gt lt xsl template gt lt xsl template match from gt lt h2 gt lt xsl text gt from xsl text xsl apply templates h2 lt xsl template gt lt xsl template match to gt lt h2 gt lt xsl text gt to lt xsl text gt lt xsl apply templates gt lt h2 gt lt xsl template gt lt xsl template match subject gt lt h2 gt lt xsl text gt subj lt xsl text gt lt xsl apply templates gt lt h2 gt lt xsl template gt downloaded from lib ommolketab ir downloaded from lib ommolketab ir exsicLemplarte matecn message blockquote font style font family monospace gt xsl apply templates CITODES lt block
95. elements instead Lean lt person gt sue lt person gt lt person gt joe lt person gt lt person gt jane lt person gt lt team gt In a DTD attributes can be declared to be of certain types An attribute can have an enumerated value Meaning that the value must be one of a predefined set Or it may have a type that registers as a unique identifier no other element can have the same value It may be an identifier reference type requiring that another element somewhere has an identifier attribute that matches A validatinc parser will check all of these attribute types and report deviations from the DTD I ll have more to sa about declaring attribute types in Chapter 4 Some attribute names are reserved in XML Typically they start with the prefix xml such as xmlns To avoid a conflict choose names that don t start with those letters 2 4 3 Namespaces Namespaces are a mechanism by which element and attribute names can be assigned to groups They are most often used when combining different vocabularies in the same document as did in Chapter 1 Look at that example and you ll see attributes in some elements like this one math xmlins http www w3 org 1998 Math MathML gt Example 2 2 is another case The part catalog element contains two namespaces which are declared by the attributes xmlns nw and xmlns The elements inside part catalog and their attributes belong to one or the other namespace Those in the f
96. embedded programming languages like JavaScript and Java While XLink was slowly wending its way through the standards process browser vendors quickly added support for various coding platforms to enable all kinds of stunts including many of the problems XLink was meant to solve Had XLink appeared sooner its chances for success might well have been better and Suspect it would have saved a lot of headaches for web site developers All programming languages yes even Java are platform dependent solutions They don t always work as expected and they aren t well suited to archiving information for a long period of time Perhaps XLink is an example of when the standards process does not work as advertised Instead of inspiring developers to adopt a best practice all it managed to inspire was a collective yawn Whether it s because the recommendation fails to address the problem adequately or it clashes with the marketing plans of commercial developers or the new functionality does not justify the effort to implement it these things do happen 6 4 1 Syntax The following is an example of anxpointer pointer ict loopy 7 child para 2 If successful it will return a nodecorresponding to the second para child of the element whose id attribute has the value flooby If unsuccessful it will return an empty location set 6 4 1 1 Schemes and chained xpointers The keyword xpointer IS called a scheme which serves to identi
97. end Figure 1 9shows how it looks ir browser Example 1 9 A document composed of XHTML SVG and MathML lt xml version 1 0 gt lt html xmilns http www w3 org 1999 xhtml lt head gt title T E L E GR A M lt title gt lt CSS stylesheet gt lt style gt body background color tan font family sans serir telegram border thick solid wheat message color maroon j head i1 color blue name font weight bold color green villain font weight bold color red lt style gt lt head gt lt poay gt lt div class telegram gt lt hl gt Telegram lt h1 gt lt h2 gt lt span class head gt To lt span gt Sarah Bellum lt h2 gt lt h2 gt lt span class head gt From lt span gt Colonel Timeslip lt h2 gt lt h2 gt lt span Glass head Subj span RBobot sitting inst ructions lt h2 gt SVG Picture of Zonky gt svg xmins http www w3 org 2000 svg width 100 height 100 gt rect x 5 y 5 width 90 height 95 fill none stroke black stroke width 1 gt downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir rect x 25 y 75 width 50 height 25 Stroke Diack Stroke widths 2 s lt rect x 30 y 70 width 40 height 30 fill gray fill blue SLtrOoksseUhlack stroko width 2 gt circle cx 50 cy 50 r 20 fill 2 blue stroke black stroke width 2 gt circle cx 43 c
98. ending tag mismatch announcement and announcement lt anouncement gt It caught two mismatched tags and an illegal character And not only did it tell me what was wrong it showed me where the errors were so can go back and correct them more easily Checking if a document is well formed can pick up a lot of problems e Mismatched tags a common occurrence if you are typing in the XML by hand The start and enc tags have to match exactly in case and spelling e Truncated documents which would be missing at least part of the outermost document both start and end tags must be present e Illegal characters including reserved markup delimiters like lt gt and amp There is a special syntax for complex or reserved characters which looks like amp 1t for If any part of that is missing the parser will get suspicious Parsers should also warn you if characters in a particular encoding are not correctly formed which may indicate that the document was altered in a recent transmission For example transferring a file through FTP as ASCII text can sometimes strip out the high bit characters The well formedness check has its limits The parser doesn t know if you are using the right element in the right places For example you might have an XHTML document with ap element inside the head Which is illegal To catch this kind of problem you need to test if the document is a valid instance of XHTML The tool for this is avalidating
99. expected situation Is it generic enough to support different formatting options and modes Your decisions will help answer the most basic question which is how can you represent a piece of information as XML This problem is part of the important topic of data modeling In this chapter we look at the ways in which different kinds of data are modelled using XML First I l show you the most basic kinds of documents simple collections of preferences for software applications The next category covers narrative documents with characteristics such as text flows block and inline elements and titled sections Lastly under the broad umbrella of complex data I l talk about the myriad specialized markup languages for everything from vector graphics to remote procedure calls Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 3 1 Simple Data Storage XML can be used like an extremely basic database Since the early days of computer operating systems data has been stored in files as tables like the venerable etc passw d file nobody 2 2 Unprivileged User nohome noshell root s0 0 System Administratori var root i bin tesh daemon 1 1 System Services var root noshell smmsp 25 25 Sendmail User private etc mail noshell Data like this isn t too hard to parse but it has problems too Certain characters aren t allowed Eacl record lives on a separate line so data can t span l
100. flexible set of tests for document structures Schematron offers precision and customizable error reporting though that precision can sometimes lead to very verbose schemas As a result Schematron is typically used to supplement RELAX NG or W3C XML Schema rather than to replace them Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 2 Linking XLink XML Linking Language creates links between resources W3C Status XLink became a W3C Recommendation in June 2001 The specification is published at http www w3 org TR xlink Description XLink allows elements to be inserted into XML documents that create and describe links between resources t uses XML syntax to create structures to describe links from the simple unidirectional hyperlinks of today s HTML to more sophisticated links XML Base XML Base provides a facility for defining base URIs for parts of XML documents W3C Status XBase became a W3C Recommendation in June 2001 The specification is published at http www w3 org TR xmlbase Description XML Base describes a mechanism for providing base URI services to XLink The specification is modular so that other XML applications can make use of it XI nclude downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XML Inclusions is a standard for embedding XML documents W3C Status XI nclude became a Candidate R
101. for elements that are right next to each other there may be text in between but no other elements downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir You can select parts of an element s content with pseudo element selectors first line applies to the first line of an element as it appears in a browser This may vary since the extent of the line depends on unpredictable factors such as window size With this selector we can set the first line of a paragraph to all caps achieving a nice stylistic effect to open an article This rule transforms the first line of the first para of a chapter to all capitals chapter gt para first child first line text transform uppercase In a similar fashion irst letter operates solely on the first letter in an element s content as wel as any punctuation preceding the letter within the element This is useful for drop caps and raised capitals Dody c pitirstohslg4itirste bLsetrter 4 font size 300 Iont color red With the pseudo classes before and after you can select a point just before or just after an element respectively This is most valuable for adding generated text character data not present in the XML document Figure 5 8 illustrates the following example Warning gt Irirst ohnrldiDerore T content WARNING font weight bold color red Figure 5 8 Autogenerated text in an admonition object 5 3 4 Resolving Property Conflicts
102. from lib ommolketab ir downloaded from fib ommolkcefab ir for computer processing Extracting data from deep inside a document is a common task for developers DOM and SAX are often for a simple query like this XPath is a shorthand for locating a point inside an XML document It is used and also in places like XSLT and some DOM implementations to provide a quick way to move around a C XPointer extends XPath to create a way to specify the location of a document anywhere on the Internet the notion of URLs you know from thea element in HTML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 2 Markup and Core Concepts There s a Far Side cartoon by Gary Larson about an unusual chicken ranch Instead of strutting around pecking at seed the chickens are all lying on the ground or draped over fences as if they were made of rubber You see it was aboneless chicken ranch Just as skeletons give us vertebrates shape and structure markup does the same for text Take out the markup and you have a mess of character data without any form It would be very difficult to write a computer program that did anything useful with that content Software relies on markup to label and delineate pieces of data the way suitcases make it easy for you to carry clothes with you on a trip This chapter focuses on the details of XML markup Here will describe the fundamental building
103. gives you two ways to combine stylesheets inclusion and importing Including a stylesheet means inserting its contents directly into the target stylesheet All the rules and directives will be treated as if they were in your stylesheet all along Theinclude element has an href attribute which holds a URI for the stylesheet to include You can insert this element anywhere in your stylesheet as long as it isn t inside a rule The levels of presentness of incoming templates are not the same when they areimported Templates in the original stylesheet always override templates in the imported one no matter what their priority The element import also uses an href attribute to specify a stylesheet but it can be placed only at the very top of the stylesheet before any other rules or directives The advantage of this weaker form of merging is that it can override parts of a more complete set of rules to customize the results While include pours rules in at the same level of precedence as your own import gives you more control over the remote set allowing you to pick and choose among rules There may be times when you want to override your own rules in favor of those that are imported foi a localized region The element apply imports is analogous to apply templates except that it considers only imported rules and ignores those that are physically present Also it only operates or downloaded from lib ommolketab ir downloaded from fib
104. gt 8 6 7 Tables Tables are very intuitive in XSL Virtually anything you want to do in a table is possible The following FO types are used to build tables table and caption A block encapsulating a table and its caption table caption A block containing text describing the table table The container of basic table components Its children include a number oftable column objects an optional table header an optional table footer and at least one table body table column An informational element describing details about a column such as its width Set thecolumn number property to a positive integer to refer to a specific column A column is a stack of cells perpendicular to the inline propagation direction table body A collection of table row objects Rows stack in the block progression direction table header An optional container of rows or cells that must appear before the body This is traditionally where column heads reside table footer Like cable header except that it must appear after the body Typically used for things like column totals downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir table row A block containing some number oftable cells Usually the number of cells is constant for al rows in the table and the formatter will attempt to align them so that their edges parallel to the block progression direction line up These lined up cells are called columns and atable
105. have to insert tests everywhere and the code would get ugly quickly A better solution is provided by pull parsing This example uses the XMLPULL API see http www xmlpull org in a recursive descent style of processing import org xmlpull vl xmlLPull Parser INDOP L OXq Ekxmlz 10 7 import gQrg nmipull vi import JEYSL ICO 3 import Java uHLni1L vVector downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir public class test 4 publie statio void main String args throws IOException XmlPullParserException Vector products new Vector Ley i XmlPullParser parser new KXmlParser parser setInput new FileReader args 0 parser nextTag parser requireiAmilPHLlParBSer bolIART JAG null Gacalog 7 while parser nextTag XmlPullParser END TAG Product newProduct readProduct parser producLts addinewProduct j parser requirfeiAnlPullPadrser BbND TAG DELL ostalog j parser next Perser require ml PullParser ND DOCUMENT mull mull catch Exception e e printStackTrace ovsrem ogtpriuHLlni Products int count products size ror int 1903 IS O0DOUunLE i447 4 Product report Product products get 1 oysten our prantin Namei T report name 37 ovetem out prantlnid Price Mreporrtprioe J Static public Product readProduct XmlPullParser parser throws IOException XmlPullParserException Vector products new Vector par
106. hierarchical structures HTML human documents hybrids hypertext standards Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir Team LiB A B C D E F G H EH J K L EM EN O P IQ R S T U V W X importing definitions DTDs modules indentation indices points inheritance CSS properties properties inline elements inlines 2nd 3rd See also blocks 4th areas DocBook formatting progression direction instances integrity interaction interfaces APIs SAX XPath as class references DOM internal entities internal subsets 2nd 3rd internationalization characters encoding references selecting encodings Unicode human languages specifying MI ME ISO International Standards Organization ISO 8859 Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LIB A B C D E F EG H 1 J K L M EN O P Q R S ET U V W X Java SAX Simple API for XML 2nd DOM Java DOM Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LIB A B C D E F G EH 1 J EK L M N O P Q R S T U V W X Konquerer Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E F G H 1 J K L EM EN O
107. improve upon DTDs they will always have limitations of one sort or another e Schemas can be obstacles for authors In spite of advances in XML editors with fancy graphical interfaces authoring in XML will never be as easy as writing in a traditional word processor Time spent thinking about which element to use in a given context is time not spent on thinkinc about the document s content which is the original reason for writing it Some editors supply a menu of elements to select from that changes depending on the context Depending on the language and the tools it still can be confusing and frustrating for the lay person e You have to maintain it With a schema you have one more tool to debug and update Like downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir software it will have bugs versions and even its own documentation It s all too easy to damage a schema by deleting an imported component or introducing a syntax error Older documents may not validate if you update the schema forcing you to make retroactive changes to them One silver lining is that except for DTDs most schema languages are based on XML which allows you to use XML editors to make changes e Designing it will be hard Schemas are tricky documents to compose You have to really think about how each element will fit together what kinds of data will be input whether there are Special cases to accommodate If you re just starting out
108. in fiscal quarter Q3 is generally good Sales of amp bobco bolts increased 35 over this time a year ago lt par gt lt par gt amp bobco has been supplying high quality bolts to contractors for over a century and amp bobco is recognized as a leader in the construction grade metal fastener industry lt par gt press release The entity amp bobco appears in the document five times If you want to change something about the company name you only have to enter the change in one place For example to make the name appear inside a companyname element simply edit the entity declaration CINMNIITY DODGO lt companyname gt Bob s Bolt Bazaar Inc lt companyname gt gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir When you include markup in entity declarations be sure not to use the predefined character entities e g amp 1t and amp gt to escape the markup The parser knows to read the markup as an entity value because the value is quoted inside the entity declaration Exceptions to this are the quote character entity amp quot and the single quote character entity amp apos If they would conflict with the entity declaration s value delimiters then use the predefined entities e g if your value is in double quotes and you want it to contain a double quote Entities can contain entity references as long as the entities being referenced have been declared previously Be careful not to
109. include references to the entity being declared or you ll create a circulat pattern that may get the parser stuck in a loop Some parsers will catch the circular reference but it IS an error 2 5 2 2 External entities Sometimes you may need to create an entity for such a large amount of mixed content that it is impractical to fit it all inside the entity declaration In this case you should use anexternal entity an entity whose replacement text exists in another file External entities are useful for importing content that is shared by many documents or that changes too frequently to be stored inside the document They also make it possible to split a large monolithic document into smaller pieces that can be editec in tandem and that take up less space in network transfers External entities effectively break a document into multiple physical parts However all that matters to the XML processor is that the parts assemble into a perfect whole That is all the parts in their different locations must still conform to the well formedness rules The XML parser stitches up all the pieces into one logical document with the correct markup the physical divisions should be irrelevant to the meaning of the document External entities are a linking mechanism They connect parts of a document that may exist on other systems far across the Internet The difference from traditional XML links XLinks is that for external entities the XML processor must i
110. interpret that string as the enc of the comment Figure 2 21 Comment syntax Comments can go anywhere in your document except before the XML declaration and inside tags The XML processor removes them completely before parsing begins So this piece of XML lt p gt The quick brown fox jumped test gt over the lazy dog The quick brown test gt fox jumped over the lazy dog The lt Let 2o murpgk brown tox jumped over the lazy dog lt p gt will look like this to the parser lt p gt The quick brown fox jumpedover the lazy dog Ihe quick brown fox jumped over the lazy dog Thequick brown fox jumped over the lazy dog lt p gt Since comments can contain markup they can be used to turn off parts of a document This is downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir valuable when you want to remove a section temporarily keeping it in the file for later use In this example a region of code is commented out lt p gt Our store is located at lt p gt Spese lt address gt 59 Sunspot Avenue lt address gt lt address gt 210 Blather Street lt address gt When using this technique be careful not to comment out any comments i e don t put comments inside comments Since they contain double dashes in their delimiters the parser will complain when it gets to the inner comment 2 6 2 CDATA Sections If you mark up characters frequently in your text you may find it
111. into it This process continues until all the objects from all flows have been used up How flows are applied to regions is determined by aflow map Each region defined in a page master has a region name property This is a unique identifier that distinguishes the region in the page master Every flow must announce where it is to be placed by setting a 1ow name attribute with one of the declared region names The flow map is the implicit connection between flow names and region names In future versions of XSL this model is expected to change to make the flow map a separate object Regions have default values for region names corresponding to the names of their FOs For example the body region is named xsl region body unless you override that with a name of your own 8 4 3 Blocks Block level FOs are the objects that fill a flow Each block has at least one area to control For example a paragraph in a document will map to a block object in the FO tree It will stack inside the flow as a single area with a margin padding font and other properties Some properties that are common in all blocks can be categorized in these groups background border fonts margin and padding We will look at these groups now in more detail 8 4 3 1 Spacing properties CSS gives you two ways to add space to a block Padding pushes children further inside and margin pushes the block away from other blocks In XSL FO the paddingproperty is still here and th
112. invisible and so will not change the appearance of your document However it help to disambiguate whether the encoding is big endian or little endian Transpose the bytes and you wil get U FFFE which is not a valid Unicode character This simple test gives a quick and automatic way to determine the endian ness of the file UCS 2 and UCS 4 and even UTF 16 have not been that widely deployed because for Western alphabets where most characters can be encoded within 8 bits it effectively doubles the size of every file Another and perhaps more worrisome reason is that most software was written to handle text with one byte characters Running these programs on multibyte characters can have unpredictable even dangerous results Most low level routines in Unix are written in C and read 8 bitcnar datatypes Certain bytes have special meaning such as in filenames and 0 as a stream terminator When the program reads in a wide UCS character as a sequence of bytes one of those bytes may map to a control character and then who knows what could happen A better alternative is an encoding that passes through 8 bit systems unmolested yet retains the information of Unicode high characters Both of these requirements are satisfied by UTF 8 9 1 4 3 UTF 8 The UCS Transformation Format for 8 bits UTF 8 was developed by the X Open Joint Internationalization Group XOJIG in 1992 and later included in both the Unicode and UCS standards It is particul
113. ir Team LiB 1 4 How Do I Get Started By now you are chomping at the bit eager to gallop into XML coding of your own Let s take a look at hc your own XML authoring and processing environment 1 4 1 Authoring Documents The most important item in your XML toolbox is the XML editor This program lets you read and compos often comes with services to prevent mistakes and clarify the view of your document There is a wide sc quality and expense in editors which makes choosing one that s right for you a little tricky In this sectii you on a tour of different kinds Even the lowliest plain text editor is sufficient to work with XML You can use Text Edit on the Mac Not WordPad on Windows or vi on Unix The only limitation is whether it supports the character set used by document n most cases it will be UTF 8 Some of these text editors support an XML mode which car markup and assist in inserting tags Some popular free editors include vim elvis and my personal favo emacs is a powerful text editor with macros and scripted functions Lennart Stafflin has written an XML called psgml available at http www lysator liu se lenst It adds menus and commands for inserting showing information about a DTD It even comes with an XML parser that can detect structural mistakes editing a document Using psgml and a feature called font lock you can set upxemacs an X Window emacs to highlight markup in color Figure 1 5is a sna
114. key gt lt real gt 0 0 lt real gt lt key gt DeviceLevels lt key gt lt array gt lt real gt 1 lt real gt lt real gt 1 lt real gt array lt key gt Level lt key gt lt real gt l lt real gt edet cToaiot lt 7 hei eim SU dict lt plist gt http www apple com In this example the structure is recursive Adict can be a value allowing you to associate a key with a whole set of settings This allows for better organization by creating categories likeDevices and under that subcategories like InputDevices and OutputDevices Notice also the array type which associates multiple values to one key Here arrays are used to set the left and right volume levels really like this way of storing preferences because it gives me two ways to access the data can fiddle with settings in the program s preferences window The program would then update this XML file the moment click on the OK button Alternatively can edit the file myself This may be an easier way to affect changes especially if some features aren t addressed in the GUI can edit it in i text editor or in the special application included withthe Macintosh OS called Property List Editor whose interface is very easy to use as shown inFigure 3 1 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Figure 3 1 Apple s Property List Editor eot com apple soundpref plist Newsibling Delete 5 Dump Prop
115. kind of like the plethora of Unix flavors out today they seem much alike but have some big differences under the surface 10 8 1 Drivers SAX describes a universal interface that any SAX aware program can use no matter where the data is coming from Figure 10 1 shows how this works Your program is at the right It contacts the ParserFactory object to request a parser that will serve up a stream of SAX events The factory finds a parser and starts it running routing the SAX stream to your program through the interface Figure 10 1 ParserFactory downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The workhorse of SAX is the SAX driver ASAX driver is any program that implements the SAX2 XMLReader interface It may include a parser that reads XML directly or it may just be a wrapper for another parser to adapt it to the interface It may even be a converter transmuting data of one kind say SQL queries into XML From your program s point of view the source doesn t matter because it is all packaged in the same way The SAX driver calls subroutines that you supply to handle various events Thesecall backs fall into four categories usually grouped into objects e Document handler e Entity resolver e DTD handler e Error handler To use a SAX driver you need to create some or all of these handler classes and pass them to the driver so it can call their call back routines The document handler is the minim
116. language is flexible enough to reach any node in the target document XPointer actually goes further than XPath In addition to nodes it has two new location types Apoint is any place inside a document between two adjacent characters Whereas XPath would only locate an entire text node XPointer can be more granular and locate a spot in the middle of any sentence The other type introduced by XPointer is arange defined as all the XML information between two points This would be useful for say highlighting a region of text that may start in one paragraph and end in another Because of these new types the return value of an XPointer is not a node set as Is the case with XPath expressions Instead it is a more generallocation set where a location is defined as a point range or node A point is represented by a pair of objects a container node the closest ancestor element to the point and a numericindex that counts the number of characters from the start of container node s content to the point A range is simply two points and the information inside it is called a sub resource The XPointer specification makes no attempt to describe the behavior of an xpointer It simply returns a list of nodes or strings to be processed leaving the functionality up to the developer This i a good thing because XPointer can be used in many different ways When used in XLink the information it describes may be imported into the source target or left unlo
117. later processing They may seem like magic but transformations are a very powerful and not too complicated way to squeeze more use out of your XML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 7 1 History In the very early days of markup languages the only way to transform documents was by writing a custom software application to do it Before SGML and XML this was excruciating at best Presentational markup is quite difficult to interpret in any way other than the device dependent behavior it encodes SGML made it much easier for applications to manipulate documents However any transformation process was tied to a particular programming platform making it difficult to share with others The SGML community really needed a portable language specifically designed to handle SGML transformations and which supported the nuances of print publishing the major use of SGML at the time The first solution to address these needs was the Document Style Semantics and Specification Language DSSSL DSSSL pronounced dissel was completed in 1996 under the auspices of the ISO working group fo Document Description and Processing Languages It laid out the fundamental rules for describing the parts of a formatted document that inspired later efforts including XSL and CSS Concepts such as bounding boxes and font properties are painstakingly defined here If you look at a DSSSL scri
118. lt head gt lt body gt lt page content goes here lt body gt entm lt xsl template gt Let us add a section that Summarizes income activity The section header wrapped inside anh3 element is generated using new text withtext not present in the document and the dates from the first and last transactions using value of After the header all the income transactions are listed in the order they appear with apply templates The rule now looks like this downloaded from lib ommolketab ir downloaded from lib ommolketab ir lt xsl template match checkbook gt SPEI oS lt head gt lt body gt lt l income nrormatlon gt ens xsl text Income from xsl text lt xsl value of select 2 child 1 date xsl text until xsl text xslivalu of se lecte child last date xsl text xsl text P dus xsl apply templates select deposit lt 7 body gt IET xsl template After that we will add a section to describe the deductions from the checking account It would be nice to sort this list of transactions from highest to lowest so let s use thesort element The rule is now lt xsl template match checkbook gt emt lt head gt Douay Il Income 2ntormation gt cn xsl text Income from xsl text lt xsl value of select child 1 date gt xslttext until xsl texr lt xsl value of select 2 child last date xslrtext
119. many languages each specific to its data Users can choose element names and decide how they should be arranged in a document The result will better labeling of data richer formatting possibilities and enhanced searching capability A document should be unambiguous A document should be marked up in such a way that there is only one way to interpret the names order and hierarchy of the elements Consider this example from old style HTML SOLmL body p Here is a paragraph p And here is another body downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt html gt Before XML this was acceptable markup Every browser knows that the beginning of a lt p gt signals the end of an open p element preceding it as well as the beginning of a newp element This prior knowledge about a markup language is something we don t have in XML where the number of possible elements is infinite Therefore it s an ambiguous situation Look at this example does the first element contain the other or are they adjacent lt flooby gt an element lt flooby gt another element You can t possibly know and neither can an XML parser It could guess but it might guess incorrectly That s why XML rules about syntax are so strict It reduces errors by making it more obvious when a document has mis coded markup It also reduces the complexity of software since programs won t have to make an educated guess or try to fix
120. name postalcode gt lt xs simpleType gt xs restriction base string gt xs pattern value 0 9 3 A Z 3 gt lt xs restriction gt lt xs simpleType gt downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir xs element lt structure containing data for one resident of the household lt xs element name person gt lt xs complexType gt aie cea a Mlle lt xs element ref name gt lt xs element ref age gt lt xs element ref gender gt lt xs all gt lt xs attribute ref employed gt lt xs attribute ref pid gt lt xs complexType gt lt xs element gt lt Employment status fulltime parttime or none gt lt xs attribute name employed gt lt xs simpleType gt xs restriction base string gt lt xs enumeration value fulltime gt xs enumeration value parttime gt lt xs enumeration value none gt lt xs restriction gt lt xs simpleType gt lt xs attribute gt lt Number identifying the person 1 999999 gt xs attribute name pid gt lt xs simpleType gt xs restriction base integer gt exoomamninclosive e value 1 7 gt lt xsi maxInclusive value 999999 gt a7 XS pestrloctron lt xs simpleType gt lt xs attribute gt amp l Age 0 200 gt lt xs element name age gt lt xs complexType gt xcslrestrlocron b ce inLeger xstmmmminelussve value xs maxlInclusiv
121. namespaces which allow you to import vocabularies from anywhere Granted there are good reasons to want to limit the kinds of elements used more efficient validation and aine illegal elements from appearing But there s no way to turn this feature off if you don t want it 24 5 There is a complex parameter entity hack for creating DTDs that can cope with namespaces Although the W3C has used it for both XHTML and SVG modularization it s both fragile and a huge readability problem To address problems like these a new validation system was invented calledschema Like DTDs schemas contain rules that all must be satisfied for a document to be considered valid Unlike DTDs however schemas are not built into the XML specification They are an add on technology that you can use provided you have access to parsers that will support it There are several competing kinds of schema The one that is sanctioned by the W3C is called XML Schema Another proposal called RELAX NG adds capabilities not found in XML Schema such as regular expression matching in character data Yet another popular alternative is Schematron We ll focus on the W3C variety in this section and visit alternatives in later sections XML Schemas are themselves XML documents That s a nice convenience allowing you to check well formedness and validity when you make modifications to a schema It s more verbose than a DTD but still pretty readable and vastly more flexible Fr
122. no more than eight characters lt element name username xmlns http relaxng org ns structure 1 0 data type string gt lt param name maxLength gt 8 lt param gt lt data gt lt element gt 4 4 3 Attributes Attributes are declared much the same way as elements In this example we add adate attribute to the report element downloaded from lib ommolketab ir downloaded from lib ommolketab ir lt element name report xmlns http relaxng org ns structure 1 0 lt attribute name date gt lt text gt lt attribute lt element name title gt lt text gt lt element gt lt element name body gt lt text gt lt element gt lt element gt Unlike elements the order of attributes is not significant In this next example the attributes for any alert element can appear in any order even though we are not using achoice element lt element name alert xmlns http relaxng org ns structure 1 0 lt attribute name priority gt lt value gt emergency lt value gt lt value gt important lt value gt lt value gt warning lt value gt lt value gt notification lt value gt lt attribute gt lt attribute name 2 icon lt value gt bomb lt value gt lt value gt exclamation mark lt value gt lt value gt frown face lt value gt attrib te element name body gt text lt element gt lt element gt Element and attribute declarations are interchangeable H
123. of dark characters to add separation When you quickly scroll through the file you will find it is much easier to navigate Comments downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Use comments liberally they are signposts in a wilderness of declarations First place a comment at the top of each file that explains the purpose of the DTD or module gives the version number and provides contact information If it is a customized frontend to a public DTD be sure to mention the original that it is based on give credit to the authors and explain the changes that you made Next label each section and subsection of the DTD Anywhere a comment might help to clarify the use of the DTD or explain your decisions add one As you modify the DTD add new comments describing your changes Comments are part of documentation and unclear or outdated documentation can be worse than useless Version tracking As with software your DTD is likely to be updated as your requirements change You should keep track of versions by numbering them to avoid confusion it s important to change the version number when you make a change to the document By convention the first complete public release is 1 0 After that small changes earn decimal increments 1 1 1 2 etc Major changes increment by whole numbers 2 0 3 0 etc Document the changes from version to version Revision control systems are available to automate this process
124. of space defined by four widths calledmargins Figure 5 10 The CSS box model A block s boundaries hold content while separating the block from sibling blocks Any background image or color is confined to the area within the boundary while text and nested boxes are confined to an even smaller area the rectangle determined by the boundary minus padding If the boundary i not displayed the padding is often set to zero Margins demarcate a rectangular region outside the box that keeps other boxes away downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 5 4 4 1 Margins A common way to adjust space around an element is to set its margins A margin is the distance between the bounding box of an element and that of any neighboring or containing element The four sides of a box have their own margin property margin left margin right margin top and margin bottom The value can be a length or a percentage of the containing element s width The margin property is shorthand for defining all four sides of the margin Its value is a space separated list containing between one and four lengths or percentages If only one value is specified that value applies to all four sides If there are two values the first sets the top and bottom margins and the second sets the left and right margins If there are three values the first assigns the top margin the second assigns both the left and right margins and the third assign
125. of the part 5 he instructions element is a numbered list so output the container element for that 6 For each step element output an item for the instructions list The stylesheet in Example 7 2 follows the same structure as these English rules with a template for each Example 7 2 XSLT stylesheet for the instruction guide xsl stylesheet xmlns xsl http www w3 org 1999 XSL Transform version 1 0 xsl output method xml encoding ISO 8859 1 gt 1 Handle the document element set up the HTML page gt lt xsl template match manual gt lt html gt lt head gt lt title gt Instructions Guide lt title gt lt head gt body lt hi gt Instructions Guide lt hl gt xsl apply templates lt body gt lt html gt lt xsl template gt lt Create a parts list gt lt xsl template match parts list gt ehzcpPertees a2 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Seul xsl apply templates ROS lt xsl template gt lt One use of the part element item in a list gt lt xsl template match part label gt SL lt xsl value of select label gt sis lt dd gt lt xsl apply templates gt dd lt xsl template gt lt another use of the lt part gt element generate part name lt xsl template match part ref gt lt xsl variable name label select ref gt lt xsl value of select part l
126. of the spacing and padding properties as well These details usually settled in a stylesheet XML doesn t or shouldn t tangle with presentational aspects any more t it has to 3 2 4 Metadata Metadata is information about the document that is not part of the flow It s useful to keep with the rest the document but it s not formatted or else it s formatted in a special way such as on a title page Examples include author name copyright date publisher revision history ISBN and catalog number In XHTML for example a whole part of the document thehead element is reserved to hold metadata I the title descriptive terms for search engines links to stylesheets and so on In DocBook metadata cal associated with individual sections which is useful to associate authors with individual articles for exam 3 2 5 Linked Objects The last bunch of oddball elements often found in narrative documents can be classified aslinked objects These are elements that act as bookmarks in a document The way you might stick a paperclip on a pag bend over the corner to mark the page is how they work First there is the cross reference an element that refers to a section or object somewhere else in the document When formatted it may be replaced with generated text such as the section number or title the referred object It may be turned into a hyperlink which when clicked transports the user directly tc object downloaded from lib ommolketab ir
127. of well downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir formedness In other words any branch you pluck out of a document could be run through an XML parser which wouldn t know or care that it wasn t a complete document But a grove group of adjacent trees is not well formed XML n order to be well formed all of the elements must be contained inside just one the document element To describe elements in relation to one another we use genealogical terms Imagine that elements are like single celled organisms reproducing asexually You can think of an element as the parent of the nodes it contains known as its children So the root of any tree is the progenitor of a whole family with numerous descendants Likewise a node may have ancestors and siblings Siblings to the left appearing earlier in the document arepreceding siblings while those to the right are following siblings These relationships are illustrated in Figure 2 16 Figure 2 16 Genealogical concepts ancestors sibling descendants The tree model of XML is also important because it represents the way XML is usually stored in computer memory Each element and region of text is packaged in a cell with pointers to children an parents and has an object oriented interface with which to manipulate data This system is convenient for developers because actions like moving document parts around and searchingfor text are easier and more
128. ommolkcefab ir the current node whereas apply templates operates on whatever nodes you select the child nodes by default You can include or import any number of stylesheets which lets you mix and match different vocabularies for transformation You may have one set for generic document content another for handling tables yet another for handling sidebars and so on The order of inclusion is used to break ties between conflicting rules from different sets earlier imports override later ones Here s how you can import several stylesheets into your own xsl stylesheet version 1 0 mninsixslbe RELpi www wSorg l99D eo rane orm xsl import href basic style xsl xsl import href table styles xsl xsl import href chem formulae xsl 7 6 10 Modes Sometimes you want totreat nodes differently depending on where they are used in the document For example you may want footnotes in tables to be alphabetized instead of numbered XSLT provides special rule modifiers calledmodes to accomplish this To set up a mode simply add amode attribute set to a particular label to the affected template and template calling elements The mode label can be anything you want as long as it s unique among mode labels The following example shows how to do this lt xsl template match footnote gt lt xsl variable name fnum select count preceding footnote ancestor chapter 1 gt lt a xsl attribute name href lt xs
129. ommolketab ir downloaded from fib ommolkcefab ir Example 3 11 RSS describing a web site lt xml version 1 0 encoding ISO 8859 1 standalone yes gt lt rss version 2 0 gt lt channel gt lt title gt Lifestyles of the Foolhardy lt title gt lt link gt http www foolhardy org lt link gt lt description gt Incredibly bold or just plain stupid Tips and tricks for folks who just don t have time to think about safety lt description gt lt language gt en us lt language gt lt copyright gt Copyright 2002 Liv Dangerously lt copyright gt lt lastBuildDate gt Fri 20 Sep 2002 11 05 02 GMT lt lastBuildDate gt lt managingEditor gt liv foolhardy org Liv Dangerously lt managingEditor gt lt item gt lt title gt Using a Hair Dryer in the Bathtub lt title gt lt pubDate gt Fri 20 Sep 2002 11 05 02 GMT lt pubDate gt lt link gt http www foolhardy org art tub html lt link gt lt description gt Don t wait till bathtime is over to dry your hair Save time and do both at once lt description gt lt item gt lt item gt lt description gt sounds of someone falling down the stairs a brave soul proving that rollerskates aren t just for flat surfaces lt description gt lt pubDate gt Fri 20 Sep 2002 10 28 19 GMT lt pubDate gt lt enclosure url http www foolhardy org sounds stairs mp3 length 44456 type audio mpeg gt lt item gt lt channel gt cCIpes The first thing inside the d
130. paramere entity ee lt ENTITY author Erik Ray gt definition to the parsing environment processing Feed a special instruction to a particular type of print formatter force instruction software linebreak gt comment Insert an annotation that will be ignored by the zi Whereis where d tere ore XML processor Create a section of character data that should not I CDATA section be parsed preserving any special characters CDATA LAmpersands galore inside it amp amp amp amp amp amp 7 entity Command the parser to insert some text stored amp company name reference elsewhere Elements are the most common XML object type They break up the document into smaller and smaller cells nesting inside one another like boxes Figure 2 1 shows the document in Chapter 1 partitioned into separate elements Each of these pieces has its own properties and role in a document so we want to divide them up for separate processing Figure 2 1 Telegram with element boundaries visible downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir xml version 1 0 gt telegram ori important gt tooSarah Bellumc to from gt Colonel Timeslip lt from subject gt Robot sitting instructionsc subject graphic fileref Tigs me jpgp messape gt Thanks for watching my robot pal cname Zonky name while I m away He needs to be recharged cemphasis twice a day emphasis and if he sta
131. perhaps to declare your own version of screeninfo Turning off the declarations for an element in the imported file avoids warnings from your parser about redundant declarations Notice that there are parameter entities tc assign various kinds of content and attribute definitions such as common attrib There are also hooks for inserting attributes of your own such as 1ocal screenshot attrib Skillful use of conditional sections can make a DTD extremely flexible although it may become harde to read You should use them sparingly in your personal DTDs and try to design them to fit your needs from the beginning Later if the DTD becomes a public resource it will make sense to add conditional sections to allow end user customization 4 2 4 6 Using the internal subset Recall from Section 4 2 2 earlier in this chapter that the internal subset is the part of an XML document that can contain entity declarations Actually it s more powerful than that you can put any declarations that would appear in a DTD into the internal subset The only things that are restricted are conditional sections can t use them and parameter entities they can hold only complete declarations not fragments This is useful for overriding or turning on or off parts of the DTD Here s the general form lt DOCTYPE root element URI declarations When a parser reads the DTD it reads the internal subset first then the external subset This is important because th
132. returns the indent of the item body Similarly you can set the parameterstart indent in list item body to body start a function that returns the indent of the start of the body of the list item These values are calculated based on the propertyprovisional distance between starts You don t have to use them but without them you run the risk of the label overlapping the body or not being able to fit into the space allotted to it The following part of the stylesheet creates a numbered list lt xsl template match orderedlist gt Snore biloci margin left 5mm space before 5mm space after 5mm provisional distance between starts 15mm provisional label separation 5mm downloaded from lib ommolketab ir downloaded from lib ommolketab ir xsl apply templates e forlleteblok lt xsl template gt lt xsl template match orderedlist listitem gt lt fo list item gt lt fo list item label start indent 5mm end indent label end gt LPotD Lock xsl number format 1 gt 105 block fo list item label fo list item body start indent body start ero plocmx xsl apply templates amp EJTGSDIDGE eFforzlist ltem bDodv fo list item lt xsl template gt To format a bulleted list simply replace the number with some other character lt xsl template match itemizedlist gt rot liet pico margin left 5mm space before 5mm space after 5mm provisional distance between
133. same 1 diff is a program in Unix that compares two text files and reports when any two lines are different Even if one character is out of place it will find and report that fact To show these nodes in their natural habitat let s look at an example The following document contains all the node types and Figure 6 1 shows how it looks as a tree lt l Degelqcorousi gt sandwich xmlns http www food org ns gt ingredient type grape gt jelly lt ingredient gt lt ingredient gt lt knife spread thickly gt peanut butter lt ingredient gt lt ingredient gt bread lt rye bread preferably gt lt ingredient gt lt sandwich gt Figure 6 1 Tree view showing all kinds of nodes downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir root node sandwich 6 1 2 Trees and Subtrees If you cut off a branch from a willow tree and plant it in the ground chances are good it will sprout into a tree of its own Similarly in XML any node in the tree can be thought of as a tree its own right It doesn t have a root node so that part of the analogy breaks down but everything else is there the node is like a document element it has descendants and it preserves the tree structure ir a sort of fractal way A tree fashioned from an arbitrary node is called asubtree For example consider this XML document lt xml version 1 0 gt lt manual type assembly id model rocket gt
134. schemas are best prepared to handle this level Data typing is often useful especially in data style documents but not widely supported Testing integrity is less common and somewhat problematic to define Business rules are often checked by applications downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 4 1 2 A History of Schema Languages There are many different kinds of XML schemas each with its own strengths and weaknesses 4 1 2 1 DTD The oldest and most widely supported schema language is the Document Type Definition DTD Borrowed from SGML a simplified DTD was included in the XML Core recommendation Though a DTD isn t necessary to read and process an XML document it can be a useful component for a document providing the means to define macro like entities and other conveniences DTDs were the first widely used method to formally define languages like HTML 4 1 2 2 W3C XML Schema As soon as XML hit the streets developers began to clamor for an alternative to DTDs DTDs don t support namespaces which appeared after the XML 1 0 specification They also have very weak data typing being mostly markup focused The W3C formed a working group for XML Schema and began to receive proposals for what would later become their W3C XML Schema recommendation Following are some of the proposals made by various groups XML Data Submitted by Arbortext DataChannel Inso Corporation Microsoft and the U
135. selected element See alsoCSS rule stylesheet proposed recommendation A specification that has been evaluated by the public and is deemed by a standards body to warrant a full recommendation pseudo class A CSS selector that specifies a certain instance of an element instead of all occurrences of the element For example the first paragraph of each section can be grouped as a pseudo class See also CSS rule selector PUBLIC identifier The identifier in the document prolog that gives the name of a DTD or external entity Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Q qualified element name An element identified in a specific namespace A qualified element name uses a namespace prefix in the tag name See also element namespace namespace prefix Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB R recommendation In the standards process a recommendation is a specification that has achieved majority approval of its working group and its host organization and is released for outside evaluation reference To refer to or reference something is to indicate a relationship between the current context anc an outside resource Usually the intent is to import a value into a collection of data For example an entity reference is a fragment of text telling an XML parser to insert the value of an en
136. serif Note that font names with spaces must be quoted Capitalization is not necessary The first option offers the most alternatives but by including Palisades it risks diminishing the appearance of the document The second is much shorter and says If can t have Palatino then just use Times New Roman The third ambitiously strives for BT Humanist 521 but will settle for downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir common Palatino All of these include the serif generic as a last resort letting the system pick any serif font if all else fails 5 4 5 2 Font size The size of a font is determined by the font size property The value can be given in absolute units points usually or relative units percentages or ems of the parent s font You can also use semi absolute keywords xx small x small small medium large x large xx large The CSS specification recommends that CSS processors display each size 1 2 times larger than the previous one so that xx large would be 3 6 times the size of xx smal11 but the actual sizes are left to user preference This provides a nice way to specify sizes relative to your audience s comfort levels at the cost of losing absolute precision Figure 5 13 shows how these different font sizes might look Figure 5 13 Font sizes Relative keywords are also available larger smaller These move the size up or down by a size factor 5 4 5 3 Line
137. set A collection of letters numbers and symbols representing a language or set of languages mapped to specified numbers that can be understood by computer programs See also character encoding downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir comment Specially marked text in the document source that is not interpreted by the parser XML comments are surrounded by lt and delimiters Everything inside a comment is ignored by the parser including tagged elements Comments can provide additional information about a document s markup and content and are a useful way to remove content from a document s output without fully deleting it See alsomarkup container element An element that contains character data or other elements is called a container It is a root to its own subtree in the document See alsocontent content model element content Anything in a document that is not markup Take away the tags comments and processing instructions and what s left is content or character data Markup allows content to be repurposed many ways See also container element content model content model The technical specification of a DTD that describes an element s contents The content model specifies which kinds of elements and data can occur within an element how many can occur and how they are ordered See also element content CSS Cascading Style Sheets This specification provides a stan
138. size as the desired font 5 4 5 4 Font style and weight Font families contain variants that allow an author to add emphasis or meaning to parts of the text There are two kinds of variants font style italic oblique and font weight light bold The font style property has four possible settings normal The traditional upright version of the font deese An italic version of the font if available or the oblique version oblique The oblique version if available or the normal font with a slight slant effect inherit Whatever setting the parent element has The CSS specification is not clear on the effect of italic on languages without a tradition of italics as result it is probably best to specify an alternative typeface for other languages em font style italic em lang ja font family font style normal The font weight property controls how bold or light a font is The following keyword values are defined downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Lagi A light and airy version of the font if available Otherwise the user s system may generate one automatically norma The standard variant of the font bola A darker heavier version of the font if available Otherwise the user s system may generate one automatically There are also relative keywords which decrease or increase the weight with respect to the parent s property lighter Decrea
139. some space in places to make it more readable Example 8 4 Formatting object tree of the TEI document lt xml version 1 0 gt fo root xmlns fos http www w3 org 1999 XSL Format rto layout master set lt fo simple page master master name the only page type page height l11lin page width 8 51in margin top 2 1in margin bottom lin margin left 1 21in margin right 1 21in gt fo region body margin top 20mm fo region before extent 0 3in gt lt fo simple page master gt fo layout master set fo page sequence master reference the only page type fo static content flow name xsl region before lt fo block font family geneva sans serif font size 8pt text align left border bottom solid lpt black gt ohakespeare s Sonnets XVIII aj EO DIOGk gt lt fo static content gt lt fo flow flow name xsl region body font family didot serif font size l pt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt fo block font weight bold space before 2mm space after 4mm gt shall I Compare Thee to a Summer s Day Q Toso lock gt lt fo block font style italic space after 4mm gt by William Shakespeare lt fOtblock gt lt LO DLOCK gt SIOSDILOURS shall I compare thee to a summer s day xd siete lke ale lt fo block start indent 5mm gt Thou art more lovely and more temperate eTOo sDlogks Ot LOCK Rough winds do shake the darling buds of
140. support for CSS now Internet Explorer whicl used to be the leader has inexplicably remained stuck for over a year and Microsoft has suggested its development as a standalone application is complete Sure CSS is rich and featured but it shouldn t be that difficult to implement think the open source movement offers the most hope because there will always be an opportunity for some hacker fed up with an unimplemented option to go in and get it working whereas with corporations we have to wait until the marketing department deems it a high enough priority to put it on the schedule Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 5 2 CSS Basics While CSS is a field of endeavor all its own we ll get started with some foundations 5 2 1 The CSS Specification Cascading Style Sheets CSS is arecommendation developed by the World Wide Web Consortium W3C It originated in 1994 when Hakon Wium Lee working at CERN the birthplace of HTML published a paper titled Cascading HTML Style Sheets It was a bold move at the right time By then the Web was four years old and growing quickly yet there was still no consensus for a standard style description language The architects of HTML knew that the language was in danger of becoming a style description language if something like CSS wasn t adopted soon The goal was to create a simple yet expressive language that could combine sty
141. text gt aor lt xsl template gt Finally here s the rule for deposit lt xsl template match deposit gt dep lt xsl value of select position gt lt xsl text gt On lt xsl text gt lt xsl value of select date gt lt xsl text gt lt xsl text gt LCE D gt lt xsl text gt lt xsl text gt lt xsl value of select amount gt oder a amor lt xsl text gt was deposited into your account by lt xsl text gt lt i gt lt xsl value of select payor gt lt i gt lt xsl text gt lt xsl text gt lt p gt lt xsl template gt Putting it all together in one stylesheet we get the listing inExample 7 4 Example 7 4 Checkbook transformation stylesheet lt xml version 1 0 gt eee A simple transformation stylesheet to get information out of a checkbook xsl stylesheet xmlns xsl http www w3 org 1999 XSL Transform version 1 0 gt lt xsl template match checkbook gt Gl gma diel lt head gt lt body gt downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir enm xsl text Income from xsl text lt xsl value of select child 1 date gt lt xsl text gt until lt xsl text gt lt xsl value of selecr ohlildsi llasti l date lt xsl text gt lt xsl text gt e gs xsl apply templates select deposit en lt xsl text gt Expenditures from xsl text exelisvalue or selecte childr l1 date lt xslitext
142. the structure and contents of a document The Core also contains specialized interfaces dedicated to XML SAX downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The Simple API for XML is a free API for event based XML parsing saxproject org Status SAX was collaboratively developed by the XML DEV mailing list hosted by OASIS The current release is SAX 2 0 dated May 2000 SAX is maintained by David Brownell at http www saxproject org Description SAX2 Is an event based API SAX2 introduces configurable features and properties and adds support for XML Namespaces It also includes adapters that allow it to interoperate with SAX1 parsers and applications Canonical XML A standard representation of XML documents for signatures W3C I ETC Status Canonical XML was collaboratively developed by the W3C and IETF There are two current Recommendations the March 2001 Canonical XML 1 0 athttp www w3 org TR xml cl4n and the July 2002 Exclusive XML Canonicalization Version 1 0 athttp www w3 org TR xml exc cl14n Description Canonical XML is designed to remove all the syntactical variations of XML documents and produce a single representation which can be used reliably for tasks like checksums and signatures XML Signature A standard representation of XML documents for signatures W3C I ETC Status downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XM
143. the MathML document used to generate this figure Example 3 9 Presentation encoding in MathML lt xml version 1 0 gt math xmins http www w3 org 1998 Math MathML mn 1 mn mo mo lt m rac gt lt mrow gt lt mn gt 1 lt mn gt lt mrow gt lt mrow gt lt mn gt 1 lt mn gt lt mo gt lt mo gt lt mfrac gt lt mrow gt lt mn gt 1 lt mn gt lt mrow gt lt mrow gt lt mn gt 1 lt mn gt lt mo gt lt mo gt lt mfrac gt lt mrow gt lt mn gt 1 lt mn gt lt mrow gt lt mrow gt lt mi gt x lt mi gt lt mrow gt lt mfrac gt lt mrow gt lt mfrac gt lt mrow gt lt mirac gt lt math gt mfrac as you may have guessed sets up a fraction It contains two elements calledmrow one each for the top and bottom Notice how the denominator can itself contain a fraction Take this recursively as far as you wish and it s perfectly legal in MathML At the atomic level of expression are numbers variables and operators which are marked up with the simple elementsmn number mi identifier and mo operator downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Conceptual encoding also known as content encoding is the name given for the other mode of MathML It resembles functional programming notably LISP in that every sum fraction and produci is represented as an operator followed by arguments all wrapped up in anapply element Example 3 10 shows how the equation 2a
144. the attribute name with a dot and a component name For example Space before minimum 2pt If you use space before 3pt forgoing the components it will be equivalent to this Space before minimum 3pt Space before optimum 3pt Space before maximum 3pt Let s illustrate these spacing techniques in an example We will use the following source document article title Batten Down the Hatches title lt para gt People who download copyrighted materials from the Internet should have their computers destroyed said Senator Orrin Hatch R Utah in a recent statement lt para gt lt para gt In a sweet twist of irony Wired News reported that the Senator s own web site was guilty of using unlicensed software to generate menus lt para gt article Here is an XSLT stylesheet to format this document with space around blocks lt xml version 1 0 gt xsl stylesheet xmlns xsl http www w3 org 1999 XSL Transform xmlns fo http www w3 org 1999 XSL Format version 1 0 gt xsl output method 2 xml 1 Set up the master page and apply a flow to it gt lt xsl template match gt EIOTUTOOL rto layout master set lt fo simple page master downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir master name the only page type page height 6in page width 3in margin top U Sin margin bortome 0 51n margin left 0 5in margin right 0 5in gt fo
145. the document called an area tree This in memory representation of the output is composed of overlapping and nested canvases calledareas Each area is a region of the document with a set oftraits that describe how its the content should be rendered An area can be as large as e sidebar or as small as a single glyph Finally the formatter enters its rendering phase The area tree translates directly into some output format such as PDF or troff that exactly conforms to the original specifications At last you see something emerge from the black box a tangible product that hopefully looks the way you wanted it to The normal user will not need to know how the phases from objectification to rendering actually work She has put down her constraints in the XSLT stylesheet and the rest is automatic The actual work that takes place inside the formatter is more of interest to developers who write and maintain such software 8 1 2 Formatting Objects Formatting objects come in a variety of types representing what you can do typographically in a document There are FOs for blocks and inlines section containers and individual character containers page and style settings The complete set of formatting objects is the vocabulary for formatting abstractions possible in XSL Each FO represents a semantic specification for a particular part of a document It has default properties that you can override as necessary These defaults depend on the context such
146. the element name may not be known at the time you write the stylesheet It has to be generated dynamically This would be an application ofelement The name attribute sets the element type For example exsltitemplate match shape xsl element name type gt lt xsl value of select gt lt xsl element gt lt xsl template gt If this template is applied to an elementsnape with attribute type circle it would create an element of type circle 7 6 4 2 Attributes and attribute sets have already shown you how to create attributes with attribute As with element generation you can derive the attribute name and value on the fly Note however that anattribute directive must come before any other content It is an error to try to create an attribute after an element or text node To apply a single set of attributes to many different elements you can useattribute set First define the set like this xsl attribute set name common atts lt xsliattribute namese id lt xsl value of select generate id gt xsl attribute xsl attribute name class gt lt xsl text gt shape lt xsl text gt xsl attribute xsl attribute set This creates a set of two attributes id with a unique identifier value andciass shape The set can be accessed from any element through its name common atts Use the attribute use attribute sets to refer to the attribute set you defined lt xsl template matcocu guot
147. the location of a node easily in simple shorthand Like real trees you can break a piece off and treat it like a smaller tree Most important you have all the information in one place for as long as you need it This persistence is the key reason for using trees If you can live with the overhead of memory and time to construct the tree then you will enjoy luxuries like being able to pull data from anywhere in the document at any point of the processing With streams you are forced to work with events as they arrive perhaps storing bits of data for later use Tree processing is usually object oriented The data structure representing the document is composed of objects whose methods allow you to traverse in different directions pull out data or modify values DOM as we will see later in the chapter is a standard that defines the interfaces of objects used to built document trees Encapsulating XML data in objects is as naturalas using markup with as many benefits Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 4 Pull Parsing Tim Bray lead editor of XML 1 0 calls pull parsing the way to go in the future Like event based parsing it s fast memory efficient streamable and read only The difference is in how the application and parser interact SAX implements what we callpush parsing The parser pushes events at the program requiring it to react The parser doesn t
148. this node are candidates for processing and the XSLT processor must select one Second the template contributes a priority value to help the processor decide which among eligible templates is the best to use The template that matches the current node with the highest import precedence or highest priority is the one that will be used to process it Different factors contribute to this priority A template with more specific information will overrule one that is more generic For example one template may match all elements with the XPath expression Another may match a specific element while a third matches that element and further requires an attribute Alternatively a template can simply state its precedence to the processor using apriority attribute This is useful when you want to force a template to be used where otherwise it would be overlooked The third role of a template is to specify the structure of the result tree The template s content actually contains the elements and character data to be output in the result tree So it is often possible to see at a glance how the result tree will look XSLT elements interspersed throughout thi content direct the processing to other templates This model for scripting a transformation has strong benefits Templates are usually compact piece of code that are easy to read and manage like functions in a programming language Thematch and priority attributes show exactly when each template is
149. top to bottom Ir tb European languages are in this category e Right to left top to bottom rl tb For example Arabic and Hebrew e Top to bottom right to left tb rl Chinese and Japanese are examples Figure 8 4 is an example of Chinese text The inline progression is top to bottom and the block progression is right to left Figure 8 4 Chinese text showing block and inline progression directions In contrast Figure 8 5 shows Italian text which is left to right and top to bottom Figure 8 5 Italian text showing block and inline progression directions downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Start Ha detto venite qui spesso Ha riposte ora che siete gui lo pensa che mo venissi mai ancora qui Quella era l estremita Block progression direction You can set the writing mode in any flow block or inline formatting object with the propertywriting mode For example here is how you might write a template for an elementhebrew phrase lt xsl template match hebrew phrase gt fo inline writing mode rltb gt xsl apply templates efTrosdspnlicfe lt xsl template gt You can embed this inline in an English paragraph and when rendered the paragraph will appear Irtb except for the inline which will be rl tb 8 3 2 Dimensions Since XSL borrows heavily from CSS it also happens to use the same methods of defining dimensions You can express them in r
150. version labeled with a different language A web browser could be set to ignore all but a particular language filtering the document so that it displays only what the reader wants Or if you re writing a book that includes text in different languages you could configure your spellchecker to use a different dictionary for each version The attribute s value is a string containing a two letter language code like so xml lang en The code en stands for English The language codes standardized in SO 639 are case insensitive so there are 262 676 possible codes Three letter codes are also specified but XML only recognizes two letter codes this could be a problem in a world with thousands of different languages dialects and subdialects Fortunately we can also specify a language variant using aqualifier like this xml lang en US This refers to the American variant of English By convention we usually write the language code in lowercase and the qualifier in uppercase Now we can separate different kinds of English like so para xml lang en US gt Please consult the program lt para gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir para xml lang en GB Please consult the programme lt para gt If for some reason you need to define your own language you can do so by using the language code x Some examples could include x pascal x java x martian and x babytalk 9 3 2 Language S
151. while the rapid changes in the industry ensure that we could never hope to keep up with the latest XML software Nevertheless the information presented here will give you a decent starting point for jumping in any direction you want to go with XML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB What s Inside The book is organized into the following chapters Chapter 1 is an overview of XML and some of its common uses It s a springboard to the rest of the book introducing the main concepts that will be explained in detail in following chapters Chapter 2 describes the basic syntax of XML laying the foundation for understanding XML applications and technologies Chapter 3 delves into the concepts of data modeling showing how to encode information with XML from simple software preferences to complex narrative documents Chapter 4 shows how to use DTDs and various types of schemas to describe your document structures and validate documents against those descriptions Chapter 5 explores Cascading Style Sheets CSS a technology for presenting your XML documents in web browsers Chapter 6 explains XPath a vocabulary for addressing parts of XML documents that is useful both fo transformations and programming as well as its extensions into XPointer Chapter 7 applies XPath demonstrating how to use Extensible Stylesheet Language Transformations XSLT to transform
152. xs QName Contains a namespace qualified name Contains a decimal number of arbitrary precision Processors must support a minimum of 18 digits 3 252333 1 01 and 20 are all acceptable values xs integer Contains an tiM UMMEMIEMEE 3 number like O 35 or 1433322 xs float Contains a 32 bit IEEE 754 Contains a 32 bit IEEE 754 floating point number point number ae gue uy Behave the same as the ID IDREF IDREFS in DTDs xS IDREF xs boolean Contains a true or false value expressed as true or false or 1 or O be ped ue Contains a time in ISO 8601 format HH MM SS Timezone like 21 55 00 xetcdeocvmal 06 00 xs date Contains a date in ISO 8601 format CCYY MM DD like 2004 12 30 Contains a date time combination in ISO 8601 format CCYY MM DDTHH MM SS Timezone like 2004 12 30T21 55 00 06 00 Most elements are not simple however They can contain elements attributes and character data with specialized formats So schemas also contain complex element definitions Here s how you coulc define the date element lt xs element name date gt lt xs complexType gt ote lt xs element ref year gt lt xs element ref month gt lt xs element ref day gt 2otali gt lt xs complexType gt lt xs element gt lt xs element name year type xs integer gt lt xs element name month type xs integer gt lt xs element name day t
153. xsl template match document gt lt regular page markup here gt xsl call template name 2 copyright info 1 generate a page number gt lt xsl template gt lt xsl template name copyright info gt lt p This is some text the lawyers make us write It appears at the bottom downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir of every single document ad nauseum Blah blah all rights reserved blah blah blah under penalty of eating yogurt blah blah lt p gt lt xsl template gt The first template calls the second named template Processing jumps over to the named template then returns to where it left off in the first template The context node set does not change in this jump So even in the named template you could check what is the current node withself node and it would be exactly the same Here is another example This named template generates a menu of navigation links for an HTML page lt xsl template name navbar gt lt div class navbar gt lt xsl text gt Current document lt xsl text gt lt xsl value of select title gt dotar de lt a hrer rndex htm Homee a lt a href help htm gt Help lt a gt lt a href toc htm gt Contents lt a gt lt div gt lt xsl template gt Before the links placed two lines to print the current document s title demonstrating that the current node is the same as it was in the rule that invoked the na
154. y y y y y XML Spy yes yes yes yes yes The features of structure and validity checking can be taken too far All XML editors will warn you when structural errors or improper element placement validity errors A few like Corel s XMetal prevent yot temporarily making the document invalid A user who is cutting and pasting sections around may tempo to break the validity rules The editor rejects this forcing the user to stop and figure out what is going v rather awkward to have your creativity interrupted that way When choosing an editor you ll have to we benefits of enforced structure against the interruptions in the creative process A high quality XML authoring environment is configurable If you have designed a document type you s able to customize the editor to enforce the structure check validity and present a selection of valid eler choose from You should be able to create macros to automate frequent editing steps and map keys on to these macros The interface should be ergonomic and convenient providing keyboard shortcuts inste mouse clicks for every task The authoring tool should let you define your own display properties wheth large type with colors or small type with tags displayed Configurability is sometimes at odds with another important feature ease of maintenance Having an ec formats content nicely for example making titles large and bold means that someone must write and stylesheet Some editors have a reasonably g
155. you may nat be able to use TU literal and IDREF attributes for linking If you use names like ume SGML CCHAPTER CV5S 1 1 Fill Figure 1 6 Morphon Technologies XMLEditor downloaded from fib ommolkcefab ir Arbortext s Epic Editor is a very polished editor that can be integrated with digital asset management sy high end compositing systems A screenshot is shown in Figure 1 7 Like Morphon s editor it uses CSS 1 the text displayed There are add ons to extend functionality such as multiple author collaboration impc and exporting to Microsoft Word formatting for print using a highly detailed stylesheet language called powerful scripting language The quality of output using FOSI is good enough for printing books and yo how it will look on screen At around 700 a license you pay more but you get your money s worth wit downloaded from lib ommolketab ir File Edit View Tools Layout Help r7 ats aug m en Alla aa l l ll ml 3 x E E am ik B x uU D 2 D CLLIILL S E ______ ic ae le ed MMM L3 para A ii appa xmli readme xml procedure b jJ section Nes Y E section Nest titie V section Pretty 3 title Deep Y I section 3 tithe Y C section title e l LM para The
156. 0 XML parsing downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The next level of parsing occurs when the tags and symbols have been identified and now affect the inte checking mechanisms of the parser The well formedness rules now direct the parser in how to handle t example an element start tag tells the parser to store the name of the element in a memory structure c stack When an element end tag comes along it s checked against the name in the stack If they match element is popped out of the stack and parsing resumes Otherwise something must have gone wrong parser needs to report the error One kind of symbol called anentity reference is a placeholder for content from another source It may character or it could be a huge file The parser looks up the source and pops it into the document for pe there are entity references inside that new piece of content they have to be resolved too XML can com sources including files databases program output and places online Above this level is the structure checking also calledvalidation This is optional and not all parsers can is a very useful capability Say for example you are writing a book in XML and you want to make sure 1 section has a title If the DTD requires a title element at the beginning of the section element then the expect to find it in the document If a section start tag is followed by something other than a title the parser know
157. 0 8859 1 gt This goes at the very top of an XML document so it can prepare the XML parser for the text to follow downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The encoding parameter and in fact the whole prologue is optional Without an explicit encoding parameter the XML processor will assume you want UTF 8 or UTF 16 depending on the first few bytes of the file It is inconvenient to insert exotic characters from a common terminal XML provides a shorthand called character entity references If you want a letter c with a cedilla c you can express it numerically like this 224 decimal or s xe7 hexadecimal both of which use the position of the character in Unicode as an identifier Often there may be one or more translations of a document You can keep them all together using XML s built in support for language qualifiers In this piece of XML two versions of the same text are kept together for convenience differentiated by labels para xml lang en gt There is an answer lt para gt para xml lang de gt Es gibt ein Antwort lt para gt This same system can even be used with dialects within a language In this case both are English but from different locales para xml lang en US Consult the program lt para gt para xml lang en GB Consult the programme lt para gt Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab
158. 11 is a name 1 followed by an equals sign 2 and a string 4 inside quotes 3 Two kinds of quotes are allowed double and single Quote characters around an attribute value must match downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Figure 2 11 Form of an attribute Element naming must follow the rules of XML names a generic term in the XML specification that alsc applies to names of attributes and some other kinds of markup An XML name can contain any alohanumeric characters a z A Z and 0 9 accented characters like or characters from non Latir scripts like Greek Arabic or Katakana The only punctuation allowed in names are the hyphen underscore and period The colon is reserved for another purpose which will explain later Names can only start with a letter ideograph or underscore Names are case sensitive so Para para and pArA are three different elements The following elements are well formed to do Clean fish tank lt to do gt street address 1420 Sesame Street street address lt MP3 name gt Where my doggies at lt MP3 name gt lt a3 gt goofy but legal These element names are not lt item gt Bathe the badger lt item gt 2nd phone number 785 555 1001 2nd phone number lt notes comments gt Huh lt notest tcommments gt Technically there is no limit to the length of an XML name Practically speaking
159. 3em list gt list indent 6em list gt list gt list indent 9em The universal selector can be used anywhere in the hierarchy For example given this content chapter title Classification of Bosses lt title gt sectl title Meddling Types lt title gt lt sect2 gt lt title gt Micromanagers lt title gt You can match the last two title elements with this selector chapter title The first title Is not selected since the universal selector requires at least one element to sit between chapter and title 5 3 3 2 Position Often you need to know where an element occurs in a sequence of same level elements For example you might want to treat the first paragraph of a chapter differently from the rest by making it all uppercase perhaps To do this add a special suffix to the element selector like this para first child font variant uppercase para first child matches only a para that is the first child of an element A colon followed by e keyword like irst child Is called a pseudo class in CSS It provides extra information that can t be expressed in terms of element or attribute names We saw another earlier lang Another way to examine the context of an element is to look its siblings Thesibling selector matches an element immediately following another For example title para text indent 0 J matches every para that follows a title and turns off its initial indent This works only
160. 9 1 standalone no gt 2 3 2 The Document Type Declaration There are two reasons why you would want to use a document type declaration The first is to define entities or default attribute values The second is to support validation a special mode of parsing that checks grammar and vocabulary of markup A validating parser needs to read a list of declarations for element rules before it can begin to parse In both cases you need to make declarations available and place to do that is in the document type declaration section Figure 2 4 shows the basic form of the document type declaration It begins with the delimiter DOCTYE 1 and ends with the delimiter gt 7 Inside the first part is an element name 2 which identifies the type of the document element Next is an optional identifier for the document type definition 3 which may be a path to a file on the system a URL to a file on the Internet or some other kind of unique nam meaningful to the parser The last part enclosed in brackets 4 and 6 is an optional list of entity declarations 5 called the internal subset It complements the external document type definition which called the external subset Together the internal and external subsets form a collection of declarations necessary for parsing and validation Figure 2 4 Form of the document type declaration downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 0 o e o lt DOCTYPE
161. As a bartender I have to mix martinis emphasis just lt emphasis gt lt emphasis gt right lt emphasis gt Some of my customers get pretty cranky if I slip up Luckily my new sonic screwdriver from Cybertronix 1S so accurate it gets the mixture right every time No more looking down the barrel of a kill o zap gun for this bartender lt para gt downloaded from fib ommolkcetftab ir downloaded from lib eommolketab ir blockquote chapter chapter id controls gt title Mastering the Controls title secti lt title gt Overview lt title gt lt para gt lt xref linkend controls diagram gt is a diagram of the parts of your amp productname lt para gt riqure idge9 controls driagram SEIS NOTE 7 gt lt title gt Exploded Parts Diagram lt title gt lt graphic fileref parts png gt lt figure gt lt para gt lt xref linkend controls table lee SEE NOTE B gt lists the function of the parts labeled in the diagram lt para gt table id controls table gt lt 5 SEE NOTE 9 gt title Control Descriptions lt title gt tgroup cols 2 gt thead lt row gt lt entry gt Control lt entry gt lt entry gt Purpose lt entry gt lt row gt lt thead gt lt tOOGaYy gt lt row gt lt entry gt Decoy Power Switch lt entry gt lt entry gt lt para gt Looks just like an on off toggle button but only turns on a small flashlight when pressed Very han
162. B Chapter 9 Internationalization XML was built from the ground up to support information in many different languages While you and your application may not understand markup and content in foreign languages XML makes certain that XML compliant tools let more of the world work in and share information created in whatever language they want Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 9 1 Character Encodings Throughout the book have treated characters as a sort of commodity just something used to fill ut documents But understanding characters and how they are represented in documents is of great importance in XML After all characters are both the building material for markup and the cargo it was meant to carry Every XML document has a character encoding property I ll give you a quick explanation now and a more complete description later In a nutshell it is the way the numerical values in files and streams are transformed into the symbols that you see on the screen Encodings come in many different kinds reflecting the cultural diversity of users the capabilities of systems and the inevitable cycle of progress and obsolescence Character encodings are probably the most confusing topic in the study of XML Partly this is because of a glut of acronyms and confusing names UTF 8 UCS 4 Shift JIS and SO 8859 1 Windows 3 1 Latin 1 to name a few Also hamperin
163. C standards process candidate recommendations Cascading Style Sheet See CSS catalogs 2nd CDATA character data CDATA sections 2nd CDATASection class chained xpointers channels character encoding character entities character sets CharacterData class characters CDATA sections encoding references selecting specifying human languages entities entity references escaping points PYX sets Unicode Chemical Markup Language CML child sequences class interface reference classes CDATASection CharacterData DocumentFragment DocumentType DOM EntityReference NamedNodeMap names Node NodeList nodes 2nd Processingl nstruction client side processing CML Chemical Markup Language code See also markup 2nd APIs downloaded from fib ommolkcetftab ir downloaded from lib eommolketab ir DOM events DOM languages limitations of objects parsing Perl pull parsing PIX SAX streams trees colors backgrounds borders text comments 2nd 3rd See also text 4th nodes schemas XSLT communication comparison operators compatibility of PYX complex data elements MathML complex structures narrative documents complex type compound property conditional sections 2nd configuration output element trees searching nodes subtrees types of nodes conflicts See also troubleshooting properties container element syntax container elements container nodes pointers containers
164. D See Document Type Definition Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E F G IH 1 J K L EM EN O P IQ R S T U IV W X editors elements 2nd 3rd 4th See also blocks apply templates attributes complex data CSS matching troubleshooting property conflicts documents 2nd DTDs for each formatting namespaces nodes 2nd output positioning preserve space properties RELAX NG repetition of simple type of sorting syntax trees whitespace XML XSLT Emacs text editor email MIME embedding graphics empty element syntax empty elements encoding characters 2nd references selecting specifying human languages Unicode MathML endpoints searching entities 2nd character declarations mixed content parameters references 2nd 3rd 4th unparsed downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir EntityReference class enumeration equations MathML even numbered verso pages events dispatchers handlers pull parsing PYX existential comparisons expressions Boolean node set number strings Extensible Style Language See XSL Extensible Style Language Transformations See XSLT extensions MI ME external entities 2nd external references external subsets 2nd Team LiB downloaded from fib ommolkcetftab ir downloaded from fib
165. GTDIOOGEK font weight 2 bold font srze l0pr space after l1em xsl apply templates eTOSELOBES lt xsl template gt lt The last block element a message body element The padding is set to 0 25 inches and the border is visible 2xelttemplditse maLcue9 message gt SIOIDIOCKE padding 0 25in border solid lpt black xsl apply templates fqToELOSES downloaded from lib eommolketab ir downloaded from fib ommolkcefab ir lt xsl template gt lt The inline emphasis element is set to be italic lt xsl template match emphasis gt lt fo inline font style italic xsl apply templates lt fo inline gt lt xsl template gt lt xsl stylesheet gt Many of the elements created by this stylesheet have attributes that define properties you may recognize from CSS Names like font style and border should be familiar to you already If you remember the display type property from CSS you will understand what theblock and inline elements do They are containers that shape their contents either to fit a rectangular area in a flow or to follow the inline progression of lines in a block Run the transformation on the source document and you will generate this formatting object tree lt xml version 1 0 gt fo root xmilns fo http www w3 org 1999 XSL Format gt lt fo layout master set gt lt fo simple page master master name the only page type page
166. IE 2 gt lt title gt Introduction lt title gt lt para gt Congratulations on your purchase of one of the most valuable tools in the universe The amp companyname amp productname is equipment no hyperspace traveler should be without Some of the myriad tasks you can achieve with this device are lt para gt lt itemizedlist gt lt listitem gt lt para gt Pick locks in seconds Never be locked out of your tardis again Good for all makes and models including Yale Dalek and Xngfzz lt para gt lt listitem gt listitem para Spot weld metal alloys plastic skin lesions and virtually any other material lt para gt lt listitem gt lt listitem gt lt para gt Rid your dwelling of vermin Banish insects rodents and computer viruses from your time machine or spaceship lt para gt lt listitem gt lt listitem gt lt para gt Slice and process foodstuffs from tomatoes to brine worms Unlike knife there is no blade to go dull lt para gt lt listitem gt itemizedlist lt para gt Here is what satisfied customers are saying about their amp companyname amp productname lt para gt lt comment gt of BLUE Boe Should we name the people who spoke these quotes Ed lt comment gt lt blockquote gt lt para gt It helped me escape from the prison planet Garboplactor VI I wouldn t be alive today if it weren t for my Cybertronix 9000 lt para gt lt blockquote gt lt blockquote gt lt para gt
167. L Signature was collaboratively developed by the W3C and IETF The February 2002 XML Signature Syntax and Processing is published athttp www w3 org TR xmldsig core Description XML Signature is designed to provide uniqueidentifiers for XML documents which can then be used in other XML based projects notably security projects Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 6 Publishing DocBook DocBook is a DTD for technical publications and software documentation OASI S Status The latest SGML version of DocBook is 4 2 the latest XML version of DocBook is 4 3b2 DocBook Is officially maintained by the DocBook Technical Committee of OASIS and you can find the official home page at http www oasis open org docbook index html Description DocBook is a large and robust DTD designed for technical publications such as documents related to computer hardware and software Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 7 Hypertext XHTML The Extensible Hypertext Markup Language is a reformulation of HTML in XML W3C Status XHTML 1 0 became a W3C Recommendation in January 2000 with a Second Edition in August 2002 The specification is published athttp www w3 org TR xhtml1 Modularization of XHTML which became a Recommendation in April 2001 is published athttp www w3 org TR x
168. OM trees out of files from the command line use XML LibXML my Sparser new XML LibXML a parser object This table gives us that ability to test the type of most common nodes It is not a complete list but these are the ones we are most likely to encounter and care about for this example my nodeTypes element gt attribute gt 2 text gt 3 cdatasection gt 4 entityref gt 5 entitynode gt 6 procinstruc gt 7 comment gt 8 document gt 9 2 Loop through the arguments on the command line feeding them to the parser as filenames After testing that parsing was successful apply the map proc to elems subroutine to the document node to make the needed fixes Finally write the XML back out to the file foreach my fileName ARGV my S docRef eval SdocRef S parser parse file fileName Jj duiue Parser error SE J afi 58 ys map proc to elems amp fix_iterms S docRef downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir open OUT gt SfileName or die Can t write fileName prance OUT SdgdocRef SLtoSstreingu0s close OUT j After instantiating the parser we created a hash table that maps English words for node types to the numeric codes used in the parser This will give us the ability to test what kind of node we are lookin at when we traverse through the file In the loop below that declaration we take filenam
169. Olor tan CO OLOr DISK font family monospace padding lem j message display block margin 5em padding 5em border thin solid brown background color wheat whitespace normal j to before display block downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Color DISCE concent Tos s j from before display block colors Dilack Convent From V j subject before color DLSOE content Subject j to rom subject 4 dqisplevse Dlock color blue font size large j emphasis tontc style itali j name font weight bold j villain color red font weight bold To apply this stylesheet you need to add a special instruction to the source document It looks like this xml stylesheet type text css href ex2 memo css This is a processing instruction not an element It will be ignored by any XML processing software that doesn t handle CSS stylesheets To see the result you can open the document in a web browser that accepts XML and can format with CSS Figure 1 1 shows a screenshot of how it looks in Safari version 1 0 for Mac OS X Figure 1 1 Screenshot of a CSS formatted document downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Io Sarah Bellum From Colonel Timeslip Subject Robot sitting instructions T ot Thanks for watching my robot pal Zonky while I m away He
170. PE book SYSTEM xmlstuff dtds barebonesdb dtd lt ENTITY companyname Cybertronix gt be OEE NOTE 1 gt lt ENTITY productname Sonic Screwdriver 9000 gt book lt title gt amp productname User Manual lt title gt see SEE NOTE X gt lt author gt Indigo Riceway lt author gt lt preface id preface gt lt title gt Preface lt title gt Lect t0 abour gt lt title gt Availability lt title gt lt para gt The information in this manual is available in the following forms lt para gt downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir lt orderedlist gt Tios SM NOISE 2 gt lt listitem gt lt para gt Instant telepathic injection lt para gt lt listitem gt lt listitem gt lt para gt Lumino goggle display lt para gt lt listitem gt lt listitem gt lt para gt Ink on compressed dead arboreal matter lt para gt lt listitem gt lt listitem gt lt para gt Cuneiform etched in clay tablets lt para gt lt listit orderedlist lt para gt The amp productname is sold in galactic pamphlet boutiques or wherever amp companyname equipment can be purchased For more information or to order a copy by hyperspacial courier please visit our universe wide Web page at lt systemitem role url http www cybertronix com sonic screwdrivers html systemitem para lt sectl gt amp lee OEE NOTE 4 gt lt preface gt chapter id intro gt amp lc Seg NO
171. Pointer became a W3C Recommendation in March 2003 The specification is published in four parts The XPointer Framework can be found athttp www w3 org TR xptr framework The XPointer xmlns Scheme can be found athttp www w3 org TR xptr xmlns and the XPointer element Scheme can be found at http www w3 org TR xptr element The XPointer xpointer Scheme remains a Working Draft and can be found athttp www w3 org TR xptr xpointer Description downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XPointer is designed to be used as the basis for a fragment identifier for any URI reference that locates a resource of Internet media type text xml or application xml Based on the XML Path Language XPath XPointer supports addressing into the internal structures of XML documents It allows for examination of a hierarchical document structure and choice of its internal parts based on properties such as element types attribute values character content and relative position XQuery XML Query Language provides database like query facilities for accessing web documents W3C Status XQuery is under development at the W3C The most recent Working Drafts were published in May 2003 They include the XQuery 1 0 and XPath 2 0 Data Model athttp www w3 org TR xpath datamodel XQuery 1 0 and XPath 2 0 Functions and Operators athttp www w3 org TR xpath functions XQuery 1 0 and XPath 2 0 Formal Semantics at h
172. SL FO the FO stands for Formatting Objects de format It soon became obvious that XSLT was useful in a wider context than just formatting documents It can turn an XML document into just about any form you can imagine The language is generic using rules a to describe what to output for various element types Mr Clark has expressed surprise that XSLT is bein many other applications but it is testament to the excellent design of this standard that it has worked s XSLT is an application of XML This means you can easily write XSLT in any non validating XML editor Y validate XSLT because there is no DTD for it An XSLT script contains many elements that you define yo downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir DTDs do not provide that kind of flexibility However you could use an XML Schema usually just checl formedness and rely on the XSLT processor to tell me when it thinks the grammar is wrong An XSLT processor is a program that takes an XML document and an XSLT stylesheet as input and outpt transformed document Thanks to the enthusiasm for XSLT there are many implementations available MSXML system is probably the most commonly used Saxon http saxon sourceforge net is the most and advanced Others include Apache s Xalan http xml apache org xalan j index html and GNOME s http www xmlsoft org XSLT html Besides using a programming library or command line tool you could also use a we
173. SS boxes Areas are somewhat more general allowing for alternative writing modes that require generic terminology like start and before instead of top and left Still you will find XSL s areas very familiar if you ve worked with CSS before Figure 8 3 shows the area model and its components Figure 8 3 The area model Every area maps out a content rectangle a reference frame against which the formatter positions children and applies space It separates two buffers of space amargin on the outside and padding on the inside The visible manifestation of the content rectangle is called theborder It is bound on downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir the outside by the border rectangle and on the inside by the padding rectangle 8 3 1 Area Stacking An area s children reside inside its content rectangle They may be positioned in explicit terms but more frequently they re placed orstacked according to an algorithm The direction in which this Stacking proceeds depends on the writing mode in use for that area For example in European writing modes block areas progress from top to bottom and the inline areas go from left to right These are called the block progression direction and inline progression direction respectively XSL is designed to support any writing mode s directionality XSL Supports three basic modes referred to by their inline and block progression directions e Left to right
174. SS processor how to format it If display Is set to block the element begins on its own line If it s set toinline the element begins on the line that the previous element or character data finished on The valuenone indicates that the element is invisible This model breaks down for complex objects like tables A table is a unique formatting structure with cellular regions that can contain blocks or inlines The discussion of this formatting is too complexfor the scope of this chapter Because HTML browsers have an implicit CSS stylesheet built in there is no need to define a display value for any HTML elements Thep element always displays like a block and tt displays as an inline However the same is not true for generic XML languages The processor has no prior knowledge of the language so it is forced to guess Declaring the display property for all elements is recommended 5 4 4 Blockish Properties Around every block is an invisible box that shapes its content and keeps a healthy distance from its neighbors Figure 5 10 shows all the parts of this box model Immediately surrounding the content of the block is a rectangular buffer of space called thebounding box Its distance from the content is known as padding The perimeter of this region called the boundary is sometimes displayed as a rule or border on one two three or all four sides The thickness of these rules is measured outward Outside the boundary is another envelope
175. Slat lt element name 2 footnote lt oneOrMore gt lt parentRef name para content gt lt oneOrMore gt lt element gt lt start gt lt grammar gt The footnote pattern relies on its parent grammar to define a pattern forpara 4 4 7 3 Merging grammars You can merge grammars from external sources by using include as a child of grammar Like externalRef include Uses an href attribute to source in the definitions However it actually incorporates them in the same context unlikeexternalRef which keeps scopes for named patterns separate One use for include Is to augment an existing definition with more patterns Suppose for example this pattern is located in block rng grammar xmlns http relaxng org ns structure 1 0 Seat rer neme block class gt eer ane define name block class gt lt choice gt lt element name title gt lt text gt lt element gt element name para gt lt text gt element choice define grammar can add more items to this class by including it like so grammar xmlns http relaxng org ns structure 1 0 include href block rng gt create lt oneOrMore gt lt element name section gt ref names block class element oneOrMore downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir a esa bas we define name block class combine choice gt element name poem gt text el
176. Support CALS group including a popular table formatting document type called CALS Tables And then capping off this successful start the International Standards Organization ISO ratified a standard for SGML ISO 8879 1986 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir SGML was designed to be a flexible and all encompassing coding scheme Like XML it is basically a toolkit for developing specialized markup languages But SGML is much bigger than XML with a more flexible syntax and lots of esoteric parameters It s so flexible that software built to process it is complex and generally expensive and its usefulness is limited to large organizations that can afford both the software and the cost of maintaining SGML environments The public revolution in generic coding came about in the early 1990s when Hypertext Markup Language HTML was developed by Tim Berners Lee and Anders Berglund employees of the European particle physics lab CERN CERN had been involved in the SGML effort since the early 1980s when Berglund developed a publishing system to test SGML Berners Lee and Berglund created an SGML document type for hypertext documents that was compact and efficient It was easy to write software for this markup language and even easier to encode documents HTML escaped from the lab and went on to take over the world However HTML was in some ways a step backward To achieve the simplicity necessary to be t
177. UCS 2 and UCS 4 A straight mapping of 16 bit Unicode is UCS 2 Every character occupies two bytes in the document Likewise 32 bit UCS is represented by the encoding UCS 4 and requires four bytes per character Since Unicode and UCS are just big code tables assigning integers to characters it is not difficult to understand these encoding schemes You can convert a US ASCII or Latin 1 file into UCS 2 simply b adding a 0x00 byte in front of every ASCII byte Make that three 0x00 bytes to convert to UCS 4 UCS 2 and UCS 4 have issues about byte ordering On some systems including Intel and VAX architectures multibyte numbers are stored least significant byte first The number 0x1234 would be stored as 0x34 followed by 0x12 This is called alittle endian architecture In contrast many Unix systems such as Solaris put the most significant byte first which is calledbig endian architecture UCS 2 and UCS 4 generally follow the big endian convention As a developer this is very important tc know because software written for a little endian system will need to transpose adjacent bytes as it reads them into memory As a user you only need to know if your software is aware of UCS 2 or UCS 4 and you can trust that it will be handled correctly On some systems namely Win32 every Unicode file starts with the a special character known as the byte order mark BOM with the value U FEFF This is the zero width no break space character which is typically
178. Word and Adobe FrameMaker save data in a binary format by default saving disk space and perhaps speeding up file transfers HTTP offers compression for transmission which helps reduce this cost e Many kinds of data are not suited for embedded markup XML is most useful for text data with hierarchical structure It does not offer much for binary data For example raster graphic images are long streams of binary data unreadable to anyone until passed through a graphic viewing program This binary data may contain dangerous characters that would need to be escaped Binary data is optimized for size and speed of loading two qualities that would be hindered by XML e XML may raise expectations too high Quite often software vendors tout XML support as a grea new feature in their product only to disappoint users with poor implementation For example the early version of Adobe FrameMaker s XML export capability was nearly unusable as much o the data was structured badly was missing information changed figure filenames and so on Instead of viewing it as a magic bullet developers should approach XML as a framework in which intelligent design focusing onthe quality of markup structures can achieve magnificent results Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 2 Streams and Events The stream approach treats XML content as a pipeline As it rushes past you have one ch
179. XML documents into other XML documents Chapter 8 describes and demonstrates the use of Extensible Stylesheet Language Formatting Objects XSL FO to create print representations of XML documents Chapter 9 examines internationalization issues with XML including character encoding issues language specification and the use of MIME media type identifiers Chapter 10 describes various approaches to processing XML documents and creating programs around XML Appendix A lists resources which may be useful in your further exploration of XML Appendix B provides a list of the many standards at the heart of XML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Style Conventions Items appearing in this book are sometimes given a special appearance to set them apart from the regular text Here s how they look Italic Used for commands email addresses URIs filenames emphasized text first references to terms and citations of books and articles Constant width Used for literals constant values code listings and XML markup Constant width italic Used for replaceable parameter and variable names Constant width bold Used to highlight the portion of a code listing being discussed Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Examples The examples from this book are freely downloadable from the bo
180. XSL as flexible as possible It is device agnostic downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Supporting a variety of media from synthesized speech to on screen display It is designed for high typographic quality It is multilingual with support for bidirectional and vertical scripts most modern fonts such as OpenType and the full set of Unicode characters At the time of this writing find that XSL is still rather rough around the edges Early adopters will find a variety of tools available with varying degrees of conformance to the standard but none offer the kind of control you have with a proprietary publishing system like FrameMaker or Quark If you want a WYSIWYG environment where you can specify pagebreaks and see the document repaginate before your eyes you will not get that with XSL The choice of whether to use XSL may depend on two things First how much control do you need while authoring the document Graphic designers need a very high level of control with instant feedback as they shape and sculpt a document XSL implementations out there now do not offer anything like that Second how much of your workflow is automated If you have huge stacks of documents to process as is the case with legal departments and doctors offices XSL can help It works behind the scenes with no human presence required Justset up your stylesheet write a batch processing program and let it go Team LIB
181. a models directives call template display types CSS DocBook DTDs narrative documents XSL FO Document Content Description DCD Document Definition Markup Language DDML document elements 2nd document instance document models Document Object Model DOM 2nd document prolog document tree document type declaration Document Type Definition DTD 2nd 3rd 4th declaration importing modular schemas 2nd 3rd customizing declarations downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir document prologs narrative documents documentation DocumentFragment class documents area model authoring character escaping Coo describing documents media templates DTDs elements 2nd footnotes formatting human linking markup MathML models 2nd namespaces narrative blocks complex structures DocBook DTDs flow linked objects metadata XHTML points printing prologs 2nd declarations schemas schemas 2nd stylesheets applying associating limitations of SVG transformation default rules elements executing formatting history of matching nodes modularity naming overview of downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir precedence redirecting templates trees searching nodes subtrees types of nodes viewing well formedness XML XML TEI DocumentType class DOM Document Object Model 2nd 3rd drivers SAX DT
182. abel Slabel gt Aeel veer gt Parc xsBl btext lt xsl value of select ref gt exeltrext e xelt texto lt xsl template gt lt Set up the instructions list gt lt xsl template match instructions gt lt h2 gt Steps lt h2 gt lt OL gt xsl apply templates lt ol gt lt xsl template gt Handle each item a lt step gt in the instructions list gt lt xsl template match step gt LL xsl apply templates t aM lt xsl template gt lt xsl stylesheet gt You will notice that each rule in the verbal description has a correspondingtemplate element that contains a balanced well formed piece of XML Namespaces help the processor tell the difference between what is an XSLT instruction and what is markup to output in the result tree In this case XSLT instructions are elements that have the namespace prefixxs1 The match attribute in each template element assigns it to a piece of the source treeusing an XSLT pattern which is based on XPath A template is a mixture of markup text content and XSLT instructions The instructions may be conditional statements if these conditions are true output this content formatting functions or instructions to redirect processing to other nodes The elementapply templates for example tells the XSLT engine to move processing to a new set of context nodes the children of the current node downloaded from lib ommolketab ir dow
183. act The following describes how a DTD defines a document type A DTD declares a set of allowed elements You cannot use any element names other than those in this set Think of this as the vocabulary of the language e A DTD defines a content model for each element The content model is a pattern that tells what elements or data can go inside an element in what order in what number and whether they are required or optional Think of this as the grammar of the language e A DTD declares a set of allowed attributes for each element Each attribute declaration defines the name datatype default values if any and behavior e g if it is required or optional of the attribute e A DTD provides a variety of mechanisms to make managing the model easier for example the use of parameter entities and the ability to import pieces of the model from an external file 4 2 1 Document Prolog According to the XML Recommendation all external parsed entities including DTDs should begin with a text declaration It looks like an XML declaration except that it explicitly excludes the standalone property If you need to specify a character set other than the default UTF 8 seeChapter 9 for more about character sets or to change the XML version number from the default 1 0 this is where you would do it If you specify a character set in the DTD it won t automatically carry over into XML documents that use the DTD XML documents have to specify th
184. address gt lt street gt 471 Skipstone Lane lt unit gt 4 A lt unit gt lt street gt lt city gt Emerald City lt city gt lt county gt Greenhill lt county gt CounLry gt O2 country lt postalcode gt 885JKL lt postalcode gt lt address gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir person employed fulltime pid P270405 gt name lt first gt Meeble lt first gt amp elastoBlgbDugc lasto e JuUniorz7 lt name gt lt age gt 39 lt age gt lt gender gt male lt gender gt lt person gt person employed parttime pid P273882 gt name lt first gt Mable lt first gt lt last gt Bigbug lt last gt lt name gt lt age gt 36 lt age gt lt gender gt female lt gender gt lt person gt lt person pid P472891 gt lt name gt lt first gt Marble lt first gt lt last gt Bigbug lt last gt lt name gt age 11 age lt gender gt male lt gender gt lt person gt census record Let s start putting together a DTD The first declaration is for the document element lt ELEMENT census record date address person t This establishes the first rules for the CensusML language 1 there is an element namedcensus record and 2 it must contains one date element one address element and at least one person element If you leave any of these elements out or put them in a different order the document will be invalid Note that
185. aded from lib ommolketab ir downloaded from fib ommolkcefab ir 4 The length of the result string default being the length of the pattern in the second argument For example this xpointer would locate the ninth occurrence of the word excelsior in a document xpointer string range excelsior 9 And this next xpointer would return a range for the eight characters following the string username with one space for padding inside an element withid user123 Note that the indexing for characters is different from that for points Here the first character s position is 1 not zero xpointer string range id userl23 username 1 8 Note that setting the length the last argument to zero would result in a range for a zero length string This collapsed range is effectively the same as a single point An interesting thing about string range Is that it ignores the boundaries of nodes It s as if all the content were dumped into a plain text file without XML tags Effectively text nodes are concatenated together into one long string of text So in the following markup free as in lt em gt freedom lt em gt This xpointer would match it whether the em tags were there or not xpointer string range free as in freedom 6 4 4 4 Finding range endpoints The functions start range and end range locate the points at the beginning and end of a range respectively Each takes one argument a location set If that
186. aded until the user actuates the link A completely different application might be to use xpointers as hooks for annotations stored in a local database The user agent may use this information to insert icons into the formatted view of the target document that when selected bring up another window containing downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir commentary So by not explaining how XPointer is meant to be used its flexibility is enhanced Whatever Happened to XLink Plans for XLink were announced in the early days of XML There were great expectations for it The limitations of HTML links were to give way to a whole new world of possibilities from customizable navigation views to third party collections of documents a document soup if you will The recommendation is divided into two levels simple and extended Simple covers the traditional inline hypertext links that we are all familiar with Extended links are an exciting new mechanism describing links between resources from either point or even a third document Now it is two years after XLink reached recommendation status it took four years just to reach that point and hardly any implementations are available None of the web browsers available today offer extended link Support and only a few support even simple links Why XLink failed to capture the imagination of developers and XML users may have to do with the popularity of
187. ader section with title and other metadata followed by the text itself which is broken into individual lines of poetry Example 8 2 A TEI XML document lt xml version 1 0 gt lt DOCTYPE TEI 2 SYSTEM http www uic edu orgs tei lite teixlite dtd SIBI 4 lt The metadata TEI has a rich vocabulary for describing a document which is important for scholarly work lt teiHeader gt lt fileDesc gt lt titleStmt gt lt title gt Shall I Compare Thee to a Summer s Day lt title gt lt author gt William Shakespeare lt author gt lt titleStmt gt epublacacionsbpmte 5o ELectronic version by Erik Ray 2003 03 09 This transcription is in the public domain lt p gt eTpublicationstmb lt S0u urceDesc gt lt p gt Shakespeare s Sonnets XVIII lt p gt lt sourceDesc gt lt fileDesc gt lt teiHeader gt lt The body of the document where the sonnet lives lg is a group of lines and 1 is a line of text SLSXL SDOOY Sg lt l gt Shall I compare thee to a summer s day 1 lt l gt Thou art more lovely and more temperate lt 1 gt l Rough winds do shake the darling buds of May 1 lt 1 gt And summer s lease hath all too short a date 1 lt 1 gt Sometime too hot the eye of heaven shines l1 l And often is his gold complexion dimm d lt 1 gt lt l gt And every fair from fair sometime declines lt 1 gt lt l gt By chance or nature s changing course untr
188. age that does not start a chapter Again the distinctive layout involves right justifying header and footer Below is the stylesheet portion containing page master definitions The template matching the root node in the source document calls a named template that sets up the page masters and also the page sequence masters lt xml version 1 0 gt xsl stylesheet version 1 0 xmlns xsl http www w3 org 1999 XSL Transform xmlns fo http www w3 org 1999 XSL Format glec ROOT RULE Set up page layout and main flow downloaded from lib ommolketab ir downloaded from lib eommolketab ir lt xsl template match gt LIOI OOC lt fo layout master set gt lt xsl call template name page masters gt xsl call template name page sequence masters gt lt fo layout master set gt lt xsl apply templates gt lt Ioiroot gt lt xsl template gt PAGE MASTERS Where we define layout and regions for page types lt xsl template name page masters gt aee Even numbered first page of a chapter fo simple page master master name chapter first verso page height 9in page width 7in margin left 1in inargin ruighb lin margin top 0 5in margin bottom 0 4in trice pody gt lt fo region body luargin Ltopse 2 51m5 jargin bDottoms 0 6in J gt 1 header gt lt fo region before region name region first verso before extent lin I gt gt TOOLE gt lt fo re
189. ails anc small mistakes The deadline for comments finally arrives and the working group goes back to work making revisions and changes Satisfied that the group has something valuable to contribute to the world the Director takes the candidate recommendation and blesses it into aproposed recommendation It must then survive the scrutiny of the Advisory Committee and perhaps be revised a little more before it finally graduates into a recommendation The whole process can take years to complete and until the final recommendation is released you shouldn t accept anything as gospel Everything can change overnight as the inext draft is posted and many a developer has been burned by implementing the sketchy downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir details in a working draft only to find that the actual recommendation is a completely different beast If you re an end user you should also be careful You may believe that the feature you need is coming only to find it was cut from the feature list at the last minute It s a good idea to visit the W3C s web site http www w3 org every now and then You ll find news and information about evolving standards links to tutorials and pointers to software tools It s listed along with some other favorite resources inAppendix B 1 1 4 A Constellation of Standards Many people agree that spending money is generally more fun than saving i
190. al requirement providing methods that deal with element tags attributes processing instructions and character data The others override default behavior of the core API To ensure that your handler classes are written correctly the Java version of SAX includes interfaces program constructs that describe methods to be implemented in a class The characters method of the content handler may be called multiple times for the same text node as SAX drivers are allowed to split text into smaller pieces Your code will need to anticipate this and stitch text together if necessary The entity resolver overrides the default method for resolving external entity references Ordinarily i is assumed that you just want all external entity references resolved automatically and the driver tries to comply but in some cases entity resolution has to be handled specially For example a resource located in a database would require that you write a routine to extract the data since it is an application specific process The core API doesn t create events for lexical structures like CDATA sections comments and DOCTYPE declarations If your environment provides the DTD handling extension you can write a handler for that If not then you should just assume that the CDATA sections are treated as regular character data comments are stripped out and DOCTYPE declarations are out of your reach The error handler package gives the programmer a graceful way to deal
191. alse gt eic Solet Here the data is stored in a tabular form within adict dictionary element Each row is a pair of elements the first a key the name of a property and the second a value Values come in different types such as the Boolean true or false and integer values you see here The property SpeechRecognition Is assigned the boolean value FALSE which means that this feature is turned off downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir in the program The property Level difficulty level is set to 1 because I m a lousy chess player Here s a more complex example It s the property list for system sounds com apple soundpref plist lt xml version 1 0 encoding UTF 8 gt lt DOCTYPE plist PUBLIC Apple Computer DTD PLIST 1 0 EN DTDs PropertyList 1 0 dtd gt lt plist version 1 0 gt SOICL lt key gt AlertsUseMainDevice lt key gt lt key gt Devices lt key gt sdi lt key gt InputDevices lt key gt Smp Xkey AppleDBDMAAudioDMAEngine 0 key Slo lt key gt Balance lt key gt lt key gt DeviceLevels lt key gt lt integer gt 1l lt integer gt lt real gt 0 0 lt real gt lt array gt lt real gt 0 5 lt real gt lt real gt 0 5 lt real gt array lt key gt Level lt key gt lt real gt 0 5 lt real gt lt e dict gt SIC EES lt key gt OutputDevices lt key gt SOJQpD lt key gt AppleDBDMAAudioDMAFngine 0 lt key gt eun lt key gt Balance lt
192. alue and conditionally output text The idea is that whenever something is found that is no right with the document the Schematron processor should output a message to that effect You can think of Schematron as a language for generating validation reports One interesting feature of Schematron is that its documentation is a part of the language itself Rather than rely on comments or the namespace hack from RELAX NG this language explicitly defines elements and attributes to hold commentary The root element schema has an optional child title to name the schema and pattern elements have a name attribute for identifying rule groups A Schematron validator will use that attribute to label each pattern of testing in output There is also a set of tags for formatting text borrowed from HTML such asp and span Let s look at an example Below is a schema to test a report document There are two kinds of reports we allow one with a body and another with a set of at least three sections schema xmlns http www ascc net xml schematron lt title gt Test Report Document Validity lt title gt pattern name Type 1 gt lt p gt Type 1 reports should have a title and a body lt p gt lt rule context gt lt assert test report gt Wrong root element This isn t a report lt assert gt lt rule gt rule context report gt assert test title Darn It s missing a title lt assert gt report test title gt Yup found a title
193. ance to work with it no look ahead or look behind It is fast and efficient allowing you to work with enormous files in a short time but depends on simple markup that closely follows the order of processing In programming jargon a stream is a sequence of data chunks to be processed A file for example Is a sequence of characters one or more bytes each depending on the encoding A program using this data can open a filehandle to the file creating a character stream and it can choose to read in data in chunks of whatever size It chooses Streams can be dynamically generated too whether from another program received over a network or typed in by a user A stream is an abstraction making the source of the data irrelevant for the purpose of processing To summarize here are a stream s important qualities e t consists of a sequence of data fragments e he order of fragments transmitted is significant e he source of data e g file or program output is not important XML streams are more clumpy than character streams which are just long sequences of characters An XML stream emits a series of tokens or events signals that denote changes in markup status For example an element has at least three events associated with it the start tag the content and the end tag The XML stream is constructed as it is read so events happen in lexical order The content of an element will always come after the start tag and the end tag will
194. and that role powerful class mighty overrides para first child 3 More specific genealogical descriptions win over less specific chains SOchapter gt para has precedence over para but not over title para Pseudo elements don t count here 4 If the selectors are still in a dead heat there s a tie breaking rule the one that appears later in the stylesheet wins out Property value conflicts are resolved one property at a time One rule might be more specific than another but set only one property other properties may be set by a less specific rule even though one of the rule s properties has been overridden So in our earlier example thefirst hi in an element gets the color red not blue Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 5 4 Properties The three levels of CSS defineso many properties can t cover them all here There are over 120 in level 2 alone Instead I ll cover the basic categories you are likely to encounter and leave more exhaustive descriptions to books specializing on the topic 5 4 1 Inheritance CSS properties can be passed down from a container element to its child This inheritance principle greatly simplifies stylesheet design For example in the document element rule you can set a font family that will be used throughout the document Wherever you want to use a different family simply insert a new property for a rule and i
195. andards Organizations ISO Visit the International Organization for Standardization a worldwide federation of national standards organizations at http www iso ch W3C The World Wide Web Consortium athttp www w3 org oversees the specifications and guidelines for the technology of the World Wide Web Check here for information about CSS DOM X HTML MathML XLink XML XPath XPointer XSL and other web technologies Unicode Consortium The organization responsible for defining the Unicode character set can be visited at http www unicode org OASIS The Organization for the Advancement of Structured Information Standards is an international consortium that creates interoperable industry specifications based on public standards such as XML and SGML See the web site at http www oasis open org IETF The Internet Engineering Task Force is a less formal organization devoted to the creation of specifications for Internet information exchange The IETF focuses primarily on protocols notably HTTP DNS and SMTP It also does some XML work in its MIME type efforts and through its BEEP protocol work See the web site athttp www ietf org Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LIB A 4 Tools GNU Emacs An extraordinarily powerful text editor and so much more Learn all about it at http www gnu org software emacs emacs html psgml An Emacs major m
196. anguage XML has unleashed a torrent of new acronyms standards and rules that have left some in the Internet community wondering whether it is all really necessary After all HTML has been around for years and has fostered the creation of an entirely new economy and culture so why change a good thing XML isn t here to replace what s already on the Web but to create a more solid and flexible foundation It s an unprecedented effort by a consortium of organizations and companies to create an information framework for the 21st century that HTML only hinted at To understand the magnitude of this effort we need to clear away some myths First in spite of its name XML is not a markup language rather it s a toolkit for creating shaping and using markup languages This fact also takes care of the second misconception that XML will replace HTML Actually HTML is taking advantage of XML by becoming a cleaner version of itself called XHTML Anc that s just the beginning XML will make it possible to create hundreds of new markup languages to cover every application and document type The standards process will figure prominently in the growth of this information revolution XML itself is an attempt to rein in the uncontrolled development of competing technologies and proprietary languages that threatens to splinter the Web XML creates a playground where structured informatior can play nicely with applications maximizing accessibility without sacri
197. any program that takes an XML document as input and does something witt it A program that reads an XML document parses it and produces formatted output is an XML processor See also parser XML Schema An alternative to DTDs for document modeling schemas are written as XML and like DTDs define the elements entities and content model of documents Schemas have many additiona capabilities such as data type control and content restrictions XPath XML Path Language A language used to address parts of an XML document XPath locator syntax uses core functions based on the node hierarchy of a document and evaluates expressions to determine a location object XPath locations are used by XSLT and XPointer downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XPointer XML Pointer Language A special scheme based on XPath that identifies locations using special extensions to URIs XPointer locations support the use of ID attributes for absolute location references in an XML document and can step through the node hierarchy to find specific elements XSL Extensible Stylesheet Language A specification for converting XML documents to formatted results Extensible Stylesheet Language includes two subspecifications XSL FO and XSLT See alsoXSLT and See also XSL FO XSL FO A vocabulary for describing formatted documents typically for print media XSLT Extensible Stylesheet Language Transformations
198. anything over 50 characters is probably too long Inserting whitespace characters tab newline and space inside the tag is fine as long as they aren between the opening angle bracket and the element name These characters are used to separate attributes They are also often used to make tags more readable In the following example all of the whitespace characters are allowed boat type trireme gt lt crewmember alass rower gt Dronicu us baboriusc crewmembe r gt There are a few important rules about the tags of container elements The names in the start and end tags must be identical An end tag has to come after never before the start tag And both tags have to reside within the same parent element Violating the last rule is an errorcalled overlapping It s an ambiguous situation where each element seems to contain the other as you can see here zacpon r b de aux pusle b These untangled elements are okay a No problem lt a gt lt b gt here lt b gt Container elements may contain elements or character data or both Content with both characters downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir and elements is called mixed content For example here is an element with mixed content lt para gt I like to ride my motorcycle lt emphasis gt really lt emphasis gt fast lt para gt 2 4 2 Attributes In the element start tag you can add more information about the element in the
199. appropriate for the kind of cross reference we want 7 5 5 2 Parameters Like subroutines from programming languages named templates can accept parameters from the templates that call them This is a way to pass extra information to the template that it needs for processing For example you may have a template that creates a highlighted node or sidebar in a formatted document You can use a parameter to add some text to the title to set the tone tip caution warning information and so on Here is how that might look lt programlisting gt lt xsl template match warning gt xsl call template name generic note gt xsl with param name label gt Look out xsl with param xsl call template lt xsl template gt lt xsl template match tip gt xsl call template name generic note gt xsl with param name label gt Useful Tip lt xsl with param gt xsl call template lt xsl template gt lt xsl template match note gt xsl call template name generic note lt xsl template gt lt xsl template name generic note gt xsl param name label gt Note lt xsl param gt lt blockquote class note gt eos lt xsl value of select S label gt lt xsl value of select title gt edo xsl apply templates blockquote lt xsl template gt This example creates a named template called generic note that takes one parameter named label Each template calling generic note may define th
200. arly important to us because it is the default character encoding for XML documents If you do not set the character encoding in the XML declaration explicitly XML parsers are supposed to assume the document is encoded with UTF 8131 3 see RFC 2279 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The main attraction of UTF 8 is that it allows Unicode characters to be included in documents without posing any danger to legacy text handling software It was originally called UTF FSS UTF File Systen Safe because it was designed with the sensitivity of Unix file system utilities in mind Recall from th last section that wide 2 byte and 4 byte characters from UCS 2 and UCS 4 pose a risk because they may be decomposed into bytes that resemble reserved characters UTF 8 encoded text uses variable length strings of bytes to represent each Unicode UCS character The first byte describes the type of byte sequence If its value is between 0x0000 and 0x007F 0 through 127 then it will be interpreted as an ASCII character Files and strings containing only 7 bit ASCII characters have the same encoding under US ASCII and UTF 8 If the first byte is 0x0080 or greater a number of bytes following it will be used to determine the Unicode UCS character Table 9 2 shows the encoding algorithm for UCS The algorithm is the same for Unicode if you substitute 2 byte code positions but only the first four rows in the table apply
201. arning before content WARNING font weight bold color red Figure 5 11 A warning inside a border 5 4 4 4 Alignment and indentation text align IS a property that defines the alignment or justification of lines in a paragraph downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Sometimes you may want a crisp border on both the left and right sides of a column At other times you may want a ragged right or left or centered text The following values are supported left Align text with the left border ragged right CLONC Align text with the right border ragged left center Center each line within the block ragged left and right Tub Expand each line to reach both left and right borders of the block Left justification is used by default in most CSS processors Note thatleft and right are absolute and independent of text direction The text indent property indents the first line of a block A positive or negative absolute length can be specified or the indent can be given as a percentage of the width of the block 5 4 5 Text Properties So far we ve talked about blocks as containers of text Now let s focus on the text itself This section lists some properties for controlling how character data looks and behaves such as font types font styles and color 5 4 5 1 Font family A typeface has several parameters that control its appearance such as size weight and style The
202. as whether the current writing mode is horizontal or vertical An FO can contain other FOs creating a structure that propagates inheritance of properties Some properties have a direct result on the formatting of an FO instance For example setting the downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir color will have an immediate and obvious effect on text Other properties set constraints that may or may not come into play Widow and orphan settings for paragraphs are only applicable then the paragraph straddles a pagebreak In some cases properties may override other properties when a rule of aesthetics would be violated An FO creates or helps to create an abstract positional framework called an area For every area an FO specifies its position on the page how to arrange and display its children and whether any other decoration such as a border is required For example a single character will be formatted intoan area large enough to hold one glyph 8 1 3 Print Screen and Beyond Being device agnostic means XSL has to support both scrollable online presentation and the printed page Fortunately the online and print worlds have much in common The basic way of fitting conten in flows is the same and both support the notion of floating objects sidebars and footnotes marginalia and headers and footers But there is much that is different Online representations typically involve one long uninterrupt
203. at 1 lt fo repeatable page master alternatives gt lt fo conditional page master reference master reference chapter other verso page position rest odd or even even J gt lt fo conditional page master reference master reference chapter other recto page position rest odd or even odq n fo conditional page master reference master reference chapter first verso page position first odd or even even J gt lt fo conditional page master reference master reference chapter first recto page position first odd or even odd j gt lt fo repeatable page master alternatives gt lt fo page sequence master gt lt xsl template gt downloaded from lib ommolketab ir downloaded from lib ommolketab ir 8 6 3 Top Level Elements and Flows like to structure my XSLT stylesheets with the outermost container elements first So the next two templates match book and its children which include chapter preface and the like The second template includes the flow and static flow FOs Recall that static flows are used for small single page items like headers and footers lt xsl template match book gt xsl apply templates lt xsl template gt lt xsl template match chapter appendix glossary bibliography index colophon preface dedication foreword toc gt lt fo page sequence master reference chapter force page count odd lt START OF CHAPTER ON ODD PAGE gt
204. at http www w3 org TR SVG SVG 1 1 like XHTML 1 1 modularized SVG and the January 2003 Recommendation is at http www w3 org TR SVG11 That modularization was used to produce the SVG Mobile Profiles SVG Tiny and SVG Basic also published in January 2003 at http www w3 org TR SVGMobile Work on SVG 1 2 is ongoing and the latest drafts can be found at http www w3 org TR SVG12 Description SVG Is a language for describing two dimensional vector and mixed vector raster graphics in XML SMIL The Synchronized Multimedia Integration Language is an HTML like language for creating multimedia presentations W3C Status The SMIL 1 0 specification became a W3C Recommendation in J une 1998 It is published at http www w3 org TR REC smil Description SMIL allows a set of independent multimedia objects to be integrated into a synchronized multimedia presentation While SMIL itself hasn t caught on some important pieces of SMIL are now in SVG downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 10 Science MathML The Mathematical Markup Language for XML describes mathematical notation W3C Status MathML 2 0 became a W3C Recommendation in February 2001 The specification is published at http www w3 org TR MathML2 Description MathML is an XML application for descr
205. at s a low level operation prone to bugs and requiring technical ability It s also getting away from the point of DTDs which is to create a kind of metadocument a formal description of a markup language Programming languages aren t portable and don t work well as a way of conveying syntactic and semantic details So we have to conclude that DTDs don t go far enough in describing a markup language To make matters worse what the DTD will reject as bad markup are often trivial things For example the contents of aate and name are not in the specific order required by their element declarations This seems unnecessarily picayune but it s actually very difficult to write a content model that allows its children to appear in any order downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir To illustrate the problem let s try to make thedate more flexible so that it accepts children in any order The best can think of is to write the declaration like this lt ELEMENT date year month day day month month year day day year day month year year month Pretty ugly isn t it And that s only with three child elements This is another serious drawback of DTDs Perhaps the most damaging limitation of DTDs is the lockdown of namespace Any element in a document has to have a corresponding declaration in the DTD No exceptions This is fundamentally at odds with XML
206. ate a subdocument on its own you can usually perform a well formedness check if it has no more than one tree The parser will think it s looking at a lone document without a prolog This makes it a lot easier to manage a large document especially if you have different people working on it at the same time This gets tricky if your subdocument uses entities defined in the main document however The syntax just shown for declaring an external entity uses the keywordsvsTEM followed by a quoted string containing a filename This string is called asystem identifier and is used to identify a resource by location The quoted string is actually a URL so you can include files from anywhere on the Internet For example lt ENTITY catalog SYSTEM http www bobsbolts com catalog xml gt The system identifier suffers from the same drawback as all URLs if the referenced item is moved the link breaks To avoid that problem you can use a public identifier in the entity declaration In theory a public identifier will endure any location shuffling and still fetch the correct resource For example lt ENTITY faraway PUBLIC BOB FILE Catalog EN http www bobsbolts com catalog xml Of course for this to work the XML processor has to know how to use public identifiers and it must be able to find a catalog that maps them to actual locations In addition there s no guarantee that the catalog is up to date A lot can go wrong Perhaps for thi
207. ave been resolved At most it has one optional XML declaration and one document type definition The document may be distributed across many files perhaps on different systems See also document element root element document element Also called the root element the document element is the outermost element in a document contains everything except the document prolog and any comments or processing instructions outside of it See also document root element document instance An actual document that conforms to a general document model See alsodocument DTD document model A template for a document that defines elements and their content models A DTD or a scheme is a document model See also DTD schema downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir DOM document object model A specification that defines the structure of a document as a collection of objects and how the document can be accessed and manipulated A document object model is an API application programming interface which describes how programs actually interpret the structure and contents of a document document prolog A section at the beginning of a document that declares the document to be XML and specifies the version of XML it conforms to for example lt xml version 1 0 gt Additional information about the document can be declared including the document type declaration The document prolog precedes the docu
208. b 3 looks in MathML s content mode Example 3 10 Content encoding in MathML lt xml version 1 0 gt math xmlins http www w3 org 1998 Math MathML gt lt apply gt lt power gt lt apply gt lt plus gt lt apply gt lt times gt en 2 lt cen lt 1 Pas clo lt apply gt C1 gt be 7 ci apply eonmsoce7onm apply lt math gt Why the two modes of MathML One reason is flexibility of authoring But a more important reason is that each lends itself to a different means of processing Presentational encoding is easier to render visually and so is better supported in browsers and such Content encoding because it s more regular and closer to the meaning of the expression is easier to process by calculator type programs With support for MathML in browsers and other programs increasing its popularity is growing For more information read A Gentle Introduction to MathML by Robert Miner and J eff Schaeffer at http www dessci com en support tutorials mathml default htm Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 3 4 Documents Describing Documents Many XML documents contain metadata information about themselves that help search engines to categorize them But not everyone takes advantage of the possibilities of metadata And unless you re using an exhaustive program that spiders through an entire document collection it s difficult to summa
209. b browser for its bul transformer Simply add a line like this to the XML document to tell the browser to transform it lt xml stylesheet type text xsl href path to stylesheet Replace path to stylesheet with a URL for the actual location of the XSLT stylesheet This method is used to transform more complex XML languages into simpler presentational HTML 1 4 5 Formatting for Print Technology pundits have been predicting for a long time the coming of the paperless office All data wou on computer read on monitors and passed around through the network But the truth is people use pa more than ever For reading a long document there is still no substitute for paper Therefore XML has embrace print Formatting for print begins with a transformation Your XML document which is marked up for describin and information says nothing about the appearance It needs to be converted into a presentational forn describes how things should look typefaces colors positions on the page and so on There are many s like Tg X PostScript and PDF The trick is how to get from your XML to one of these formats You could theoretically write a transformation stylesheet to mutate your XML into PostScript but this v nightmares and a head full of gray hairs PostScript is UGLY So are most other presentational formats li RTF and MIF The fact that they are text not binary doesn t make them much easier to understand Ai transformation stylesheet y
210. b ir downloaded from fib ommolkcefab ir lt fo layout master set gt x 1 The page master object with settings for the page s content rectangle gt lt fo simple page master master name the only page type page height 1lin page width 2 8 5in margin top lin margin bottom lin margin left 1 2in margin right 1 21in gt x 1 A body region 20 millimeters below the top of the page s content rectangle gt fo region body margin top 20mm gt A header that is 3 10 inch tall fo region before extent 0 3in gt fo simple page master fo layout master set xsl apply templates lt 7 TOL FOOL lt xsl template gt Note that when you set the margin top of the region body to less than the extent of the region before there s a risk that the header and the region body will overlap Next we have to define the flows There is one static flow for the header and one regular flow for the body In my stylesheet chose to output thepage sequence FO from a template matching the document element First to be defined is the header flow lt xsl template match TEI 2 gt fo page sequence master reference the only page type fo static content flow name xsl region before SIOLDILIODE font family geneva sans serif font size 8pt text align 2 left border bottom solid lpt black lt xsl value of selects reiHeader sourceDesoe lt lo blok clrorstetleo
211. because they follow the line of text They begin and enc within the lines scanning from left to right or right to left if we re reading Arabic Inlines are used to n words or phrases for special formatting from the surrounding text in the block Examples include empha glossary terms and important names Here Is an example of a block with inlines lt para gt lt person gt R Buckminster Fuller lt person gt once said lt quote gt When people learned to do lt emphasis gt more lt emphasis gt with lt emphasis gt less lt emphasis gt it was their lever to industrial success lt quote gt lt para gt The element para is a block containing a whole paragraph of text Inside it are three inline element typ person quote and emphasis The quote element contains elements itself the two emphasis element but is still considered an inline since it begins and ends within the text line of the block There are different reasons to use inlines One is to control how the text formats In this case a formatt will probably replace the quote start and end tags with quotation marks For emphasis elements it migh downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir render the contents in italic underline or bold Another role for inlines is to mark text for special processing Theperson element may have no special treatment by the formatter but could be useful in other ways Marking items as person place defi
212. behavior for an element by making the attribute implicit in the element declaration It is not necessary to declare a namespace for xm1 space This attribute is built into the XML specification and all XML processors should recognize it Some parsers given a DTD for a document will make reasonably smart guesses about which elements should preserve whitespace and which should not Elements that are declared in a DTD to allow mixed content should preserve whitespace since it may be part of the content Elements not declared to allow text should have whitespace dropped since any space in there is only to clarify the markup However you can t always rely on a parser to act correctly so using thexm1 space attribute is the safest option 2 4 5 Trees Elements can be represented graphically as upside down tree like structures The outermost element like the trunk of a tree branches out into smaller elements which in turn branch into other elements until the very innermost content empty elements and character data is reached You can think of the character data as leaves of the tree Figure 2 14 shows the telegram document drawn as a tree Figure 2 14 A document tree downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Colone Rabot sitting Timeslip instructions Ties Se twice a Or Indigo day Rca y Thanks for while I m away and if he starts to m Watching iy He needs to be get cranky
213. below It declares namespaces for XSLT control elements prefix xs1 and implementation specific elements prefixext Finally it specifies the version 1 0 of XSLT in the last attribute lt xsl stylesheet xmins xsl http www w3 org 1999 XSL Transform xmlns ext http www myxslt org extentions extension element prefixes ext version 1 0 gt The namespace represented here as xs1 is used by the transformation processor to determine which elements control the process Any elements or attributes not in that namespace nor the extensions namespace will be interpreted as data to be output in the result tree Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 7 5 Templates XSLT stylesheets are collections of templates Each template associates a condition e g an element in the source tree with a particular attribute with a mixture of output data and instructions These instructions refine and redirect processing extending the simple matching mechanism to give you ful control over the transformation A template does three things First it matches a class of node The match attribute holds an XSLT pattern which much like an XPath expression matches nodes When an XSLT processor is told to apply templates to a particular node the processor runs through all the templates in the stylesheet and tests whether the node matches the template s pattern All the templates that match
214. cBook document can be transformed into HTML for presentation on a browser It s a very powerful technique that we will have fun talking about later 5 1 2 3 Cascading styles Stylesheets can be modularized to mix and match rules This is the source of the term cascading in CSS The idea is that no stylesheet ought to be monolithic Instead you should be able to combine styles from different sources create subsets and override rules in different situations For example you can use a general purpose stylesheet combined with one that fine tunes the style settings for a specific product see Figure 5 4 Figure 5 4 A cascade of stylesheets downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir One reason for doing this is to make it easier to manage a huge set of style rules The fix once see everywhere principle is enhanced when changes to one set of rules are inherited by many stylesheets Cascading rules also make it possible to change the result at any point in the transaction All browsers in fact have a default client side stylesheet that specifies how to render HTML in the absence of any specifications from the server Some browsers such as Mozilla allow you to edit this local stylesheet or user stylesheet so you can customize the appearance to suit your tastes For example if you think most text in pages is hard to read you can increase the default size of fonts and save yourself some eyestrain 5 1 2 4
215. capabilities 7 6 1 Setting the Output Mode A global setting you may wantto include in your stylesheet is the output element It controls how the XSLT engine constructs the result tree by forcing start and end tags handling whitespace in a certain way and so on It is a top level element that should reside outside of any template Three choices are provided XML HTML and text The default output type XML is simple whitespace and predefined entities are handled exactly the same in the result tree as in the input tree so there are no surprises when you look at the output If your result document will be an application of XML place this directive in your stylesheet exelroutput uethode sumlt t s HTML is a special case necessary for older browsers that do not understand some of the new syntax required by XML It is unlikely you will need to use this mode instead of XML for XHTML nevertheless it is here if you need it The exact output conforms to HTML version 4 0 Empty elements will not contain a slash at the end and processing instructions will contain only one questior mark So in this mode the XSLT engine will not generate well formed XML Text mode is useful for generating non XML output For example you may want to dump a documen to plain text with all the tags stripped out Or you may want to output to a format such as troff or TeX In this mode the XSLT engine is required to resolve all character entities rather than keep
216. catch readers attention better if it were enclosed in a border With the border property you can create many kinds of effects from dotted lines enclosing lt block to rules on any side It takes three parameters to define the border you want Thewidth can be an absolute or relative measurement or one of three preset values Chir medium the default CHIC The next parameter is style Eight styles are provided in CSS2 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir solid dashed dotted groove ridge double inset OULSeL The final parameter is color Put all the parameters together in a space separated list in any order Some examples border thin solid green border red groove thick border inset blue 12pt 5 4 4 3 Padding One thing is still missing Recall that this border is just inside the margins putting it right against the text of the block As a result we need some extra space inside the border to keep it from crowding the text The padding property lines the inside of the border with space to compact the text and keer the border from colliding into it The value of this property is a space separated list of between one and four length measurements The application of lengths to sides is the same as it Is with the margin property Let s expand on our previous warning example by giving it a border shown in Figure 5 11 warning display Dilock border Thick solid gray j w
217. cess downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir A popular use of transformations is to change a non presentation XML data file into a format that combines data with presentational information Typically this format will throw away semantic information in favor of device specific and highly presentational descriptions For example elements that distinguish between filenames and emphasized text would be replaced with tags that turn on italic formatting Once you lose the semantic information it is much harder to transform the document back to the original data specific format That is okay because what we get from presentational formats is the ability to render a pleasing view on screen or printed page There are many presentational formats Public domain varieties include the venerable troff which dates back to the first Unix system and TeX which is still popular in universities Adobe s PostScript and PDF and Microsoft s Rich Text Format RTF are also good candidates for presentational formats There are even some XML formats that can be included in this domain XHTML is rather generic and presentational for narrative documents SVG a graphics description language is another format you could transform to from a more semantic language Example 1 6 shows an XSLT stylesheet that changes any telegram document into HTML Notice that XSLT is itself an XML application using namespaces an XML syntax for grouping
218. chapnum gt lt xsl when gt xsl choose lt xsl text gt lt xsl text gt lt xsl value of select title gt To block fo static content 1 REST OF CHAPTER ON EVEN PAGE gt fo static content flow name region other recto after SIOSDIOQE border top solid lpt black padding before 2mm font family myriad verdana sans serif font weight bold font size 8pt text align right lt fo page number gt clrorbBlock lforstatic contents downloaded from fib ommolkcetftab ir downloaded from lib ommolketab ir 1 REGULAR BODY FLOW gt fo flow flow name xsl region body SIOSDIOGE font size l0pt font family garamond palatino serif break before 2 page xsl apply templates select not self title gt e TOs pDlockS lt fo7 low gt lt fo page sequence gt lt xsl template gt lt xsl template match Simplesect partintro sectl sect2 sect3 gt xsl apply templates lt xsl template gt 8 6 4 Simple Blocks The next crop of templates are for more mundane blocks namely heads of chapters tables figures and so on One interestingly named template calledchapnum determines how to label a chapter level element If it is called from the context of a chapter it will just return a number But from insid an appendix the function will return a letter lt xsl template match book title gt lt xsl template match chapter tit
219. character is zero The last point follows the last character in the text node and its index is equal to the length of the string It s important to note that the first point in the first text node of the example above is not equal to the first point of the element para These are two separate points XPath and XPointer use UCS character encoding whereas DOM uses UTF 16 and XML by default is UTF 8 This could cause some confusion when doing string comparisons For example what is one character in an XPath string might be two in a DOM string For more about character encoding seeChapter 9 Inside each container node the point whose index is zero is called thestart point The point with the highest index is the end point A range also has start and end points but they might not come from the same container node 6 4 3 Character Escaping XPointers have somewhat complex character escaping rules This is a side effect of the fact that they can appear in different contexts Inside an XML document for example the well formedness rules apply So characters like and amp must be represented with appropriate character entity references When using xpointers you always should be careful with three characters left and right parentheses and the circumflex Parentheses mark the beginning and end of data inside a location term so any parenthesis that is meant to be data is liable to confuse an XPointer parser The way to escape such a cha
220. ching nodes among the ancestors and their preceding siblings may be considered Finally if you selectany then all previous nodes matching the pattern are counted These options correspond to decreasing order of efficiency in implementation Consider lt xsl template match footnote gt xelctexto xsl text xsl number count footnote from Chapter level any gt exeletext xsl texr lt xsl template gt This rule inserts a bracketed number where the footnote appears The attribute rom chapter downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir causes the numbering to begin at the last chapter Start tag level any ensures that all footnotes are counted regardless of the level at which they appear The purpose of level multiple Is to create multilevel numbers like1 B iii In this example we use number to generate a multilevel section label lt xsl template match section head gt xsl number count section level multiple format I A 1 xsl apply templates template Assuming that sections can be nested three levels deep you will see section labels likerv c 4 and XX A 10 7 6 6 Sorting Elements often must be sorted to make them useful Spreadsheets catalogs and surveys are a few examples of documents that require sorting Imagine a telephone book sorted by three keys last name first name and town The document looks like this telephone book
221. common encodings used in XML documents There are literally hundreds more but they are either beyond the scope of this book or only of esoteric value In case you are interested in researching this topic more will include some resources inAppendix A for you to follow 9 1 5 Character References Although Unicode puts avast range of characters in one place for authors to use many XML editing software packages do not offer a convenient way to access those characters Recognizing that this difficulty could hurt its adoption the designers of XML have included a convenient mechanism for placing Unicode characters in a document Character entity references also called character references that incorporate the character number in their names stand in for those characters and do not need to be declared beforehand There are two forms based on decimal and hexadecimal representations of the code position The decimal character reference uses the form lt n where n is the decimal position of the character in Unicode The hexadecimal variation has the form xNNNN where NNNN is a hexadecimal value for the position of the Unicode character For example the Greek small letter pi can be represented in XML as amp 960 Or aS amp 4x3C0 In general you may find the hexadecimal version to be more useful Unicode specifications always give character code positions in hexadecimal The problem with numerical character references like these is that th
222. content types are important in many areas outside of email General purposeMI ME dispatchers analyze a document as it appears and routes it to the correct media handler For example web browsers rely on HTTP headers to tell them what kind of data is arriving The following HTTP content type field tells us that the incoming resource is text and should be handled as HTML Content Type text html charset ISO 8859 1 The charset portion is optional and actually means character encoding another case of confusing terms This is another mechanism besides XML declarations for specifying a character encoding In XML too there are cases in which MIME is useful For example in linking with XPointers it would be helpful to the XML processor to know in advance what resource is being imported Another example is specifying a stylesheet in a document xml stylesheet type text css href ex2 memo css Here the type attribute is set to a MIME content type for CSS stylesheets As XML rises in prominence as an exchange medium on the Internet the need for media types that identify XML related data grows A recent specification RFC 3023 adds a few new XML related medi types to the mix and a way to extend other media types to include a xml suffix For example you can make the type image svg more descriptive by adding the tag to make it image svg xml A system that recognizes and treats XML data specially will benefit from that extra information
223. createAttribute createEntityReference Generates a new node object createElementNS createAttributeNS DOM2 only Generates a new element or attribute node object with a specified namespace qualifier Crea eDocument Yr raged Creates a container object for a document s subtree getElementsByTagName Returns a NodeList of all elements having a given tag name at any level of the document getElementsByTagNameNS DOM 2 only Returns a NodeList of all elements having a given namespace qualifier and local name The asterisk character matches any element or any namespace allowing you to find all elements in a given namespace getElementById DOM 2 only Returns a reference to the node that has a specified ID attribute importNode DOM2 only Creates a new node that is the copy of a node from another document Acts like a copy to the clipboard operation for importing markup 10 9 1 2 DocumentFragment The DocumentFragment class is used to contain a document fragment Its children are zero or more downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir nodes representing the tops of XML trees This class contrasts withDocument which has at most one child element the document root plus metadata like the document type In this respect DocumentFragment s content is not well formed though it must obey the XML well formed rules in al other respects no illegal characters in text etc No specific me
224. creating a result tree fragment but sometimes you have to use the element content method when more complex calculations such a those involving choices are necessary 7 6 4 Creating Nodes You can create elements and attributes just by typing them out in template rules as we have seen in previous examples Although this method is generally preferable for its simplicity it has its limitations For example you may want to create an attribute with a value that must be determined through a complex process lt xsl template match a gt lt p gt See the lt a gt xsl attribute name href 5http www oreilly com catalog xsl call template name prodname gt lt xsl attribute gt catalog page lt a gt for more information a E lt xsl template gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir In this template the element attribute creates a new attribute node named lt href gt The value of this attribute is the content of the node creating element in this case a URI with some variable text provided by a call template element As have written it here the variable text is impossible to include inside the element so have broken it out in a separate attribute node creation step 7 6 4 1 Elements XSLT provides an element for each node type you would want to create element creates elements Usually you don t need this because you can just type in the element tags In some circumstances
225. cription gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt payment gt lt payment type debit gt lt payee gt Lone Star Cafe lt payee gt lt amount gt 36 86 lt amount gt date 26 6 00 date description category food gt lunch with Greg lt description gt lt payment gt payment type check number 981 gt lt payee gt Wild Oats Market lt payee gt lt amount gt 47 28 lt amount gt lt date gt 29 6 00 lt date gt lt description category food gt groceries lt description gt lt payment gt lt payment type debit gt lt payee gt Barnes and Noble lt payee gt lt amount gt 58 79 lt amount gt date 30 6 00 date description category work gt O Reilly Books lt description gt lt payment gt payment type check number 982 gt lt payee gt Old Man Ferguson lt payee gt lt amount gt 800 00 lt amount gt lt date gt 31 6 00 lt date gt lt description category misc gt a 3 legged antique credenza that once belonged to Alfred Hitchcock lt description gt lt payment gt lt checkbook gt Now we will write an XSLT stylesheet to change this type of document into a nicely formatted HTML page As a further benefit our stylesheet will add up the transactions and print a final balance assuming that the initial balance is zero The first template sets up the HTML page s outermost structure lt xsl template match checkbook gt SEIL
226. d from lib ommolketab ir downloaded from fib ommolkcetab ir mixed content XML elements mixed content entities modeling models area content 2nd documents 2nd modes XSLT rules modification backgrounds fonts modular DTDs modularity RELAX NG stylesheets combining XSLT modularization DTDs modules importing moving DTDs Mozilla 1 4 multimedia standards multiple language support multiple stylesheets Multipurpose Internet Mail Extensions MI ME Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir Team LiB A B C D E F EG H 1 DJ K L M N O IP Q R S ET U V W X named character entities named patterns named templates NamedNodeMap class names classes rules in XML namespaces 2nd nodes RELAX NG XSLT narrative documents 2nd See also documents blocks complex structures DocBook DTDs flow linked objects metadata XHTML nested grammars Netscape Navigator newline characters Node class node set expressions 2nd NodeList class nodes 2nd classes 2nd context current current set points ranges retrieving root searching subtrees testing text tree representation types of values viewing in XML document trees XPath Boolean expressions downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir expressions node set expressions number expressions
227. d within a document that specifies the appearance of a document There are several standards for stylesheets including CSS XSLT and XSL FO SYSTEM identifier A local system dependent identifier for a document DTD or external entity In XML a system identifier must be a URI Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB tag An element name enclosed in angle brackets used to mark up the semantics or structure of a document Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB U Unicode A character set standard that attempts to encompass characters from all the world s major scripts URI uniform resource identifier The W3C s codification of the name and address syntax of present and future objects on the Internet In its basic form a URI consists of a scheme name such aShttp ftp mailto etc followed by a colon and then the path as defined by the scheme that precedes it URI is an umbrella term encompassing URLs and all other uniform resource identifiers URL uniform resource locator The name and address of an existing object accessible over the Internet UTF 8 The UCS Transformation Format for 8 bit platforms UTF 8 is a transformation encoding that converts Unicode character encodings so they can be used on 8 bit based systems Team LiB downloaded from lib ommolketab ir
228. dard way of specifying the presentation of a document by applying formatting rules to elements Cascading refers to how an element is formatted when several rules overlap such as a locally applied rule and a global rule See alsopresentation stylesheet current node The node in which an expression is being evaluated See alsocurrent node set node XSLT current node set The set of selected nodes that provide the immediate context for an expression See also downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir current node node XSLT Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB D declaration A special object that configures the environment of the document It may introduce a new element create an entity or name the type of document Declarations use a special delimiter to keep them apart from elements adding an exclamation mark to the opening angle bracket lt name statement where name is the type of declaration and statement contains the rest of the required information to make a declaration See also markup delimiter Any character or group of characters that separates data or markup The angle brackets in XMI tags lt gt are delimiters CDATA sections have three delimiters lt and See also markup document In XML a document is a complete root element after all external entity references h
229. des and data These objects are typically created by a factory object making it a little easier for programmers who only have to initialize the factory object themselves In DOM every piece of XML the element text comment etc is a node represented by a node object The Node class is extended by more specific classes that represent the types of XML markup including Element Attr attribute ProcessingInstruction Comment EntityReference Text CDATASection and Document These classes are the building blocks of every XML tree in DOM The standard also calls for a couple of classes that serve as containers for nodes convenient for shuttling XML fragments from place to place These classes areNodeList an ordered list of nodes like all the children of an element andNamedNodeMap an unordered set of nodes These objects are frequently required as arguments or given as return values from methods Note that these objects are all live meaning that any changes done to them will immediately affect the nodes in the document itself rather than a copy When naming these classes and their methods DOM merely specifies the outward appearance of an implementation and leaves the internal specifics up to the developer Particulars like memory management data structures and algorithms are not addressed at all as those issues may vary among programming languages and the needs of users This is like describing a key so a locksmith can make a lock that it
230. dient gt Gloppy brand peanut butter lt ingredient gt lt ingredient gt bread lt ingredient gt lt ingredient gt jelly lt ingredient gt lt ingredients gt CIDECEBOLLIONS lt step gt Spread peanut butter on one slice of bread lt step gt lt step gt Spread jelly on the other slice of bread lt step gt step Put bread slices together with peanut butter and jelly touching lt step gt eJJnetructione lt recipe gt A stream generating parser would report these events UJ DOT MEE A 10 11 12 A document start A start tag for the recipe element A start tag for the name element The piece of text peanut butter and jelly sandwich An end tag for the name element A comment with the text add picture of sandwich here A start tag for the ingredients element A start tag for the ingredient element The text Gloppy A reference to the entity trade The text brand peanut butter An end tag for the ingredient element and so on until the final event the end of the document is reached Somewhere between chopping up a stream into tokens and processing the tokens is a layer one might call an event dispatcher It branches the processing depending on the type of token The code that deals with a particular token type is called anevent handler There could be a handler for start tags another for character data and so on A common technique is to create a function or subroutine for each event t
231. document in Example 3 4 To maximize the possibilities for formatting it we should add some structure with aiv elements and use span elements to increase the granularity of inlines Example 5 1 is the improved result Example 5 1 An XHTML document with DI Vs and SPANs lt OL gt lt head gt lt title gt CAT 1 System General Commands Manual lt title gt lt link rel stylesheet type text css href stylel css gt lt head gt Spodyeo lt h1 gt CAT 1 System General Commands Manual lt hl gt div class section lt h2 gt NAME lt h2 gt lt p gt cat concatenate and print files lt p gt lt div gt lt div class section gt lt h2 gt SYNOPSIS lt h2 gt lt p class code gt cat benstuv lt em gt file lt em gt lt p gt lt 7 as div class section gt lt h2 gt DESCRIPTION lt AZ gt o The span class command gt cat lt span gt utility reads files sequentially writing them to the standard output The file operands are processed in command line order A single dash represents the standard input lt p gt eu The options are as follows lt p gt dl dt span class option b span dt gd Implies the span class option n span option but doesn t number blank lines dd lt dt gt lt span class option e span dt lt da gt Implies the lt span class option gt v lt span gt option and displays a dollar sign lt span class symbol gt lt s
232. documents and their parts as nested boxes A big box filled with a million tiny boxes is much harder to work with than a box with a few medium boxes and smaller boxes inside those and so on e Know when to use elements over attributes An element holds content that is part of your document An attribute modifies the behavior of an element The trick is to find a balance between using general elements with attributes to specify purpose and creating an element for every single contingency 4 2 4 3 Modularization There are advantages to splitting a monolithic DTD into smaller components ormodules The first benefit is that a modularized DTD can be easier to maintain for reasons of organization mentioned earlier and because parts can be edited separately or turned off for debugging purposes Also the DTD becomes configurable Modules in separate files can be swapped with others as easily as redefining a single parameter entity Even within the same file they can be marked for inclusion or exclusion XML provides two ways to modularize your DTD The first is to store parts in separate files then import them with external parameter entities The second is to use a syntactic device called a conditional section Both are powerful ways to make a DTD more flexible 4 2 4 4 Importing modules from external sources A DTD does not have to be stored in a single file In fact it often makes sense to store it in multiple files You may wish to borrow f
233. does hav element called div that can be used as a section container however it is not specifically designed as su nor is it used often in HTML documents div is more often used to divide regions for special formattinc stand by my assertion that HTML is essentially a flat structured language 1 XHTML 2 0 is introducing new elements section and h which will fill this gap Now direct your attention to the inlines in the example cc and i The names are abbreviations for presentational terms teletype and italic Right there you know something s wrong HTML has few element types but is meant to be used for many different types of document So the inventors picked elements that are generic and style oriented As a result we re forced to mark up terms the way we war them to look rather than by what they are HTML does supply an inline element called span which can be supplemented with attributes to fit all kin roles For example could have used span class command gt for the cat command and span class citation for the reference to UNIX Style This would allow some flexibility in designing a stylesheet but it s really not using the full power of XML It s just one element being stretched into man different roles Even some of the blocks have been forced into generic roles The paragraph under the head SYNOPSIS isn t really a paragraph is it It s really something different and would prefer to use an element strictl
234. downloaded from fib ommolkcefab ir Team LiB 6 1 Nodes and Trees Remember in Chapter 2 when we talked about trees and XML said that every XML document can be represented graphically with a tree structure The reason that is important will now be revealed Because there Is only one possible tree configuration for any given document there is a unique path from the root or any point inside to any other point XPath simply describes how to climb the tree it a series of steps to arrive at a destination By the way we will be slipping into some tree ish terminology throughout the chapter It s assumed you read the quick introduction to trees in Chapter 2 If you hear me talking about ancestors and siblings and have no idea what that has to do with XML go back and refreshyour vocabulary 6 1 1 Node Types Each step in a path touches a branching or terminal point in the tree called anode In keeping with the arboreal terminology a terminal node one with no descendants is sometimes called aleaf In XPath there are seven different kinds of nodes Root The root of the document is a special kind of node It s not an element as you might think but rather it contains the document element It also contains any comments or processing instructions that surround the document element Element Elements and the root node share a special property among nodes they alone can contain other nodes An element node can contain other elements plus an
235. dy when your amp productname is misplaced and discovered by primitive aliens who might otherwise accidentally injure themselves para entry lt row gt lt row gt lt entry gt lt emphasis gt Real lt emphasis gt Power Switch lt entry gt lt entry gt lt para gt An invisible fingerprint scanning capacitance sensitive on of switch lt para gt lt entry gt lt row gt amp vellip lt row gt lt entry gt The Z Twiddle Switch lt entry gt lt entry gt lt para gt We re not entirely sure what this does Our lab testers have had various results from teleportation to spontaneous liquification emphasis role bold gt Use at your own risk lt emphasis gt lt para gt lt entry gt row tbody eZbumEoupo lt table gt downloaded from fib ommolkcetftab ir downloaded from lib ommolketab ir lt note gt le OEE DOLE LO gt lt para gt A note to arthropods Stop forcing your inflexible appendages to adopt un ergonomic positions Our new claw friendly control template is available lt para gt lt note gt lt sect1 gt secti lt title gt The View Screen lt title gt lt para gt The view screen displays error messages and warnings such as a lt errorcode gt LOW BATT lt errorcode gt low battery message footnote SER NOTE Xd gt lt para gt The advanced model now uses a direct psychic link to the user s visual cortex but it should appear approximately the same as the more pr
236. e CSS2 builds on CSS1 and with few exceptions all stylesheets valid in CSS1 are also valid in CSS2 CSS2 supports media specific stylesheets so authors can tailor the presentation of their documents to visual browsers aural devices printers Braille devices hand held devices etc This specification also supports content positioning downloadable fonts table layout internationalization features automatic counters and numbering and some user interface properties XSL Extensible Stylesheet Language is a stylesheet language for XML W3C Status XSL became a W3C Recommendation in October 2001 The specification is published at http www w3 org TR xsl downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Description XSL is a language for formatting XML documents It consists of an XML vocabulary of formatting objects XSL FO and a language for transforming XML documents into those formatting semantics XSLT An XSL stylesheet specifies the presentation of a class of XML documents by describing how an instance of the class is transformed into an XML document that uses the formatting vocabulary XSLT XSL Transformations is a language for transforming XML documents Status XSLT became a W3C Recommendation in November 1999 The specification is published at http www w3 org TR xslt A working draft of XSLT 2 0 may be found at http www w3 org TR xslt20 Description XSLT is a languag
237. e downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir File Edit View Go Communicator Help Back Reload Home Search Wetse LI amp Bookmarks 4 Location Qi whats Related Members WebMail Connections BizJoumal SmartUpdate Miktplace Income from 21 6 00 until 31 86 00 1 On 21 6 00 987 32 was depostted into pour account by Bad s Sets Expenditures from 21 6 00 until 31 6 00 ranked from highest to lowest 1 0n 31 6 00 vau paid SERO 06 To C Man Ferguson for a 3 legged antique credenzs That once belonged to Alfred Hit hc ack 2 Un 23 86 00 you paid 132 77 to kinat Sports Eguipmen for kendo eauipment 3 Dn 30 6 00 you paid 58 79 to Barres var Males for O Reilly Books 4 On 28 6 00 you paid 47 2B to Wad Cats Marte for groceries 5 On 24 86 00 vou withdrew 40 00 from an ATH for pocket money 6 Dn 25 5 00 you paid 56 686 to Law Sta Cafe for lunch with Greg Balance our balance xs of 351 6 00 is DANGER Deposit money guck 100 joe Jam oe 3 x 7 6 9 Combining Stylesheets There are various reasons to use multiple stylesheets for the same document For instance you may be supporting several documents that share most of the same style but have a few local differences between them Or you might have to combine different namespaces each with its own style set You may want to borrow some styles from a library and override the ones you want to customize XSLT
238. e e blockquote xsl use attribute sets common atts lt xsl value of select gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt blockquote gt lt xsl template gt You can include as many attribute sets as you want by including them in a space separated list 7 6 4 3 Text nodes Creating a text node is as simple as typing in character data to the template However it may not always come out as you expect For example whitespace is stripped from certain places in the template before processing And if you want to output a reserved character such as lt it will be output as the entity reference not the literal character The container element text gives you more control over your character data It preserves all whitespace literally and in my opinion it makes templates easier to read The element has an optional attribute disable output escaping which if set to yes turns off the tendency of the XSLT engine to escape reserved characters in the result tree The following is an example of this lt xsl template match codelisting xsl text disable output escaping yes gt amp lt hey gt lt xsl text gt lt xsl template gt This produces the result lt hey gt 7 6 4 4 Processing instructions and comments Creating processing instructions and comments is a simple task The element processing instruction takes an attribute name and some textual content to create a proc
239. e XSLT processing e g Internet Explorer it s more likely you ll want transformations to be done on the server side where you have more control and can cache results Property sets are finite so no matter how many features are built into a stylesheet language there will always be something lacking some effect you want to achieve but can t When that happens yot should be open to other options such as post processing with custom software InChapter 10 I ll talk about strategies for programming with XML This is the ultimate and most work intensive solution but sometimes there just is no other way to get what you want Unquestionably implementation among clients has been the biggest obstacle The pace of standards development was much faster than actual implementation Browsers either didn t support them or had buggy and incomplete implementations This is quite frustrating for designers who want to support multiple platforms but are stymied by differing behaviors among user agents Not only does behavior vary among vendors but among versions and platforms too Internet Explorer for example behaves very differently on Macintosh than it does on Windows for versions that came out at the same time When wrote the first edition of this book was quite disappointed by the level of support for CSS Any but the most simple example would not work on more than one browser Since then the situation has improved a little Mozilla has much better
240. e a header with a very detailed set of metadata elements and a text body whose structure is reminiscent of DocBook Although the DTD i very large it is modular and can be customized for specific needs The effort has been very successful with tens of thousands of books articles poems and plays now encoded in TEI XML Huge repositories have made these documents available to the public such as the Electronic Text Center http etext lib virginia edu at the University of Virginia Library It holds approximately 70 000 humanities texts in 13 languages The TEI Consortium s web site http www tei c org is brimming with helpful documents and pointers to resources The tutorial TEI P4 Guidelines for Electronic Text Encoding and Interchange is available online at http www tei c org PAX SG html In designing the stylesheet like to start with the page layout This is a very small document that can fit entirely on one page so we only need define one page master Later on in this chapter I ll show you a more complex example that uses a lot of different page masters Below l ve created a page master that defines two regions a header and a body My style is to define this information in an XSLT template matching the root node lt xsl template match gt CTOTTOOD x 1 The root element contains everything in the FO tree downloaded from lib ommolketa
241. e a rule dictating what to do with it and its content The rule can be explicit defined by you or implicit not finding a specific rule the processor falls back on a default one These rules are encoded in an XSLT document using an ingenious mechanism called atemplate which is a sample of a piece of the result document Some blanks need to be filled into the template but otherwise you can see by looking at the template how the future document will look Here is a typical XSLT stylesheet with a couple of templates xsl stylesheet xmlns xsl http www w3 org 1999 XSL Transform version 1 0 gt lt first template how to process a para element gt lt xsl template match para gt lt p gt xsl apply templates dor lt xsl template gt lt second template how to process a note element gt lt xsl template match note gt lt div class note gt SI NOTE lt ho xsl apply templates eg lt xsl template gt lt xsl stylesheet gt The first template tells the XSLT processor what to output when it comes across apara element in the source document The second is a rule fornote elements In each case the template element s contents mirror a piece of the document to be created Note the use of the namespace prefix xs1 in some of the elements This is how the XSLT processor can tell the difference between markup to be obeyed as instructions and markup to be output In other words if there is no
242. e directives at your disposal 7 5 4 1 The apply templates instruction The element apply templates interrupts the current processing in the template and forces the XSLT engine to move on to the children of the current node This enables recursive behavior so that processing can descend through the tree of a document It is calledapply templates because the processor has to find new templates to process the children The first template in Example 7 2 contains an apply templates element lt xsl template match manual gt 6 0 lt head gt lt title gt Instructions Guide lt title gt lt head gt Dodgy gt lt hl gt Instructions Guide lt hl gt xsl apply templates lt body gt lt 7 cil lt xsl template gt When processing this template the XSLT engine would first output the markup starting from the html start tag all the way to the end tag of the h1 element When it gets to the xsl apply templates element it jumps to the children of the current Manual element and processes those with their own templates the attributes type and id then the elements parts 1ist and instructions After all these have been processed the XSLT engine returns to its work on the above template and outputs the end tags forbody and html Suppose that you did not want to handle all the children of a node but just a few You can restrict the set of children to process using the attributeselect It takes an XPath location path as its value giving yo
243. e first declaration of an entity takes precedence over all other declarations of that entity So you can override entity declarations in the DTD by declaring them in the internal subset New elements and attributes can be declared in the internal subset but you may not overrid existing declarations in the DTD Recall that the mechanism for redefining an element or attribute is to use a parameter entity to turn off a conditional section containing the DTD s declaration downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir This example shows some correct uses of the internal subset lt DOCTYPE inventory SYSTEM InventoryReport dtd 1 add a new category attribute to the item element lt ATTLIST item category screw bolt nut REQUIRED gt redefine the general entity companyname gt lt ENTITY companyname Crunchy Biscuits Inc gt x 1 redefine the lt price gt element by redefining the price module parameter entity gt lt ELEMENT price currency amount lt ENTITY price module IGNORE gt x use a different module for figures than what the DTD uses SIENIIIY T1908 SYISLEM moriqe mog gt The attribute list declaration in this internal subset adds the attributecategory to the set of attributes for item As long as the DTD doesn t also declare acategory attribute for item this is Okay The element declaration here clashes with a decla
244. e for transforming XML documents into other XML documents It is designed for use as part of XSL which is a stylesheet language for XML XSL also includes an XML vocabulary for specifying formatting and uses XSLT to describe how the document is transformed into another XML document that uses the formatting vocabulary Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 5 Programming DOM The Document Object Model is a general API for XML parsing W3C Status DOM Level 2 became a W3C Recommendation in November 2000 and is composed of five specifications DOM2 Core Specification http www w3 org TR DOM Level 2 Core DOM2 Views Specification http www w3 org TR DOM Level 2 Views DOM2 Events Specification http www w3 org TR DOM Level 2 Events DOM2 Style Specification http www w3 org TR DOM Level 2 Style DOM 2 Traversal and Range Specification http www w3 org TR DOM Level 2 Traversal Range Work on DOM Level 3 is in progress More information on DOM Level 3 which notably adds XPath and Load and Save support is available athttp www w3 org DOM Description DOM Level 2 is a platform and language neutral interface that allows programs and scripts to dynamically access and update the content and structure of documents The DOM Level 2 Core builds on the DOM Level 1 Core and consists of a set of core interfaces that create and manipulate
245. e it is usually called a stylesheet it is not necessarily used to apply style This is just a term inherited from the original intention of using XSLT to construct XSL FO trees Since XSLT is used for many other purposes it may be better to call it an XSLT script or transformation document but will stick with the convention to avoid confusion The XSLT processor is a state engine That is at any point in time it has a state and there are rules to drive processing forward based on the state The state consists of defined variables plus a setof context nodes the nodes that are next in line for processing The process is recursive meaning that for each node processed there may be children that also need processing In that case the current context node set is temporarily shelved until the recursion has completed The XSLT engine begins by reading in the XSLT stylesheet and caching it as a look up table For each node it processes it will look in the table for the best matching rule to apply The rule specifies what to output to build its part of the result tree and also how to continue processing Starting from the root node the XSLT engine finds rules executes them and continues until there are no more nodes in its context node set to work with At that point processing is complete and the XSLT engine outputs the result document Let us now look at an example Consider the document inExample 7 1 Example 7 1 Instruction guide for a mod
246. e value 200 gt amp Ixscpresreclotiomn lt xs complexType gt lt xs element gt lt Enumerated type male or female gt lt xs element name gender gt lt xs simpleType gt xs restriction base string gt lt xs enumeration value female gt lt xs enumeration value male gt downloaded from fib ommolkceftab ir downloaded from fib ommolkcefab ir Jee e Cee ric ion lt xs simpleType gt lt xs element gt x 1 structure containing the name note the choice element that allows an optional junior OR senior element lt xs element name name gt lt xs complextype gt lt xStall gt lt xs element ref first gt lt xs element ref last gt 7 x3 iall gt xs choice minOccurs 0 gt lt xs element ref junior xs element ref senior lt xs choice gt lt xs complextype gt lt xs element gt lt xs element name junior type emptyElem xs element name senior type emptyElem 1 Defining a type of element that is empty gt xs complexType name emptyElem xs schema Some notes Since XML Schema supports a variety of date formats for character data it makes sense to replace the cumbersome date container and its three child elements with one that takes only text content This simplifies the schema and supporting software for the census application used an attribute maxOccurs to allow an unlimited number of person elements
247. ead for one lookup As the document grows the access time gets longer Storing it in memory isn t much better since searches are not optimized for finding records by unique identifier It s not as bad as doing an exhaustive search through many files but not as good as a true database Dedicated databases are designed to store data in a way that is independent of the size and number of records They are fast but they lack the flexibility and ease of access of XML A data processing program must access the data indirectly through an interface like SQL This can be cumbersome because data is stored in separate rows of a table and it make take several queries to reach the right data point Even worse no two databases work the same way Each has its quirks and refinements that make it difficult or impossible to write universal software without some kind of middleware adapter Storing data as XML versus storing it in a database does not have to be an exclusive choice There is downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir no reason why you can t do both at once One technique have used is to store XML in a database Consider the document in Example 3 3 It contains a number of villain elements each with an id attribute containing a unique identifier Example 3 3 An XML document to put in a database lt villain database gt villain id vl1 gt lt name gt Darth Vader lt name gt lt evil gt 8 lt evil
248. ead only downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 10 9 1 4 1 Properties Here are the properties for the Node class nodeName A property that is defined for elements attributes and entities In the context of elements this property would be the tag s name nodeValue A property defined for attributes text nodes CDATA nodes processing instructions and comments nodeType One of the following types of nodes Element Attr Text CDATASection EntityReference Entity ProcessingInstruction Comment Document DocumentType DocumentFragment OF Notation parentNode A reference to the parent of this node childNodes An ordered list of references to children of this node if any firstChild lastChild References to the first and last of the node s children if any previousSibling nextSibling The node immediately preceding or following this one respectively attributes An unordered list NamedNodeMap of nodes that are attributes of this one if any ownerDocument A reference to the object containing the whole document It s useful when you need to generate a new node namespaceURI DOM 2 only A namespace URI if this node has a namespace prefix otherwise it isnull prefix DOM2 only The namespace prefix associated with this node 10 9 1 4 2 Methods Here are the methods for the Node class insertBefore Inserts a node before a reference child element replaceChild
249. eam LiB 4 5 Schematron Schematron takes a different approach from the schema languages we ve seen so far Instead of being prescriptive as in this element has the following content model it relies instead on a series c Boolean tests Depending on the result of a test the schema will output some predetermined message The tests are based on XPath which is a very granular and exhaustive set of node examination tools Relying on XPath is clever taking much of the complexity out of the schema language XPath which is used in places such as XSLT and some implementations of DOM can scratch an itch that more blunt tools like DTDs can t reach As the creator of Schematron Rick Jelliffe says it s like a feather duster for the furthest corners of a room where the vacuum cleaner DTD cannot reach 4 5 1 Overview The basic structure of a Schematron schema is this schema xmlns http www ascc net xml schematron SPAC CLEN lt rule context XPath Expression gt lt assert test XPath Expression gt message assert report test XPath Expression message lt report gt ade COSL saa lt rule gt more rules lt pattern gt Rx IDEE PACCO ssa schema A pattern in Schematron does not carry the same meaning as patterns in RELAX NG Here it s just a logical grouping of rules If your schema is testing books one pattern may hold rules for chapters while another groups rules for appendixes So think of this as m
250. echnical terms and complex structures like tables lists and sidebars The Wireless Markup Language WML is somewhat like XHTML but specializes in packaging documents for tiny screens on cellular phones We will discuss this narrative style of document in Chapter 3 Modeling In this group are all the technologies developed to create models of documents that formalize c markup language and can be used to test document instances against standard grammars These include DTDs part of the core XML 1 0 recommendation the W3C s XML Schema RELAX NG and Schematron all of which will be covered inChapter 4 Locating and linking Data is only as useful as it is easy to access it That s why there is a slew of protocols available for getting to data deep inside documents XPath provides a language for specifying the path t a piece of data XPointer and XLink use these paths to create a link from one document to another XI nclude imports files into a document The XML Query Language XQuery still in drafts creates an XML interface for non XML data sources essentially turning databases into downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XML documents We will explore XPath and XPointer inChapter 6 Presentation XML isn t very pretty to look at directly If you want to make it presentable you need to use a stylesheet The two most popular are Cascading Style Sheets CSS and theExtensible Style Language XSL T
251. ecommendation in September 2002 and is published at http www w3 org TR xinclude Description XI nclude specifies a processing model and syntax for general purpose inclusion Inclusion is accomplished by merging a number of XML infosets into a single composite infoset Specification of the XML documents infosets to be merged and control over the merging process is expressed in XML friendly syntax elements attributes and URI references Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 3 Addressing and Querying XPath XML Path Language is used for locating XML objects W3C Status XPath became a W3C Recommendation in November 1999 The specification is published at http www w3 org TR xpath XPath 2 0 Working Drafts include the XQuery 1 0 and XPath 2 0 Data Model at http www w3 org TR xpath datamodel XQuery 1 0 and XPath 2 0 Functions and Operators at http www w3 org TR xpath datamodel XQuery 1 0 and XPath 2 0 Formal Semantics at http www w3 org TR xquery semantics and XML Path Language XPath 2 0 at http www w3 org TR xpath20 Description XPath is a language for addressing parts of an XML document designed to be used by both XSLT anc XPointer XPath 2 0 was expanded considerably to add support for W3C XML Schema information anc XQuery XPointer XML Pointer Language is a standard for specifying paths in URI s W3C Status Most of X
252. ed column of content whereas pagination produces discrete regions with breaks in content and vertical margins Pagination has other complexities such as page layout types and line spacing for vertical justification The area model treats visual document structure in a generic way that is compatible with online and print needs HTML frames can be derived easily from abstract structures as can page layouts It can be as complex as you need it to be At the top level of the FO tree is a page layout section which declares page layout master templates These masters can be combined in sequences in a wide variety of ways Content is stored in page sequence objects These are the clay from which the document is sculpted Many layout settings are available to control page related formatting They include hyphenation widow and orphan control columnar layout and so on A special concept is the viewport Aviewport is the physical region in which you can put content In a web browser the dimensions of the window determine the viewport area Since the window can be resized the viewport is variable In print a piece of paper is the viewport This geometry does not usually change except in cases where you rotate the view from portrait to landscape mode The XSL recommendation includes a set of aural properties for FOs This is a radically different medium than print and screen but an important one nonetheless Speech synthesis is a maturing technology a
253. ed from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LIB A B C D E F G H 1 J K L EM N O P IQ R S T U IV W X W3C World Wide Web Consortium web sites for XML information XML Schema 2nd weight fonts well formed XML documents well formedness data integrity whitespace 2nd See also spacing properties schemas XSLT formatting working draft W3C standards process working drafts World Wide Web Consortium See W3C Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E IF G H 1 J K L EM N O P IQ IR S T U IV W X X Smiles XDR XML Data Reduced Xerces parser XHTML narrative documents XLink XML Extensible Markup Language See also documents applying data integrity documents authoring formatting viewing goals of history of markup markup language toolkit multiple language support overview of parsing printing programming standards transformation XML Pointer Language See XPointer XML Schema XML Data Reduced XDR xml lang attributes XPath as API expressions Boolean node set number strings predicates shortcuts XPointer XPointer XML Pointer Language 2nd 3rd character escaping functions points XSL Extensible Style Language XSL Extensible Stylesheet Language XSL FO XSL Formatting Objects areas DocBook format
254. ed text in a page is determined by the relevent page master s specifications Which page master will be used depends on thepage sequence master and which pages have come before 8 4 1 1 Page sequence masters page sequence master Objects contain pieces of the page sequence orsub sequence specifiers The downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir simplest kind is a reference to a single page master represented as asingle page master reference object For example rto layout master set rto page sequence master fo single page master reference master reference pasic lt fo page sequence master gt lt fo simple page master master name basic gt 245 cue lt fo simple page master gt fo layout master set This defines a sequence of exactly one page It is not very useful by itself unless your whole document fits in one page Often you may want to define a standalone sequence to handle a special kind of page layout such as a landscape mode table Another sub sequence specifier is repeatable page master reference It Is like single page master reference except that it can repeat by setting the attribute maximum repeats to a number Or no limit In this example thebasic page master will be applied to all pages in the document rto layout master set lt fo page sequence master gt lt fo repeatable page master reference maximum repeats no limit master reference basic
255. edetermined vocabulary it s possible to invent a markup language as you go along Perhaps in a future telegram want to identify a new kind of thing with an element I v never used before Say wrote to a friend inviting her to a party and enclosed the date in an element called appropriately date Free form XML as like to call it is perfectly legal as long as it s well formed In other words as long as you spell tags correctly use both start tags and end tags and obey all the other minimal rules it s good XML Documents that follow the syntax rules of XML are well formed XML documents This piece of text would fail the test on three counts equation a lt b lt equation gt Can you find all the problems First the start tag is spelled incorrectly because it has two left brackets instead of a left and a right Second there is a left bracket in the content of the element which is illegal Third the end tag of the element is missing a slash This is not well formed XML Any program that parses it should stop at the first error and refuse to have anything more to do with it Well formedness is XML s purity test What does this get us Compatibility It allows you to write a program or a library of routines that know nothing about the incoming data except that it will be well formed XML An XML editor could be used to edit any XML document a browser to view any document and so on Programs are more robust and less complex when
256. eets supply more options for specifying sizes lengths colors margins and other properties usually with the option for flexible relative dimensions Limited reusability Sometimes you want your document to be used in different ways but are limited by the hardwired presentation details Write a document in HTML and it s only good for viewing online You can print it out but the typeface looks big and blocky because it s designed for a computer screen You could cut and paste the content into another program but then you d lose design information or you d carry in some unwanted artifacts Spurious whitespace for example Again the separation of stylesheet from document will help you here You can write as many stylesheets as you want for different purposes see Figure 5 2 In the document you only need to change a simple setting to associate it with a different stylesheet A web server can detect what device is requesting a page and select an appropriate stylesheet The user can alsc make changes to the presentation substituting their own stylesheet or just overriding a few Styles Figure 5 2 Mixing and matching stylesheets for different purposes Stylesheet O yr o jJ O un O Desktop Display XML Document Stylesheet B D E C YY pium f O np O Printed Document Stylesheet C 0 X Lo O J O op CO L Wireless Device To summarize the three principle ways in which stylesheets he
257. efab ir Namespaces are used to separate elements and attributes into different groups W3C Status Namespaces became a Recommendation in January 1999 and the specification is published at http www w3 org TR REC xml names Description XML namespaces provide a simple method for qualifying element and attribute names used in XML documents by associating them with namespaces identified by URI references Namespaces in XML 1 1 Minor update to namespace rules W3C Status Namespaces in XML 1 1 became a Candidate Recommendation in December 2002 and the specification is published athttp www w3 org TR xml names11 Description The 1 1 specification cleans up rules for declaring namespaces by making a provision for undeclaring namespaces making it possible to reduce the number of unused declarations that apply to a given document framework W3C XML Schema The W3C XML Schema language defines object like structures for XML documents W3C Status XML Schema became a W3C Recommendation in May 2001 The recommendation is published in three parts downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XML Schema Part 0 Primer http www w3 org TR xmischema 0 XML Schema Part 1 Structures http www w3 org TR xmlschema 1 XML Schema Part 2 Datatypes http www w3 org TR xmischema 2 Description The XML Schema language is used to define documents in a way that is beyond the ca
258. efficient when separated into tree structures Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 2 9 Entities Entities are placeholders in XML You declare an entity in the document prolog or in a DTD and you can refer to it many times in the document Different types of entities have different uses You can substitute characters that are difficult or impossible to type with character entities You can pull in content that lives outside of your document with external entities And rather than type the same thing over and over again such as boilerplate text you can instead define your own general entities Figure 2 17 shows the different kinds of entities and their roles In the family tree of entity types the two major branches are parameter entities and general entities Parameter entities are used only in DTDs so I ll talk about them later in Chapter 4 This section will focus on the other type general entities Figure 2 17 Entity types wm Lem An entity consists of a name and a value When an XML parser begins to process a document it first reads a series of declarations some of which define entities by associating a name with a value The value is anything from a single character to a file of XML markup As the parser scans the XML document it encounters entity references which are special markers derived from entity names For each entity reference the parser cons
259. efpurpose gt concatenate and print files lt refpurpose gt lt refnamediv gt lt refsynopsisdiv gt csvnopsisscsLt beustuv l lt replaceable gt file lt replaceable gt lt synopsis gt lt refsynopsisdiv gt lt refsect1l gt lt title gt Description lt title gt lt para gt The lt command gt cat lt command gt utility reads files sequentially writing them to the standard output The file operands are processed in command line order A single dash represents the standard input lt para gt downloaded from lib ommolketab ir downloaded from lib eommolketab ir lt para gt The options are as follows lt para gt lt variablelist gt lt varlistentry gt lt term gt lt option gt b lt option gt lt term gt lt listitem gt lt para gt Implies the option n option option but doesn t number blank lines lt para gt lt listitem gt lt varlistentry gt lt varlistentry gt lt term gt lt option gt e lt option gt lt term gt lt listitem gt lt para gt Implies the lt option gt v lt option gt option and displays a dollar si 5 at the end of each line as well lt para gt lt listitem gt varlistentry varlistentry term option n option term lt listitem gt lt para gt Numbers the output lines starting at 1 lt para gt lt listitem gt varlistentry varlistentry term option s option term lt listitem gt lt para gt Squeezes multiple adjacent empty lines
260. eir appearance Instead of angle brackets for delimiters they use the ampersand and semicolon In upcoming sections I ll explain each of theseobjects in more detail Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 2 2 Documents An XML document is a special construct designed to archive data in a way that is most convenient for parsers It has nothing to do with our traditional concept of documents like the Magna Carta orTime magazine although those texts could be stored as XML documents It simply is a way of describing a piece of XML as being whole and intact for parsing It s important to think of the document as alogical entity rather than a physical one In other words don t assume that a document will be contained within a single file on a computer Quite often a document may be spread out across many files and some of these may live on different systems All that is required is that the XML parser reading the document has the ability to assemble the pieces into a coherent whole Later we will talk about mechanisms used in XML for linking discrete physical entities into a complete logical unit As Figure 2 2 shows an XML document has two parts First is thedocument prolog a special section containing metadata The second is an element called thedocument element also called the root element for reasons you will understand when we talk about trees The root element conta
261. eir own encodings in their document prologs After the text declaration the resemblance to normal document prologs ends External parsed entities including DTDs must not contain a document type declaration 4 2 2 Declarations A DTD is a set of rules or declarations Each declaration adds a new element set of attributes entity or notation to the language you are describing DTDs can be combined using parameter entities a technique called modularization You can also add declarations inside the internal subset of the document downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The order of the declarations is important in two situations First if there are redundant entity declarations the first one that appears takes precedence and all others are ignoredl2 This is important to know if you are going to override declarations either in the internal subset or by cascading DTDs Second if parameter entities are used in declarations they must be declared before they are used as references 2 Entity declarations are the only kind of declaration that can appear redundantly without triggering a validity error If an element type is declared more than once it will render the DTD and any documents that use it invalid Declaration syntax is flexible when it comes to whitespace You can add extra space anywhere excep in the string of characters at the beginning that identifies the declaration type For examp
262. el rocket manual type assembly id model rocket gt ato Lieu part label A count 1 gt fuselage left half lt part gt part label B count 1 gt fuselage right half lt part gt lt part label F count 4 gt steering fin lt part gt part label N count 3 gt rocket nozzle lt part gt part label C count 1 gt crew capsule lt part gt lt parts list gt lt I n tructions gt SSLep Glue part ref A and part ref B together to form the fuselage lt step gt SSLOD For each part ref F gt apply glue and insert it into slots in the fuselage lt step gt SOLep downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Affix lt part ref N gt to the fuselage bottom with a small amount of glue lt step gt SSLOL Connect part ref C gt to the top of the fuselage Do not use any glue as it is spring loaded to detach from the fuselage step lt instriu uctions gt lt manual gt Suppose you want to format this document in HTML with an XSLT transformation The following plain English rules describe the process 1 Starting with the manual element set up the shell of the document in this case thehtml element title and metadata 2 For the parts 1ist element create a list of items 3 For each part with a label attribute create a 1i element in the parts list 4 For each part with a ref attribute output some text only the label and name
263. elative terms as percentages of the parent FO s dimensions or in actual units Points picas inches centimeters and ems are supported Combine the value with a unit abbreviation from Table 8 1 Table 8 1 Unit abbreviations Unit Abbreviation Centimeter cm Em em Inch in Millimeter mm Pica 12 pt pc Point 1 72 in pt Pixel px downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Ems and pixels are relative units Their actual length depends on the context An em is the width of c lowercase letter m in the current typeface A pixel is only meaningful in computer displays being the width of a single display element on the screen Dimensions may also be expressed with algebraic expressions using operators for addition multiplication power and modulus Functions for absolute value ceiling min max and rounding ar also available Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 8 4 Formatting Objects Formatting objects FOs are the building blocks of the transformation result tree that drives the formatter They are compact containers of content and style with all the information necessary to generate a presentable formatted document There are two major kinds of FO Flow objects create areas and appear inside flows A flow is a continuous stream of text that may be broken across pages Layou
264. element DTD identifier declarationi declaration a oo oF 00 2 3 2 1 System and public identifiers The DTD identifier supports two methods of identification system specific and public Asystem identifier takes the form shown in Figure 2 5 the keyword SYSTEM 1 followed by a physical address 3 such as filesystem path or URI in quotes 2 Figure 2 5 Form of the system identifier Here is an example with a system identifier It points to a file calledsimple dtd in the local filesystem DOC TIE oc SYSTEM usr local xml dtds simple dtd gt An alternative scheme to system identifiers is the public identifier Unlike a system path or URI that can change anytime an administrator feels like moving things around a public identifier is never supposed t change just aS a person may move from one city to another but her social security number remains th same The problem is that so far not many parsers know what to do with public identifiers and there is single official registry mapping them to physical locations For that reason public identifiers are not considered reliable on their own and must include an emergency backup system identifier Figure 2 6 shows the form of a public identifier It starts with the keywordPuBLIc 1 and follows with e character string 3 in quotes 2 and the backup system identifier 4 also in quotes 2 Figure 2 6 Form of the public identifier downloaded from lib ommolketab ir
265. eloped in the late 1980s It includes ISO 8859 1 Latin 1 the most common character encoding used on Unix systems today Table 9 1 lists encodings in this specification Table 9 1 ISO character encodings Encoding Character set iso 8859 2 Latin 2 Central European characters ISO 8859 4 Latin 4 Baltic languages ISO 8859 5 Cyrillic ISO 8859 6 Arabic ISO 8859 7 Greek ISO 8859 8 Hebrew ISO 8859 9 Latin 5 ISO 8859 14 Celtic ISO 8859 1 is a popular choice for documents because it is contains most European characters and because it is a straight 8 bit mapping it is compatible with a wide range of legacy software If you Suspect that your software is rejecting your document because of the default UTF 8 encoding try setting the encoding to Latin 1 Then if you need to use special symbols or high characters you can insert them with character entity references IANA registered encoding names for ISO Latin 1 include IS0O 8859 1 the preferred MIME name 1atini and 11 A variant of Latin 1 is 150 8859 1 Windows 3 1 Latin 1 This is the encoding used by U S and Western European versions of Microsoft Windows It s almost the same as ISO 8859 1 but adds some useful punctuation in an area reserved for control characters in the ISO character sets This encoding is also known as codepage 1252 but that s not a registered encoding name downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 9 1 4 2
266. ement lt define gt lt grammar gt The combine attribute is necessary to tell the processor how to incorporate the new definition with the previous one imported from block rng Note that for multiply defined patterns of the same name one is allowed to leave out the combine attribute as is the case in the file block rng 4 4 7 4 Overriding imported definitions You can override some definitions that you import by including new ones inside theinclude element Say we have a file report rng defined like this grammar xmlnse http relaxng org ns structure l 0 sotar element name report ref name head ref name body gt element C B ai BP lt define name head gt lt element name title gt lt text gt lt element gt Jdefine define name body lt element name section gt lt oneOrMore gt lt element name para gt lt text gt lt element gt lt oneOrMore gt lt element gt lt define gt lt grammar gt We wish to import this grammar but adjust it slightly Instead of just atitle we want to allow a Subtitle as well Rather than rewrite the whole grammar we can just redefinehead lt grammar xmlns http relaxng org ns structure 1 0 include href report rng gt define name head gt lt element name title gt lt text gt lt element gt CODLIODnAl element name sSubtitle gt lt text gt lt element gt optional define downloaded fr
267. ement with aclass attribute which is supported in HTML and SVG The CSS processor tries to find the best rule or rules for each element In a stylesheet several rules may apply For example p big font size 18pt j p 1 lont ramuilvs Garamond Se9rrit Lont 51xer 122p E Colores Diack font size lO0pt j The first rule matches a p with attribute class big The second matches any p regardless of attributes and the last matches any element at all Suppose the next element to process is ap with the attribute class big All three rules match this element How does CSS decide which properties to apply The solution to this dilemma has two parts The first downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir is that all rules that match are used It s as if the property declarations for all the applicable rules were merged into one set That means all of these properties potentially apply to the element tont s xe 1lopt font family garamond serif LOnL s126 l2pt Color olack fonbt 51x68 IUDLI The second part is that redundant property settings are resolved according to an algorithm As you can see there are three different font size property settings Only one of the settings can be used so the CSS processor has to weed out the worst two using a property clash resolution system As a rule of thumb you can assume that the property from the rule with the most specific selector will w
268. ementing RELAX NG Murata Makoto has demonstrated a RELAX NG implementation which occupies 27K on a cell phone including both the schema and the XML parser At about the same time RELAX was taking shape James Clark of Thai Opensource Software was developing TREX It came out of work on XDuce a typed programming language for manipulating XML markup and data XDuce a contraction of XML and transduce is a transformation language which takes an XML document as input extracts data and outputs another document in XML or another format TREX uses XDuce s type system and adds various features into an XML based language XDuce appeared in March 2000 followed by TREX in January 2001 Like RELAX TREX uses a very clear and flexible language that is easy to learn read and implement Definitions of elements and attributes are interchangeable greatly simplifying the syntax It has full support for namespaces mixed content and unordered content things that are missing from or very difficult to achieve with DTDs Like RELAX it uses the W3C XML Schema datatype set reducing the learning curve further RELAX NG new generation combines the best features from both RELAX and TREX in one XML based schema language First announced in May 2001 an OASIS Technical Committee headed by James Clark and Murata Makoto oversees its development It was approved as a Draft International Standard by the ISO IEC 4 1 2 4 Schematron Also worth noting is Schema
269. ements and attributes can apply to any composition of objects and properties J ust as a book breaks down into chapters sections blocks and inlines many abstract ideas can be deconstructed into discrete and hierarchical components Vector graphics for example are compose of a finite set of shapes with associated properties You can represent each shape as an element and use attributes to hammer down the details SVG Is a good example of how to represent objects as elements Take a gander at the simple SVG document in Example 3 7 Here we have three different shapes represented by as many elements a common rectangle an ordinary circle and an exciting polygon Attributes in each element customize the shape setting color and spatial dimensions Example 3 7 An SVG document lt xml version 1 0 gt svg lt desc gt Three shapes lt desc gt rect fill green x lcm y 1cm width 3cm height 3cm gt circle fill red cx 3cm cy 2cm r 4cm gt epolvgon xll blus porlnts 110 1600 50 200 100 290 7 Ec dem Vector graphics are scalable meaning you can stretch the image vertically or horizontally without an loss of sharpness The image processor just recalculates the coordinates for you leaving you to concentrate on higher concepts like composition color and grouping SVG adds other benefits too Being an XML application it can be tested for well formedness can be edited in any generic XML editor and is easy to w
270. endation defines three levels of conformance It says that thebasic level includes the set of formatting objects and properties needed to support a minimum level of pagination or aural rendering Extended adds to that everything else in the standard except shorthand properties which collect a group of properties in one assignment likeborder in CSS Complete conformance has all of that plus shorthands This division does not frequently work in the real world As an example page oriented formatters usually do not have any support for aural speech synthesis formatting so even the official basic conformance is rare Most users are probably interested in using XSL for one medium anyway so it i more useful in my opinion to think of conformance within each medium For example does a formatter correctly produce a page layout from the formatting objects in the print medium Often developers leave out features that are difficult to implement and that they think will not be in high demand Bidirectional support needed for scripts such as Hebrew or Chinese is not present in most formatters Arbortext s formatter does not support mixed language hyphenation FOP has numerous issues with tables such as requiring fixed widths of columns In time many of these features will be incorporated but it will depend on demand and developer time The XSL FO recommendation has left out some important features that may be added in future versions For example index
271. endation that goes up on the W3C s web site must endure a long tortuous process of proposals and revisions before it s finally ratified by the organization s Advisory Committee A recommendation beginsas a project or activity when somebody sends the W3C Director a formal proposal called a briefing package If approved the activity gets its own working group with a charter to start development work The group quickly nails down details such as filling leadership positions creating the meeting schedule and setting up necessary mailing lists and web pages At regular intervals the group issues reports of its progress posted to a publicly accessible web page Such a working draft does not necessarily represent a finished work or consensus among the members but is rather a progress report on the project People in the community are welcome to review it and make comments Developers start to implement parts of the proposed technology to test it out finding problems in the process Software vendors press for more features All this feedback is important to ensure work is going in the right direction and nothing important has been left out particularly when the last call working draft is out The draft then becomes a candidate recommendation At this stage the working group members are satisfied that the ideas are essentially sound and no major changes will be needed Experts will continue to weigh in with their insights mostly addressing det
272. endered in small caps Only when the text has been rendered will you know the last word to be styled this way XSL provides a different strategy for this case The formatting objectinitial property set applies properties to the first line of a block only This example defines a paragraph with an indented first line lt xsl template match para class init gt lt fo block space after lem fo initial property set space before 2em xsl apply templates eJTorDlodks lt xsl template gt 8 4 4 3 Graphics XSL allows one to import external resources into a document and one important kind is a graphic Ar external graphic is an inline object in XSL to allow it to flow along with the rest of the text This woul be convenient if you were using a special icon that could not be represented in Unicode downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The external graphic FO Is an empty element that marks the place in text where the formatter will insert a picture Its src attribute identifies the source of the graphic typically a filename For example this XSL FO markup contains text with an embedded graphic lt fo block space after 2em gt The alchemist picked up a bottle and wrote a strange symbol on the label It looked like this fo external graphic src images blarf eps It made me think of a swarm of snakes fo block Very often you will want to insert a graphic into a documen
273. enough What if a required field of information is missing Or someone has consistently misspelled an element name Or a date was entered in the wrong format These are things only a validating parser can detect e A schema is portable and efficient Writing a program to test a document is an option but it may not be the best one Software can be platform dependent difficult to install and bulky to transfer A schema however is compact and optimized for one purpose validation It s easy to hand someone a schema and you know it has to work for them because its syntax is governed by a standard specification And since many schemas are based on XML they can be edited in XML editors and tested by well formedness checkers e A schema is extensible Schemas are designed to support modularity If you want to maintain a set of similar languages or versions of them they can share common components For example DTDs allow you to declare general entities for special characters or frequently used text They may be so useful that you want to export them to other languages Using a schema also has some drawbacks e A schema reduces flexibility The expressiveness of schemas varies considerably and each standard tends to have its flaws For example DTDs are notorious for their incompatibility with namespaces They are also inefficient at specifying a content model that contains required children that may appear in any order While other schema languages
274. ent bcb graphic CDATA 3 characters Starting element bcb prize namespace http www grubblythings com number of attributes O0 CDATA 12 characters ending element bcb prize CDATA 1 characters ending element bcb breakfast cereal box All done There were 4 elements There you have it Living up to its name SAX is uncomplicated and wonderfully easy to use It does not try to do too much instead offloading the work on your handler program It works best when the processing of a document follows the order of elements and only one pass through it is sufficient One common task by event processors is to assemble tree structures which brings us to the next topic the tree processing API known as DOM Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 9 DOM DOM is a recommendation by the World Wide Web Consortium W3C Designed to be a language neutral interface to an in memory representation of an XML document versions of DOM are available in Java ECMAscript L2l Perl and other languages 2 A standards friendly language patterned after J avaScript While SAX defines an interface of handler methods the DOM specification calls for a number of classes each with an interface of methods that affect a particular type of XML markup Thus every object instance manages a portion of the document tree providing accessor methods to add remove or modify no
275. ents gt IBNIITY block group author blockquote codelisting downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Ws lt ENTITY inline group acronym Citation command emphasis filename firstterm literal lt The document element lt ELEMENT doc title block group section t SIATILISI xoc Coomsmon stL5 lt Section to break up the document gt lt ELEMENT section title block group section gt lt ATTLIST section common atts lt place to put the author s name gt lt ELEMENT author PCDATA gt lt ATTLIST author common atts 1 region of quoted text gt lt ELEMENT blockquote parat gt lt ATTLIST blockquote common atts lt qormel ocodelisting adds title gt lt ELEMENT example title codelisting gt lt ATTLIST example tcommon atts gt lt formal picture adds title gt downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir lt ELEMENT figure title graphic lt ATTLIST figure common atts l cut of 1low note gt lt ELEMENT footnote parat gt lt ATTLIST footnote common atts lt DIOLHfe gt lt ELEMENT graphic EMPTY gt lt ATTLIST graphic fileref CDATA REQUIRED toommnonmdLi5ss lt sequence of items gt lt ELEMENT list term listitem gt lt ATTLIST list type numbered bulleted def
276. eoe TELEGRAM File Edt Types Links Views Style Special Afimbutes Annotations Help Telegram Io Sarah Bellum Fram Colonel Timeslip Subi Robot sitting instructions 1 anks f r watching my robot pal Wile lm away AG needs to be recharged Mice s Gay and if he stars to get cranky give him a quart of oil I ll be back soon after l ve tracked down mal evil Mastermind P S5 Your homework for this week is to prove Newton s theory of gravitatio 4 Ws Text X hl div body html Document 1 4 3 Parsing If you re going to be using XML from error prone sources such as human authors you will probably wan parser preferably with good error reporting in your XML toolkit XML s strict rules protect programs fro unpredictable input that can cause them to crash or produce strange results So you need to make sure data is clean and syntactically correct Before talk about these tools let me first explain how parsing w little theoretical grounding you ll be in good shape for understanding the need for parsers and knowing them Every program that works with XML first has to parse it Parsing Is a process where XML text is collected down into separate manageable parts As Figure 1 10shows there are several levels At the lowest lev characters in the input stream Certain characters are special like gt and amp They tell the parser whe reading a tag character data or some other markup symbol Figure 1 1
277. er 3mm text align 2 justify xsl apply templates Fio blonk lt xsl template gt lt xsl template match programlisting screen gt STOSDOLOOK space after 5mm font family monoco monospace font size 8pt wrap option no wrap xsl apply templates TOtD lock lt xsl template gt lt xsl template match remark gt 109 LOCK margin left 2em margin right 2em space after l1em downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir color blue font weight 2 bold xsl apply templates for block lt xsl template gt lt Container of graphic and caption Normally lt fo external graphic gt is treated as an inline so we have to put it inside a block lt xsl template match figure gt SIO DIOOS text align center width 4in height 2 3in border solid lpt black background color silver lt fo external graphic gt xsl attribute name src gt lt xsl value of select graphic fileref gt xsl attribute fo external graphic Tro blodgk IOS space before 4mm xsl apply templates select title gt lt Totb lock lt xsl template gt lt xsl template match example xsl apply templates lt xsl template gt lt xsl template match sidebar gt SITO DLOCRK background color silver padding l1em margin 2em xsl apply templates lt iorblock lt xsl template gt lt xsl template match note
278. er general entities Nevertheless it s useful to make the distinction because large groups of such entities have been declared in DTI modules that you can use in your document An example is 180 8879 a standardized set of named character entities including Latin Greek Nordic and Cyrillic scripts math symbols and various other useful characters found in European documents 2 5 2 Mixed Content Entities Entity values aren t limited to a single character of course The more general mixed content entities have values of unlimited length and can include markup as well as text These entities fall into two categories internal and external For internal entities the replacement text is defined in the entity declaration for external entities it is located in another file 2 5 2 1 Internal entities Internal mixed content entities are most often used to stand in for oft repeated phrases names and boilerplate text Not only is an entity reference easier to type than a long piece of text but it also improves accuracy and maintainability since you only have to change an entity once for the effect to appear everywhere The following example proves this point lt xml version 1 0 gt lt DOCTYPE press release SYSTEM http www dtdland org dtds reports dtd C IEBNIITY bobeo BopD s Boll Bazaar InG gt J gt lt press release gt title amp bobco Earnings Report for Q3 title lt par gt The earnings report for amp bobco
279. er specification You do this by setting a datatypeLibrary attribute like so lt element name font size lt data type integer datatypeLibrary http www w3 org 2001 XMLSchema datatypes element This will associate the datatype definitions from the W3C Schema specification with your schema The datatypes you can use depend on the implementation of your RELAX NG validating parser It isn t so convenient to put thedatatypeLibrary attribute in every data element The good news is it can be inherited from any ancestor in the schema Here we declare it once in an element declaration and all the data descriptors inside call from that library lt element name rectangle xmlns http relaxng org ns structure 1 0 datatypeLibrary http www w3 org 2001 XMLSchema datatypes gt lt element name width gt lt data type double gt lt element gt lt element name height gt lt data type double gt lt element gt lt element gt 4 4 2 1 String and token Both string and token match arbitrary strings of legal XML character data The difference is that token normalizes whitespace and string keeps whitespace as is They correspond to the datatypes value and fixed respectively 4 4 2 2 Parameters Some datatypes allow you to specify a parameter to further restrict the pattern This is expressed with a param element as a child of the data element For example the element below restricts its content to a string of
280. ere are four directional variants of the form padding side Where side iS before after start Or end Padding properties may be expressed with relative percentage or absolute settings with units Percentages are calculated in relation to the current block s region downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir In XSL FO the term margin has been renamed space as in space before It follows the same scheme as above with padding replaced with space The names of directions have changed from CSS Instead of top and left we have the more abstract before and start This nomenclature is a little confusing but it is necessary to overcome the bias of Western scripts that go left to right and top to bottom In Western style documents before after start and end mean top bottom left and right respectively The formatter takes properties like space after as a rigid constraint This limits its flexibility and consequently can result in some ugly formatting For example two paragraphs in a row will be separated by sum of their space after and space before properties It would be better if you could request an optimal space and also require a minimum and possibly maximum space to give the formatter some room to optimize As it happens each of the space properties can specify minimum optimum and maximum values Each is a compound property able to express these different values by extending
281. ere we use achoice element to provide two cases one with an icon attribute and another with an icon element The two are mutually exclusive lt element name alert xmlns http relaxng org ns structure 1 0 choice lt attribute name icon gt lt value gt bomb lt value gt lt value gt exclamation mark lt value gt lt value gt frown face lt value gt lt Jattribute gt lt element name icon gt lt value gt bomb lt value gt lt value gt exclamation mark lt value gt lt value gt frown face lt value gt element downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt choice gt lt element name body gt lt text gt lt element gt lt element gt Another difference with element declarations is that there is a shorthand form in which the lack of any content information defaults to text So for example this declaration lt element name emphasis gt lt attribute name style gt lt element gt 1S equivalent to this element name emphasis gt lt attribute name style gt lt text gt lt attribute gt lt element gt This interchangeability between element and attribute declarations makes the schema language much simpler and more elegant 4 4 4 Namespaces RELAX NG is fully namespace aware You can include namespaces in any name attribute using the xmlns attribute lt element name poem xmlns http relaxng org ns structure 1 0
282. erty List Class Value F Honl Cichonary Pk AID AlernsUseMainDevice Humber gt 1 v Devices Dictionary y 2 alue pairs F InpulDevices Dictionary valu il Y AppleDBDMAAudioDMAEngine 0 Dictionary y 3 k oy value pairs 0 000000 b DeviceLevels Array 7 2 Ordered objects Level Number 0 500000 F uiputOsvites Dictionary y 1 key value pair y AppieDEDMAAudioDMAEngine 0 Dictionary 3 key valu Ir Balance Number 0 000000 gt DeviceLevels Array 2 0rdere Level Number 1 000000 3 1 2 Records A database typically stores information in records packages of data that follow the same pattern as dictionaries There are lots of records each with the same set of data fields sometimes accessed by a unique identifier For example a personnel database would have a record for each employee Example 3 1 is a simple record style XML document used for expense tracking Example 3 1 A checkbook document lt xml version 1 0 gt lt checkbook balance start 2460 62 gt lt title gt expenses january 2002 lt title gt lt debit category clothes gt lt amount gt 31 19 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 3 lt day gt lt date gt lt payto gt Walking Store lt payto gt lt description gt shoes lt description gt lt debit gt deposit category sSalary gt lt amount gt 1549 58 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 7
283. es design by Edie Freedman The cover image is a 19th century engraving from the Dover Pictorial Archive Emma Colby produced the cover layout with QuarkXPress 4 1 using Adobe s ITC Garamond font David Futato designed the interior layout This book was converted by Andrew Savikas to FrameMaker 5 5 6 with a format conversion tool created by Erik T Ray Jason McIntosh Neil Walls and Mike Sierra that uses Perl and XML technologies The text font is Linotype Birka the heading fon is Adobe Myriad Condensed and the code font is LucasFont s TheSans Mono Condensed The illustrations that appear in the book were produced by Robert Romano and Jessamyn Read using Macromedia FreeHand 9 and Adobe Photoshop 6 The tip and warning icons were drawn by Christopher Bing This colophon was written by Nicole Arigo The online edition of this book was created by the Safari production group John Chodacki Becki Maisch and Madeleine Newell using a set of Frame to XML conversion and cleanup tools written anc maintained by Erik Ray Benn Salter John Chodacki and J eff Liggett Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB A B C D E F G H 1 DJ K L M EN O P Q R IST T U V W X Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LIB A B C ID E IF G IH 1 J K L EM EN O P IQ R
284. es from the command line argument list ARGV and feed them to the parser The eval statement catches any parse errors which we detect in the following die statement The parser puts helpful error messages in e to indicate what may have confused the parser If all goes well the parser will return a reference to the top of the DOM tree specifically an XML LibXML Document object he map proc to elems Is a yet to be written subroutine that will apply a procedure also not yet written to nodes in the DOM tree This is where the real work will take place in the program It makes changes directly to the object tree so all we have to do is print it out as text with the toString method Now let us dig into the map proc to elems routine The purpose of this function is to map a procedure to every element in the document sub map proc to elems my Sproc SnodeRef Q my SnodeType nodeRef nodeType if SnodeType SnodeTypes document map proc to elems proc SnodeRef gt getDocumentElement elsif nodeType SnodeTypes element amp Sproc SnodeRef foreach my childNodeRef nodeRef getChildnodes map proc to elems Sproc SchildNodeRef j You start it with the document node or any element and it will visit every element in that subtree recursing on the children and their children and so on Testing the node s type allows us to make sur we don t try to apply the procedure to anythi
285. es them into object trees XPath s advantage Is that it is has a very rich language for specifying nodes giving the developer a lot of control and flexibility The parsers libxml and MSXML are two that come with XPath interfaces 10 10 2 JDOM Despite the name JDOM isnot merely a Java implementation of DOM Rather it is an alternative to SAX and DOM that is described by its developers as lightweight and fast optimized for the Java programmer It doesn t actually replace other parsers but uses them to build object representation of documents with an interface that is easy to manipulate It is designed to integrate with SAX and DOM supplying a simple and useful interface layer on top The proponents of J DOM say it is needed to reduce the complexity of the factory based specifications for SAX and DOM For that reason the J DOM specification itself is defined with classes and not interfaces In addition to substituting its own new API J DOM includes the fabulousXPath API 10 10 3 Hybrids If streams and trees are the two extremes on a spectrum of XML processing techniques then the middle ground is home to solutions we might callhybrids They combine the best of both worlds low resource overhead of streams with the convenience of a tree structure by switching between the twc modes as necessary The idea Is if you are only interested in working with a small slice of a document and can safely ignore the rest then you only need to work
286. essing instruction lt xsl template match marker gt xsl processing instruction name formatter gt pagenumber lt xsl value of select page gt lt J XSL processing instruction lt xsl template gt This rule creates the following output lt formatter pagenumber 1 gt You can create a comment with the element comment with no attributes lt xsl template match comment gt lt xsl comment gt lt xsl value of select gt lt xsl comment gt lt xsl template gt To create the processing instruction or content of a comment you have to specify either plain text or an element such as value of that becomes text Any other kind of specification produces an error downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 7 6 5 Numeric Text Although value of can output any numeric value as a string it does not offer any special formatting for numbers You are stuck with decimals and that s it For more options you should move up to the more flexible number instruction With this element you can output numbers as Roman numerals with zeros prepended or as letters It also has a built in facility for counting nodes Returning to the table of contents example here is how you could create one withnumber lt xsl template match book gt qxSl tlOr eacn Selecp captor xsl number value position format I gt lt xsl value of select title gt ixsl tor each lt xsl template gt
287. eturn Table 6 4 Location path examples Path Matches quotelist child node Al the quotation elements plus the XML comment quotelist quotation Al the quotation elements Gigs All the quotation elements comment following sibling Gstyle id q1 parent The first quotation element TO ace pam 7 The document element id qi1 ancestor or self The document element and the first quotation element Nothing The first step does match the third quotation element but the next step invalidates it because it s looking for an element of type aphorism In a context where you don t know what type the element is this is a good way to test it The style attribute of the last quotation element id os Sef soporte processing instruction following source The source elements from the last two quotation elements Note that the id step will only work on attributes that have been declared to be typerp in a DTD It is this declaration that tells a validating parser to require an attribute to have a unique value If the axis and node type aren t sufficient to narrow down the selection you can use one or more predicates A predicate is a Boolean expression enclosed within square brackets Every node that passes this test in addition to the node test and axis specifier is included in the final node set Nodes that fail the test the predicate evaluates to
288. ext gt lt element gt lt oneOrMore gt lt externalRef href section rng lt oneOrMore gt lt element gt 4 4 7 2 Nested grammars One consequence of external referencing is that grammars effectively contain other grammars To prevent name clashes each grammar has its own scope for named patterns The named patterns in a parent are not automatically available to its child grammars Instead ref will only reference a definition from inside the current grammar To get around that limitation you can useparentRef It functions like ref but looks for definitions in the grammar one level up For example consider this case where two grammars reference each other am defining one element para as a paragraph that can include footnotes The footnote element contains some number of paras They are stored in files para rng and footnote respectively and shown in Examples Example 4 8 and Example 4 9 Example 4 8 para rng grammar xmlns http relaxng org ns structure 1 0 SStarLs element name para ZerolrMore gt lt choice gt ref name para content gt lt externalRef name footnote rng gt lt choice gt lt zeroOrMore gt lt element gt lt 7 SLATE define name para content gt lt text gt lt define gt lt grammar gt Example 4 9 footnote rng downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt grammar xmlns http relaxng org ns structure 1 0
289. ey are hard to remember You have to keep looking them up in a table cluttering your workspace and generally going mad in the process A better idea might be to use named entity references such as those defined in ISO 8879 This specification defines a few hundred useful entity declarations divided by knowledge area into a handful of files For each character there is a declaration for a general entity with an intuitive name Here are a few of the defined characters Description Unicode character Entity name E Latin small letter a with breve accent Uc 0103 abreve E Planck constant over two pl U 210F planck Yen sign U 00A5 yen downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir To use named entity references in your document you need to obtain the entity declarations and either import them through the internal subset of your document or import them into your DTD got a set when downloaded DocBook XML from the OASIS web site thanks to DocBookmaintainer Norm Walsh for creating an XML version of ISO 8879 Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 9 2 MIME and Media Types The Multipurpose Internet Mail Extensions MIME standard is a means of specifying media types such as images program data audio files and text Described in Internet Engineering Task Force IETF Request for Comme
290. f the Oracle database downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir DocBook the Definitive Guide Norman Walsh and Leonard Muellner O Reilly amp Associates DocBook is a popular and flexible markup language for technical documentation with versions for SGML and XML This book has an exhaustive glossary style format describing every element in detail It also has lots of practical information for getting started using XML and stylesheets XML Schema Eric van der Vlist O Reilly amp Associates Explores W3C XML Schema in depth using many examples to illustrate usage Definitive XML Schema Patricia Walmsley Prentice Hall A thorough explanation of the W3C XML Schema specification and usage RELAX NG Eric van der Vlist O Reilly amp Associates A thorough explanation of RELAX NG including both theory and practice Learning XSLT Mike Fitzgerald O Reilly amp Associates A carefully paced introduction to XSLT development Beginning XSLT Jeni Tennison Wrox Press A tutorial for XSLT focusing on simple and largely HTML based examples XSLT Doug Tidwell O Reilly amp Associates A guide to XSLT development from the basics to advanced features XSLT Programmer s Reference 2nd Edition Michael Kay Wrox Press A reference guide for XSLT development including techniques and best practice Definitive XSLT G Ken Holman Prentice Hall A tutorial and reference for XSLT development
291. false are not Table 6 5 shows some examples downloaded from lib ommolketab ir downloaded from lib ommolketab ir Table 6 5 XPath predicates Path Matches The text element in the third quotation element This is an example of an equality test where the string value of the attribute is matched against another string You can also test numerical and Boolean values Jg 6obtatlonDbeidetgst ext All the quotation elements but the third which doesn t have a source element Here the presence of a child element source IS evaluated if at least one node matching it is found the value of the test is true otherwise false quotation source The third quotation element not is true if there are no source elements id g2 i Loan e queen The source element with the content Samurai Chant sibling source Th mes The text element in the last quotation element Jetrerson 7 Lext Nothing The two predicates are evaluated as a Booleanand source Thomas function Both have to be true or the path fails Since there is Jefferson Gid q7 no element matching both these tests we are left with nothing quotation not source The last quotation element The position function equals the position of the most recent step among eligible candidates The function 1ast is equal to the total number of candidates in this case 5 lfeauobatrionlposition J 192 Al quotation elements
292. ficing richness of expression XML s enthusiastic acceptance by the Internet community has opened the door for many sister standards XML s new playmates include stylesheets for display and transformation strong methods for linking resources tools for data manipulation and querying error checking and structure enforcement tools and a plethora of development environments As a result of these new applications XML is assured a long and fruitful career as the structured information toolkit of choice Of course XML is still young and many of its siblings aren t quite out of the playpen yet Many XML specifications are mere speculation about how best to solve problems Nevertheless it s always good to get into the game as early as possible rather than be taken by surprise later If you re at all involved in information management or web development then you need to know about XML This book is intended to give you a birds eye view of the XML landscape that is now taking shape To get the most out of this book you should have some familiarity with structured markup such as HTML or TgX and with World Wide Web concepts such as hypertext linking and data representation You don t need to be a developer to understand XML concepts however We ll concentrate on the theory and practice of document authoring without going into much detail about writing applications or acquiring software tools The intricacies of programming for XML are left to other books
293. fied ideographic system often called CJK for the initials of each language their number was reduced to the point where it was practical tc add them to Unicode This is often cited as one of the critical flaws of Unicode Although it is fairly comprehensive in including the most used glyphs the way it combines different systems together makes it very inconvenient for constructing a Unicode font or to divide it into useful contiguous subsets An ideograph found in both Chinese and Japanese should really be represented as two different characters each keeping with the styling of the uniquely Chinese or Japanese characters Furthermore even though over 20 000 Han ideographs found a place in Unicode this is still just a fraction of the total There are still 60 000 that didn t make the cut Meanwhile ISO had also been working to develop a multilingual character set Called theUniversal Multiple Octet Coded Character Set UCS or ISO IEC 10646 1 it was based on a 31 bit character providing for over 2 billion characters That is certainly enough to hold all the glyphs and symbols the human race has developed since a person first got the urge to scribble Quickly realizing the redundancy of their projects the Unicode Consortium and ISO got together to figure out how to pool their work UCS being the larger of the two simply made Unicode a subset Today both groups publish independent specifications but they are totally compatible Some termin
294. finition per elementl amp 6 This is how DTDs can be mapped directly into RELAX NG schema This kind of backward compatibility is important since most people are still using DTDs So this is a good way to upgrade to RELAX NG lt grammar xmlns http relaxng org ns structure 1 0 SOLEIL Selemenr nsgsme report gt per fene Litle gt ref name authorname gt zeroOrMore ref name paragraph gt lt zeroOrMore gt lt element gt lt Jotart define name title gt lt element name title gt text lt element gt lt define gt lt define name authorname gt lt element name authorname gt lt text gt lt element gt lt derine gt lt define name paragraph gt element zame paragrapn s text lt element gt lt define gt lt grammar gt 4 4 6 1 Recursive definitions Recursive definitions are allowed as long as the ref is enclosed inside an element This pattern describes a section element that can contain subsections arbitrarily deep grammar xmlns http relaxng org ns structure 1 0 lt start gt lt element name report gt lt element name title gt lt text gt lt element gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt zeroOrMore gt lt ref name paragraph gt lt zeroOrMore gt lt zeroOrMore gt ref name section gt lt zeroOrMore gt lt element gt lt start gt lt define
295. fo inline lt xsl template gt lt xsl stylesheet gt After running the telegram example through FOP with this stylesheet Figure 1 12is the result FOP outp default but other formats will be available soon There is work right now to add MI Fand PostScript as fo Figure 1 12 A PDF document generated by FOP downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir TELEGRAM To Sarah Bellum From Colonel Timeslip Subj Robot sitting instructions Thanka for watching my robot pal zonky while I m away He needa to be recharged twice day and if he Starts to get eranky give him a quart of oil I ll be back soon after I ve tracked down that evil mastermind 1 4 6 Programming When all else fails you can writea program Parsers are the front line for any program that works with XML There are several strategies available d how you want to use the XML The push technique where data drives your program is like a one way The parser reads the XML and calls on your program to handle each new item in the stream hence the i processing Though fast and efficient stream processing is limited by the fact that the parser can t stop to retrieve information from earlier in the stream If you need to access information out of order you he in memory The pull technique allows the program to access parts of the document in any order The parser typica document and stores it in a data structure The structure
296. follow that Parsers can assemble this kind of stream very quickly and efficiently thanks to XML s parser friendly design Other formats often require some look ahead or complex lookup tables before processing car begin For example SGML does not have a rule requiring nonempty elements to have an end tag To know when an element ends requires sophisticated reasoning by the parser making code more complex slowing down processing speed and increasing memory usage You might wonder why an XML stream does not package up complete elements for processing The reason is that XML is hierarchical Elements are nested so it is not possible to separate them into discrete packages in a stream In fact it would resemble the tree method handing out exactly one element the root of the document assembled into a single data structure The event model of processing is quite simple There are only a few event types to keep track of including element tags character data comments processing instructions and the boundaries of the document itself Let us look an example of how a parser might slice up a document into an XML even stream Consider the data file in Example 10 1 Example 10 1 A simple XML document with lots of markup types recipe downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt name gt peanut butter and jelly sandwich lt name gt 1 add picture of sandwich here gt ingredients lt ingre
297. form of attributes An attribute is a name value pair You can use it to add a unique label to an element place it in a category add a Boolean flag or otherwise associate some short string of data InChapter 1 used an attribute in the telegram element to set a priority level One reason to use attributes is if you want to distinguish between elements of the same name You don t always want to create a new element for every situation so an attribute can add a little more granularity in differentiating between elements In narrative applications like DocBook or HTML it s common to see attributes like class and role used for this purpose For example lt message class tip gt When making crop circles push down lt emphasis gt gently lt emphasis gt on the stalks to avoid breaking them lt message gt lt message class warning gt Farmers don t like finding people in their fields at night so be emphasis role bold gt very quiet emphasis when making crop circles lt message gt The class attribute might be used by a stylesheet to specify a special typeface or color It might format the message class warning gt with a thick border and an icon containing an exclamation point while the message class tip gets an icon of a light bulb and a thin border The emphasis elements are distinguished in whether they have an attribute at all The second does and its purpose is to override the default style whatever that may be Ano
298. from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 2 4 Elements Elements are the building blocksof XML dividing a document into a hierarchy of regions each serving a specific purpose Some elements are containers holding text or elements Others are empty marking a place for some special processing such as importing a media object In this section l II describe the rules for how to construct elements 2 4 1 Syntax Figure 2 9 shows the syntax for a container element It begins with a start tag consisting of an angle bracket 1 followed by a name 2 The start tag may contain some attributes 3 separated by whitespace and it ends with a closing angle bracket 4 After the start tag is the element s content and then an end tag The end tag consists of an opening angle bracket and a slash 5 the element s name again 2 and a closing bracket 4 The name in the end tag must match the one in the start tag exactly Figure 2 9 Container element syntax An empty element is very similar as seen inFigure 2 10 It starts with an angle bracket delimiter 1 and contains a name 2 and a number of attributes 3 It is closed with a slash and a closing angle bracket 4 It has no content so there is no need for an end tag Figure 2 10 Empty element syntax An attribute defines a property of the element t associates a name with a value which is a string of character data The syntax shown in Figure 2
299. from lib ommolketab ir downloaded from fib ommolkcefab ir defined in the specification but it is likely most implementers will just extend them using the types ir the W3C Schema recommendation so no worries there By itself Schematron is not nearly as useful as the other validation tools we saw in this chapter One could do some simple tests with XPath but it has no support for regular expressions to match elements or character data and its dependence on a flat set of rules makes schema clunky and hard to develop However when used in conjunction with other validation tools Schematron can really Shine The real win with Schematron writes XML expert Jeni Tennison is when you use it in tandem with another schema language particularly W3C XML Schema There is no way that you Should use it for a standalone schema but to test co occurrence constraints once the initial validatior is done with W3C XML Schema or RELAX NG it s a godsend There was a time when all we had to work with were DTDs With time more and more XML tools become available and we should all be thankful for the tireless efforts of many developers It s wortt taking time to become familiar with different schema types in order to findone that will fit your needs best Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 5 Presentation Part CSS As the Web exploded in popularity in the mid
300. fset substring after A substring of the string argument starting at the end of the first string to match occurrence of the string to match and ending at the end of string normalize space string substring before A substring of the string argument starting at the beginning of string string to match and ending at the beginning of the first occurrence of the stringto match The string With all characters in the string characters to match replaced with their counterpart characters in the string characters replace with Suppose the first argument is the string happy days are here again the second argument is ah and the third string is oH The returned result will be the string Hoppy doys ore Here ogoin translate only works on a per character basis so you can not replace arbitrary strings with it translate string characters to match characters replace with Some functions operate on strings and return numeric or Boolean values These are listed inTable 6 14 Table 6 14 Functions that operate on strings Function Returns containsi String sub True if the substring sub occurs within the string otherwise false string length string The number of characters inside string starts with string sub True if the string begins with the substring sub otherwise false Team LiB downloaded from lib ommolketab ir downloaded from fib om
301. fulltime and parttime Setting the attribute to anything else would result in a validation error Example 4 2 shows the complete DTD Example 4 2 The CensusML DTD ipee Census Markup Language use census record as the document element lt ELEMENT census record date address persont gt lt ATTLIST census record taker CDATA REQUIRED gt lt date the info was collected lt ELEMENT date year month day lt ELEMENT year PCDATA gt lt ELEMENT month PCDATA gt lt ELEMENT day PCDATA gt 1 address information lt ELEMENT address street city county country postalcode gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT street PCDATA city PCDATA gt county PCDATA gt country PCDATA gt postalcode PCDATA gt unit PCDATA gt shige ep gt lt person information lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT lt ELEMENT person name name first age PCDATA gt gender PCDATA gt first PCDATA gt last PCDATA gt Junior EMPTYS senior EMPTY gt age last gender gt Junior senior gt lt ATTLIST po employed person ID fulltimel parttime REQULRED TMPLIED gt 4 2 4 Tips for Designing and Customizing DTDs DTD design and cons
302. fy a syntax method and delimit the downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir data inside The data for an xpointer scheme is an XPath expression or a shorthand form of one There is no need to quote the XPath expression because the parentheses are sufficient to mark the start and end It is possible to chain together xpointers They will be evaluated in order until one is successful For example xpoidter sd flooby xbointer 8id flooby l Here the two xpointers semantically mean the same thing but the first case may fail for an XPointer processor that does not implementid properly This could happen if the processor requires a DTD to tell it which attributes are of typerp but no DTD is given When the first expression returns an error processing shunts over to the next xpointer as a fallback Besides xpointer two other schemes are available xmlns and element The purpose of the xmlns scheme is to update the current evaluation environment with a new namespace declaration Here an xmlns declaration sets up a namespace prefix which is used in the xpointer that follows it xmlns foo http www hasenpfeffer org xpointer foo thingy It may seem odd but the xmlns scheme returns an error status that forces processing to proceed on to the next part of the xpointer using the definition of the oo namespace prefix The element scheme provides a syntactic shortcut It represents the nth chi
303. g way to specify a DTD is to give asystem identifier This is a plain ordinary URL or filesystem path 1 4 4 Transformation The act of changing XML from oneform to another is called transformation This is a very powerful techr employed in such processes as print formatting and conversion to HTML Although most often used to ac presentation to a document it can be used to alter a document for special purposes For example you c transformation to generate a table of contents construct an excerpt or tabulate a column of numbers Transformation requires two things the source document and a transformation stylesheet The styleshe for how to cook the XML and arrive at a desired result The oven in this metaphor is a transformation reads the stylesheet and input document and outputs a result document Several languages have been transformations The Document Style Semantics and Specification Language DSSSL uses the program language Lisp to describe transformations functionally However because DSSSL is rather complex and work with a simpler language emerged the very popular XSLT XSLT didn t start off as a general purpose transformation language A few years ago there was a projec W3C led by James Clark to develop a high quality style description language The Extensible Style Lani quickly evolved into two components The first XSLT concentrated on transforming any XML instance ir presentational format The other component of XSL X
304. g Documents If the ultimate purpose of your XML is to give someone something to look at then you may be intereste out some document viewers You ve already seen examples of editors displaying XML documents You c XML in web browsers too Of course all web browsers support XHTML But Internet Explorer can handle formed XML Since version 5 0 on Macintosh and 5 1 on Windows Internet Explorer has had the ability to read and di has a built in validating XML parser If you specify a DTD in the document IE will check it for validity If errors it will tell you so and highlight the affected areas Viewing a document in IE looks like Figure 1 8 Figure 1 8 Internet Explorer s XML outline view downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir You may have noticed that the outline view in IE looks a lot like the outline view in Morphon XMLEdit It same way The whole document is the root of a tree with branches for elements Click on one of the mi and it will collapse the element hiding all of its contents The icon will become a plus symbol which you to open up the element again It s a very useful tool for navigating a document quickly For displaying formatted documents on computer monitors the best technology is CSS CSS has a rich s attributes for setting colors typefaces rules and margins How much of the CSS standard is implement varies considerably across browsers There are three separate recommendations w
305. g element may contain a whole bunch of elements which in turn contain other elements and so on down to the data This creates an unambiguous hierarchical structure that preserves all kinds of ancillary information sequence ownership position description association An XMLdocument consists of one outermost element that contains all the other elements plus some optional administrative information at the top Example 1 1 is a typical XML document containing a short telegram Take a moment to dissect it with your eyes and then we ll walk through it together Example 1 1 An XML document lt xml version 1 0 gt lt DOCTYPE telegram SYSTEM xml resources dtds telegram dtd telegram pri important gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt to gt Sarah Bellum lt to gt lt from gt Colonel Timeslip lt from gt esubject Robot srtbing instructions sub ecto graphic fileref figs me eps lt message gt Thanks for watching my robot pal lt name gt Zonky lt name gt while I m away He needs to be recharged lt emphasis gt twice a day emphasis and if he starts to get cranky give him a quart of oil I ll be back soon after I ve tracked down that evil mastermind villain Dr Indigo Riceway lt villain gt lt message gt lt telegram gt Can you tell the difference between the markup and the data The markup symbols are delineated by angle brackets lt gt to
306. g our efforts to understand is the interchangeability of incompatible terms Sometimes a character encoding is called a set as in the MIME standard which is incorrect and misleading In this section will try to explain the terms and concepts clearly and describe some of the commor character encodings in use by XML authors 9 1 1 Specifying an Encoding If you choose to experiment with the character encoding for your document you will need to specify it in the XML declaration For example lt xml version 1 0 encoding encoding name gt encoding name ls a registered string corresponding to a formal character encoding No distinction is made between uppercase and lowercase letters but spaces are disallowed use hyphens instead Some examples are UTF 16 ISO 8859 1 and Shift JIS A comprehensive list of encoding names is maintained by the Internet Assigned Numbers Authority LANA available on the Web at http www iana org assignments character sets Many of these encoding names have aliases The aliases for US ASCII includeASCII US ASCII and IS0646 US If you do not explicitly state otherwise the parser will assume your encoding is UTF 8 unless it can determine the encoding another way Sometimes a file will contain abyte order mark BOM a hidden piece of information in the file inserted by software that generated it The XML processor can use a BOM to determine which character encoding to use such as UTF 16 Every XML p
307. general it just seems easier to write schemas in RELAX NG than in W3C Schema The syntax is very clear with elements like zeroOrMore for specifying optional repeating content Declarations can contain other declarations leading to a more natural representation of a document s structure Consider the simple schema in Example 4 7 which models a document type for logging work activity It s easy to read this schema and understand the structure of a typical document Example 4 7 A simple RELAX NG schema lt element name worklog xmlns http relaxng org ns structure 1 0 xmlns ann http relaxng org ns compatibility annotations 1 0 lt ann documentation gt A document for logging work activity broken down into days and further into tasks ann documentation zeroOrMore element name day gt attribute name date gt text attribute lt zeroOrMore gt lt element name task gt element name description gt lt text gt lt element gt lt element name time start gt lt text gt lt element gt lt element name time end gt lt text gt lt element gt lt element gt lt zeroOrMore gt lt element gt lt zeroOrMore gt lt element gt The same thing would look like this as a DTD lt ELEMENT worklog day gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt ELEMENT day task gt lt ELEMENT task description time start time end gt
308. generation is still rather primitive In the meantime vendors are addinc their own extensions using XML namespaces Some examples of this are the ox outline extensions in FOP to generate PDF bookmarks and rx page index In XEP to help create page numbers in indexes The formatter like to use for XSL FO is the free and open source FOP It has pretty decent print oriented support and outputs to PDF MIF PostScript and PCL The formatter is written in Java and its install package includes Apache s XML parser Xerces and XSLT engine Xalan which you can download from http xml apache org 4 The FOP download includes the parser and XSLT classes in one package It also contains a shell script fop that runs Java and supplies the arguments to the formatter 1 You do not have to use Xerces and Xalan You can import XSL FO documents from any source even those you create by hand downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Below is an example of FOP as invoked from the command line The argument xs1 db xs1 gives the name of the XSLT stylesheet The next argument xml chapl xml supplies the source file name The third paf chapl pdf tells which format to output PDF and what to call the output file c Top xel dD X6l xml Ghspl onnh pur Ga3apl por INFO FOP 0 20 4 INFO building formatting object tree INFO 1 INFO 2 INFO 3 INFO 44 INFO 45 INFO 46 INFO Parsing
309. get when you re working for the common good Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Appendix B A Taxonomy of Standards The extensibility of XML is clearly demonstrated when you consider all the standards and specifications that have blossomed from the basic XML idea This appendix is a handy reference to various XML related activities Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 1 Markup and Structure XML 1 0 Extensible Markup Language consists of basic rules for markup W3C Status XML 1 0 second edition became a Recommendation in October 2000 You can read the specification at http www w3 org TR REC xml Description XML is a subset of SGML that is designed to be served received and processed on the Web in the way that is now possible with HTML XML has the advantages of easy implementation and compatibility with both SGML and HTML XML 1 1 Update to XML for changes to Unicode W3C Status XML 1 1 became a Candidate Recommendation in October 2002 You can read the specification at http www w3 org TR xml11 Description XML updates the character tables and whitespace rules of XML 1 0 to reflect changes to the Unicode specification since XML 1 0 became a Recommendation Namespaces in XML downloaded from lib ommolketab ir downloaded from fib ommolkc
310. gion after region name region first verso after extent 0 5in gt lt fo simple page master gt es Odd numbered first page of a chapter fo simple page master master name chapter first recto page height 9in page width 7in margin left l1in downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir margin right lin margan tope 0D 5in margin bottom 0 4in to region body indtogin rop9 2 91 margin bottom 0 6in re lt fo region before region name region first recto before extent lin T fo region after region name region first recto after extent 0 5in f gt lt fo simple page master gt i ra Even numbered page of a chapter not including the first fo simple page master master name chapter other verso page height 9in page width 7in margin left 1in margin right lin margin top 0 5in margin bottom 0 4in fto region body margin bottom 0 6in gt lt fo region after region name region other verso after extent 0 5in cS lt fo simple page master gt Odd numbered first page of a chapter other than the first gt lt fo simple page master master name chapter other recto page height 9 in page width 2 7in margin left lin margin right lin margin top 0 5in margin bottom 0 4in to region body margin bottom 0 61in E fo region after region name 2 region other recto afte
311. give robot pal recharged him a quart of oil I ll be back soon after I ve tracked down that evil mastermind Since every XML document has only one possible tree the diagram acts like a fingerprint uniquely identifying the document It s this unambiguous structure that makes XML so useful in containing data The arboreal metaphor is also useful in thinking about how you would move through a document Documents are parsed from beginning to end naturally which happens to correspond to a means of traversing a tree called depth first searching You start at the root then move down the first branch to an element take the first branch from there and so on to the leaves Then you backtrack to the last fork and take the next branch as shown inFigure 2 15 Figure 2 15 Depth first search Let me give you some terminology about XML trees Every point in a tree be it an element text or something else is called a node This borrows from graph theory in mathematics where a tree is a particular type of graph directed non cyclic Any branch of the tree can be snapped off and though of as a tree too just as you can plant the branch of a willow tree to make a new willow treel31 Branches of trees are often called subtrees or just trees Collections of trees are appropriately called groves 3 Which is why you should never make fenceposts out of willow wood An XML tree or subtree or subsubtree or subsubsubtree must adhere to the rules
312. glyphs and images a formatted document is completely described by an area tree A formatting object tree produces an area tree the way an architectural model leads to a final set of blueprints Strictly speaking there is not a one to one mapping between formatting objects and areas An FO can create zero or more areas and each area is usually produced by a single FO There are exceptions however as in the case of ligatures which are single glyphs created through the contribution of two or more character objects Associated with an area Is a collection of details that completely describe its geometry and rendering These traits as they are called are derived either directly from formatting object properties or indirectly as a result of calculations involving other traits These traits are the final precise data that drive the rendering process in the formatter Areas are divided into two types block and inline Blocks and inlines have been described thoroughly in previous chapters and they behave essentially the same here An area may have block area children or inline area children but never both One common subtype of block areas is theline area the children of which are all inline areas for example a traditional paragraph A subtype ofinline area is the glyph area a leaf in the area tree containing a single glyph image as its content The area model of XSL is strongly reminiscent of the CSS box model In fact areas are a superset of C
313. gt lt intelligence gt 9 lt intelligence gt cCrashion se fashion fila villain id 2 v3 lt name gt Doctor Evil lt name gt lt evil gt 6 lt evil gt lt intelligence gt 6 lt intelligence gt efashion gt 8 lt Tashion gt lt 7 villain villain id v4 gt lt name gt Scorpius lt name gt lt evil gt 9 lt evil gt lt intelligence gt 9 lt intelligence gt rtashion 4 fashrone lt villain gt villain database You want to be able to access avillain by id attribute As an XML document this access would be slow If the record is near the bottom the XML processor needs to read through most of the document before it gets there With thousands ofvillain elements that search could take a very long time Now let us create a database with a table that matches the following schema will use SQL data types Field Data type id varchar 8 content text You can store the information from Example 3 3 in the database Each villain element will be a row in the table we just created Get the id from the attribute in villain and put the rest of the element in the content field Here is what the table would look like id content v1 villain name Darth Vader lt name gt lt evil gt 8 lt evil gt lt intelligence gt 9 lt intelligence gt lt fashion gt 5 lt fashion gt lt villain gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir id content
314. gt nntil x5S1 tee 5 cxslsvealu oft s l cpe chllad s iasEQ date t lt xsl text gt ranked from highest to lowest lt xsl text gt h3 xsl apply templates select payment gt xsl sort data type number order descending select amount gt xsl apply templates h3 Balanceec h5 p xsl text Your balance as of xsl text xsl value of selects child last date xsl text is xsl text CELO lt xsl choose gt lt xsl when test sum payment amount gt sum deposit amount gt lt font color red gt ne lLe bere gt lt xeltitext lt xsl value of select sum deposit amount sum payment amount ront lt xsl when gt lt xsl otherwise gt lt font color blue gt exelrtesrobelxelttexto lt xsl value of select sum deposit amount sum payment amount lt font gt lt xsl otherwise gt lt xsl choose gt cleri or xsl if test sum payment amount sum deposit amount p lt font color red gt lt xsl text gt DANGER Deposit money quick lt xsl text gt e Done lt p gt S XBITAT lt body gt lt hem lt xsl template gt downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir lt xsl template match payment type atm gt e lt xsl value of select position gt xsl text On lt xsl text gt lt xsl value of select date gt lt xsl text gt you withdrew lt
315. he best although there are so many out there today that could not hope to list them all Table 10 1 Some popular XML parsers Name Language APIs Web Site C Perl via XML Parser module Python via xml parsers expat XP Java Low level stream parser http www jclark com xml xp DTD validation SAX minimal DOM2 core need gdome2 library for the API XPath Relax NG XML Schemas data types DTD validation SAX2 core extension DOM2 core events traversal DOM3 experimental core Xerces Native Interface XNI XML Schema structures and data types Java APIs for XML Parsing J AXP DTD validation SAX2 core extension DOM2 core events traversal DOM3 partial core Xerces Native Interface XNI XML Schema structures and data types Expat Low level stream parser http www jclark com xml expat html C Perl via XML LibXML module Xerces2 Java Xerces downloaded from lib ommolketab ir libxml2 http xmlsoft org http xml apache org Java C Perl via XML Xerces module http xml apache org downloaded from lib ommolketab ir Name Language APIs Web Site DID validation DOM DOM SAX XSLT XML Schema http java sun com xml jaxp XPath JDOM an alternative to SAX and DOM DTD validation SAX DOM XSLT XML htt
316. he former is very simple and fine for most online documents The latter is highly detailed and better for print quality documents CSS is the topic ofChapter 5 We will take two chapters to talk about XSL Chapter 7 and Chapter 8 Media Not all data is meant to be read The Scalable Vector Graphics language SVG creates images and animations The Synchronized Multimedia Integration Language SMIL scripts graphic sound and text events in a timeline based multimedia presentation VoiceML describes how to turn text into speech and script interactions with humans Science Scientific applications have been early adopters of XML TheChemical Markup Language CML represents molecules in XML while MathML builds equations Software turns instances of these markup languages into the nicely rendered visual representations that scientists are accustomed to viewing Resource description With so many documents now online we need ways to sort through them all to find just the information we need Resource description is a way of summarizing and showing relationships between documents The Resource Description Framework RDF is a language for describing resources Communication XML is an excellent way for different systems to communicate with each other Interhost system calls are being standardized through applications like XML RPC SOAP WSDL and UDDI XML Signatures ensures security in identification by encoding unique verifiable signatures for
317. height 3in page width 4in margin top 0 5in margin bollom 0 5in ma rgin lert 0 5in margin rzight 0 5in fo region body lt fo simple page master gt fo layout master set fo page sequence master reference the only page type lt fo flow flow name xsl region body lt fo block font family helvetica sans serif font size 24pt text align center padding 0 25in gt lt fo block font weight bold font size 10pt space after lem Hello world lt fo block gt lt fo block padding 0 25in border solid lpt black gt I am lt fo inline font style italic gt so lt fo inline gt clever lt fo block gt Jfo sblock SCIOTLILIONS lt fo page sequence gt lrosfooto I mport this into an XSL formatter and it willgenerate output shown in Figure 8 1 Figure 8 2 The message formatted downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 8 3 The Area Model In XSL all the positioning shaping and spacing of elements on the page takes place inside ofareas An area is an abstract framework used to represent a piece of the formatted document It contains all the geometric and stylistic information needed to position and render its children correctly Areas are nested leading to the concept of an area tree From the root node all the way down to the area containing
318. height and font size adjustment downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Whereas font size determines the size of characters being displayed the line height property affects the total height of thefont plus the whitespace above it If the line height is greater than the font size the difference is made up by adding space evenly to the top and bottom of each line This makes the block look either looser or more condensed In the following example we have specified single space double space and one and one half space between lines paral line height 1 para2 line height 2 Len para3 line height Fonts with the same point size can look bigger or smaller depending on various characteristics summarily referred to as the eye of the font Chief among these is the x height orex In Latin read European fonts ex is the height of a lowercase x Other fonts use different criteria but it s always fraction of the font size or em As a result some fonts appear bigger than others For the obsessive designer there is a way around this problem The ont size adjust property can be used to tweak the sizes of fonts in the ont family property The aspect value is the ratio of the x height to the font size If you provide the aspect value of your desired font expressed as a decima fraction as the value of font size adjust the browser can adjust substitute fonts to have the same apparent
319. hen that we call it the document element It is also sometimes called the root element Inside you ll see more elements with start tags and end tags following a similar pattern There is one exception here the empty tag graphic which represents an empty element Rather than containing data this element references some other information that should be used in its place in this case a graphic to be displayed Empty elements do not mark boundaries around text and other elements the way container elements do but they still may convey positional information For example you might place the graphic inside a mixed content element such as themessage element in the example to place the graphic at that position in the text Every element that contains data has to have both a start tag and an end tag or the empty form used for graphic It s okay to use a start tag immediately followed by an end tag for an empty element the empty tag is effectively an abbreviation of that The names in start and end tags have to match exactly even down to the case of the letters XML is very picky about details like this This pickiness ensures that the structure is unambiguous and the data Is airtight If start tags or end tags were optional the computer or even a human reader wouldn t know where one element ended and another began causing problems with parsing downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir From this e
320. heoad or even attribute is one such test Others include bl1ank or not blank and page position 8 4 1 2 Page masters A page master definesthe content rectangle for a page and how the rectangle is divided into regions The one page master object in XSL version 1 0 issimple page master its name suggests that other page master types will be added in future versions of XSL Itsmaster name attribute is a handle for page sequence masters to reference Other attributes include space settings for defining the page s content rectangle For example lt fo simple page master master name title page page height 1lin page width 2 8 5in margin rtops lin margin bottome lin margin left 1 2in margin right 1 2in gt X fo simple page master This FO declares a page master type whose name Istitle page Its height and width are 11 inches and 8 5 inches respectively The content rectangle is positioned inside that area one inch from top and bottom and 1 2 inches from the left and right sides After defining the content rectangle the page master s other task is to outline the regions for content in the page simple page master allows you to divide a page into as many as five different areas called body region before region after region start region and end region In the European writing mode Ir tb these correspond to the page structures typically called body header footer left sidebar and right sidebar Figure 8 6 shows how these reg
321. higher level to address than just the symbols on the page Different languages may use the same characters If a document is encoded with UTF 8 how can yol know if it is speaking Vietnamese or Italian You may wonder why it matters if software should handle all documents the same way no matter what the language The push for globalization is not a dream shared by everybody Sure we all want equal access to resources but we would also like to keep our uniqueness intact So many developers would love a way to know in advance what language a reader prefers to use and have some automatic means to serve that preference XML and many related standards have included some devices to allow special handling based on language You can use labels to create variations on a document and to customize its appearance and behavior will describe a few of the important mechanisms in this section 9 3 1 The xml lang Attribute and Language Codes XML defines the attribute xml lang as a language label for any element There is no official action that an XML processor must take when encountering this attribute but we can imagine some future applications For example search engines could be designed to pay attention to the language of a document and use it to categorize its entries The search interface could then provide a menu for languages to include or exclude in a search Another use forxm1 1ang might be to combine several versions of a text in one document each
322. html modularization XHTML 1 1 module based XHTML which became a Recommendation in May 2001 is published at http www w3 org TR xhtml11 A subset of XHTML 1 1 XHTML Basic became a W3C Recommendation in December 2000 and is published athttp www w3 org TR xhtml basic Finally work on XHTML 2 0 has started and working drafts are available at Description XHTML 1 0 is a reformulation of HTML 4 as an XML 1 0 application The specification defines three DTDs corresponding to the ones defined by HTML 4 The semantics of the elements and their attributes are defined in the W3C Recommendation for HTML 4 and provide the foundation for future extensibility of XHTML Compatibility with existing HTML user agents is possible by following a small set of guidelines XHTML 1 1 reformulates HTML as a set of modules and XHTML Basic creates a subset of XHTML for use on smaller devices XHTML 2 0 is now under development and represents the first major changes to the HTML vocabulary since HTML 4 0 HTML Hypertext Markup Language is the markup language for World Wide Web documents W3C Status HTML 4 01 is the latest version of the W3C Recommendation dated December 1999 The specification is published athttp www w3 org TR html401 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Description In addition to the text multimedia and hyperlink features of previous versions HTML 4 supports more multimedia options
323. ib eommolketab ir lt document element lt xs element name census record lt xs complexType gt xs sequence lt xs element ref date gt lt xs element ref address gt lt xs element ref person maxOccurs unbounded gt lt xs sequence gt xs attribute ref taker gt lt xs complexType gt lt xs element gt lt Number identifying the census taker 1 9999 gt xs attribute name taker gt lt xs simpleType gt SXSIESSUELODLALOD Dase i1nLeger s exes maimninelusrve value xs maxlInclusive value 9999 gt xetpestrlocLromn lt xs simpleType gt lt xs attribute gt lt l Structure containing date informati n gt lt this is a simplification over the previous definition using gt lt three subelements gt lt xs element name date type date gt lt structure containing address information gt lt xs element name address gt lt xs complexType gt 14 td lt xs element ref street gt lt xs element ref city gt lt xs element ref county gt lt xs element ref country gt lt xs element ref postalcode gt e xe alle lt xs complexType gt lt xs element gt lt Retelenent namee srreer tvpse string xarelement hame city tvupes string xe sel ement names county types striug lt xs element name country type string 1l postalcode element uses format 123ABC gt lt xs element
324. ibing mathematical notation and capturing its structure and content The goal of MathML is to enable mathematics to be served received and processed on the Web just as HTML has done for text Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Glossary Iv O 2 is nr ji m im jo IO W gt Im Io Is IC IH W gt lt Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB amp absolute location term A term that completely identifies the location of a resource via XPointer A unique ID attribute assigned to an element can be used as an absolute location term See alsorelative location term XPath XPointer activity The work being done to produce a standard in some area of interest See alsostandards body actuation How a link in a document is triggered For example a link to an imported graphic automatically includes a graphic in the document and a link to a URL resource requires a signal from a human application This word has different meanings in different contexts In the context of XML an application is usually a specific markup language based on XML rules DocBook is one example of an XML application In the more general context of computer software an application is a high level program for users such as a web browser word processor or spreadsheet manipulator In other words it s an a
325. ice such as a printer or display terminal image gif is a popular image subtype on the Web audio Sound data requiring an audio output device such as a speaker to reproduce audio wav IS one common example video Animated graphical data requiring a viewing device such as the movie formatvideo mpeg application Some undetermined kind of data It may be a binary format or else requiring some processing to be useful A good example is application PostScript which looks like dense program code until sent to a printer Uninterpreted binary data is labeledapplication octet stream a grab bag for unknown types multipart More of a meta type really it packages up a group of possibly unrelated resources Subtypes like multipart mixed and multipart parallel describe how to present the resources e g positioned together on a screen downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir message Another meta type that packages resources In this case the resources all pertain to a single message object presumably adding up to a single communicative package You can see that MIME tackles a huge problem in attempting to label every conceivable kind of data that could be transmitted over a network It works well because of a well publicized registry of medie types maintained by the Internet Assigned Numbers Authority IANA You can see the latest list at http www iana org assignments media types index html MI ME
326. id diner gt lt title gt Sam s Diner lt title gt lt para gt A huge truck passed by eating up four whole lanes with its girth The whole back section was a glitzy passenger compartment trimmed in chrome and neon The roof sprouted a giant image of a hamburger with rlashing lights and the words Sam s Scruvi Soul Snax chac AS Xt sped past at foolhardy speed I saw a bevy of cars roped to the back swerving back and forth lt para gt lt para gt Included among these were lt para gt lt list gt lt listitem gt lt para gt a diesel powered unicycle lt para gt lt listitem gt lt listitem gt lt para gt a stretch limousine about 50 yards long lt para gt lt listi ten lt listitem gt lt para gt and the cutest little pod cars shaped like spheres with caterpillar tracks on the bottoms lt para gt lt listitem gt eC liet lt para gt I made to intercept the truck to hitch up my vehicle and climb aboard para ole lt para gt If you want to chain up your car to a moving truck you had better know what you are doing lt para gt lt note gt lt J setio dog Example 4 4 is the SimpleDoc DTD Example 4 4 The SimpleDoc DTD d bee SimpleDoc DTD mee pepe iuc uuu cx cue Parameter Entities l Attributes used in all elements lt IENTIIY 4 common atts id LD IMPLIED class CDATA IMPLIED xml space default preserve default s l Inline elements 1l Block and complex elem
327. iews covering all aspects of programming Go to http www ddj com for online content and subscribe to the magazine while you re there Perl com Perl is an interpreted programming language for any kind of text processing including XML The best place online for information or to download code and modules ishttp www perl com J avasoft The best source for Java news and information ishttp www javasoft com Java is a programming language available for most computers and contains a lot of XML support including implementations of SAX and DOM as well as several great parsers Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB A 2 Books XML in a Nutshell 2nd Edition Elliotte Rusty Harold and W Scott Means O Reilly amp Associates A comprehensive desktop reference for all things XML The XML Bible 2nd Edition Elliotte Rusty Harold Hungry Minds A solid introduction to XML that provides a comprehensive overview of the XML landscape HTML and XHTML the Definitive Guide Chuck Musciano and Bill Kennedy O Reilly amp Associates A timely and comprehensive resource for learning about HTML Developing SGML DTDs From Text to Model to Markup Eve Maler and Jeanne El Andaloussi Prentice Hall A step by step tutorial for designing and implementing DTDs While this book is about SGML much of its advice is still excellent for XML The SGML Handbook Charles F Goldfarb Oxfo
328. ign details are inextricably mixed with the content You have to get into the document itself anytime you need to make a change to the design This can be quite laborious For example to change italicized proper nouns to bold typeface means editing each case manually since no automatic search and replace utility can recognize downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir a proper noun from an emphasized phrase Stylesheets untangle presentation details from the document and store them in a separate place If you need to make a change to the design of a document you can change one place in the stylesheet rather than manually fix every hard coded tag in the markup What s more since one stylesheet can be used for many documents seeFigure 5 1 one simple change can affect many pages In a setting where design changes occur frequently this is a godsend Figure 5 1 One stylesheet used by many documents Stylesheet O Yr O 7 O d O o 4 4 4 XML Document XML Document XML Document Dubious vendor extensions Seeking to extend their market share by addressing the frustrations of web authors some tool vendors have taken the initiative of extending HTML on their own circumventing the standards process Differentiating their products this way seems good at first but it leads to a horrible fracturing of your audience People have to use the same tools as you in order to view your information
329. imal number consisting of the delimiter amp 1 the number 2 and a semicolon 3 Figure 2 18 Numeric character reference decimal Figure 2 19 shows another form using a hexadecimal number The difference is that the start delimiter includes the letter x Figure 2 19 Numeric character entity reference hexadecimal For example a lowercase c with a cedilla is the 231st Unicode character It can be represented in decimal as 231 or in hexadecimal as amp xe7 Note that the hexadecimal version is distinguished with an x as the prefix to the number Valid characters are x9 xA xD 4x20 through xD7FF xE000 through xFFFD and x10000 through x10FFFF Since not all hexadecimal numbers map to valid characters this is not a continuous range will discuss character sets and encodings in more detail in Chapter 9 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Named character entities The problem with numbered character references is that they re hard to remember you need to consult a table every time you want to use a special character An easier way to remember them is to use mnemonic entity names Thesenamed character entities use easy to remember names like THORN which stands for the Icelandic capital thorn character Unlike the predefined and numeric character entities you do have to declare named character entities In fact they are technically no different from oth
330. imitive liquid crystal display lt para gt lt footnote gt When your amp productname starts up it should show a status display like this lt para gt lt screen gt STATUS DISPLAY amp l CHE NOTE 22 gt BATT 1 782E8 V TEMP 284 K FREO 9 252HB5 Hz WARRANTY ACTIVE lt screen gt sectl secti lt title gt The Battery lt title gt lt para gt Your amp productname is capable of generating tremendous amounts of energy For that reason any old battery won t do The power source is a tiny nuclear reactor containing a piece of ultra condensed plutonium that provides up to 10 megawatts of power to your device With a half life of over 20 years it will be a long time before a replacement is necessary lt para gt secti chapter lt I book gt 3 2 1 Notes 1 I m taking the opportunity to declare some entities in the internal subset This will save me some t later 2 Notice that all the major components preface chapter sections start with atitle element This example of how an element can be used in different contexts In a formatted copy of this documen titles in different levels will be rendered differently A stylesheet will use the hierarchical informatio i e what is the ancestor of thistitle to determine how to format it 3 orderedlist is one of many types of lists available in DocBook It produces the equivalent of HTM downloaded from lib ommolketab ir downloaded from fib
331. imm d lt 1 gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt l gt But thy eternal summer shall not fade lt 1 gt lt 1 gt Nor lose possession of that fair thou owest lt 1 gt l Nor shall Death brag thou wander st in his shade lt 1 gt lt l gt When in eternal lines to time thou growest 1 1 So long as men can breathe or eyes can see l 1 So long lives this and this gives life to thee 1 lt Lg e dae oh lt text gt lt TEI 2 gt A typical TEI document consists of two parts a metadata section in ateiHeader element and the text body in a text element Using an XSLT stylesheet we will transform this into an FO tree then run the tree through a formatter to generate a formatted page Actually used FOP for this which combines the XSLT transformation and XSL FO formatting intoone step for me TEI The Text Encoding Initiative TEI is an international standard for libraries museums and academic institutions to encode scholarly texts for online research and sharing Founded ir 2000 by several collaborating research groups the TEI Consortium is funded by the National Endowment for the Humanities the European Union the Canadian Social Research Council and private donors It publishes a DTD for marking up texts and a detailed tutorial TEI XML is a markup language that can be applied to anything from groups of books to plays and poetry Its hallmarks includ
332. imple to write a program that interfaces with this driver to assemble anXML document containing requested data We will go over SAX in Chapter 10 Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 3 2 Narrative Documents Now let s look at an important category of XML A narrative document contains text meant to be read by people rather than machines Web pages books journals articles and essays are all narrative documei These documents have some common traits First order of elements is inviolate Try reading a book backward and you ll agree it s much less interesting that way and it gives away the ending The text rt a single path called aflow which the reader follows from beginning to end Another key feature of narrative documents is specialized element groups including sections blocks an inlines Sections are what you would imagine elements that break up the document into parts like chap subsections and so on Blocks are rectangular regions such as titles and paragraphs Inlines are strings inside those blocks specially marked for formatting Figure 3 2shows how a typical formatted document would render these elements Figure 3 2 Flows blocks inlines 3 2 1 Flows and Sections A narrative document contains at least one flow a stream of text to be read continuously from start to finish If there are multiple flows one will be dominant branching occasionally into
333. inally we can define the templates for inline elements In this particular stylesheet they fall into a few categories of presentation italic monospace subscript Superscript and small caps lt xsl template match citetitle command emphasis filename firstterm foreignphrase replaceable gt fo inline font style italic gt xsl apply templates lfosi mline lt xsl template gt lt xsl template match function literal option parameter returnvalue symbol type gt fo inline font family monoco monospace font size 9pt gt xsl apply templates lt fo inline gt lt xsl template gt 1 Note use of vertical align property to lower the font baseline Also using relative size to make it smaller lt xsl template match subscript gt lt fo inline font size 60 vertical align sub gt xsl apply templates amp fosinline lt xsl template gt lt xsl template matcechi guperscript gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt fo inline font size 60 vertical align super gt xsl apply templates lt fo inline gt lt xsl template gt lt Font variant property here to set all caps for acronyms gt lt xsl template match acronym gt lt fo inline fonrt varlante small caps s xsl apply templates forinline gt lt xsl template gt lt xsl stylesheet gt 8 6 9 Results As a source d
334. ine what values map to when transformed to another type XPath has a rich set of operators and functions for working with each expression type In the following sections will describe these and the rules for switching between types 6 3 1 Boolean Expressions Boolean expressions have two values true or false As you saw with location step predicates anything inside the brackets that does not result in a numerical value is forced into a Boolean context There are other ways to coerce an expression to behave as Boolean The functionboolean derives a true or false value from its argument There are also various operators that combine and compare expressions with a Boolean result The value derived from an expression depends on some rules listed inTable 6 6 Table 6 6 Boolean conversion rules downloaded from lib ommolketab ir downloaded from lib ommolketab ir Expression type Rule Node set True if the set contains at least one node false if it is empty E String eee nes A TUM unless the string is zero length Number True unless the value is zero or NaN True unless the value is zero or NaN not a number a number Result tree Always true because every fragment contains at least one node its root fragment node Certain operators listed in Table 6 7 compare numerical values to arrive at a Boolean value These are existential comparisons meaning that they test all the nodes in a node
335. ines A syntax error is easy to create and may be difficult to locate XML s explicit markup gives it natural immunity to these types of problems If you are writing a program that reads or saves data to a file there are good reasons to go with XML Parsers have been written to parse it already so all you need to do is link to a library and use one of several easy interfaces SAX DOM or XPath Syntax errors are easy to catch and that too is automated by the parser Technologies like DTDs and Schema even check the structure and contents of elements for you to ensure completeness and ordering 3 1 1 Dictionaries A dictionary is a simple one to one mapping of properties to values A property has a name orkey which is a unique identifier A dictionary is kind of like a table with two columns It s a simple but ver effective way to serialize data In the Macintosh OS X operating system Apple selected XML as its format for preference files called property lists For the Chess program the property list is in a file calledcom apple Chess plist shown here lt xml version 1 0 encoding UTF 8 gt SIDOCTYPER plist SYSTEM rile localhost S5ystem LlbDtarv DTIDs PropertyList dbto plist version 0 9 gt CODD lt KEY VALUE Exe lt key gt BothSides lt key gt lt false gt lt key gt Level lt key gt lt integer gt 1 lt integer gt lt key gt PlayerHasWhite lt key gt lt true gt lt key gt SpeechRecognition lt key gt lt f
336. ing the lower and upper bounds respectively Any element set to the typemonthNum will be checked to ensure its value is a number that falls inside that range Besides setting ranges facets can create fixed values constrain the length of strings and match patterns with regular expressions For example say you want the postal code to be any string that contains three digits followed by three letters as in the census example lt postalcode gt 885JKL lt postalcode gt A pattern to match this is 0 9 0 9 0 9 A Z A Z A z Even better 0 9 3 A Z 3 Here is how the schema element might look lt xs element name postalcode type pcode gt xs simpleType name pcode gt xs restriction base xs token gt xs pattern value 0 9 3 A 2 3 gt clxpryestr ictlon xs simpleType Another way to define a type is by enumeration defining a set of allowed values Thegender element for example may only contain two values emale or male Here s a gender type xs simpleType name genderType gt xs restriction base xs token gt xs enumeration value female gt xs enumeration value male gt elxetrastrictions xs simpleType Now let me show you how would write a schema for the CensusML document type Example 4 6 shows my attempt Example 4 6 A schema for CensusML xs schema xmlns xs http www w3 0rg 2001 XMLSchema downloaded from lib ommolketab ir downloaded from l
337. inition sCommon atts amp l ppomponem E a Ligt gt lt ELEMENT listitem block group gt lt ATTLIST listitem common atts gt See Int low HORS gt lt ELEMENT note parat gt lt ATTLIST note common atts gt pASIO Paragraph gt numbered lt ELEMENT para PCDATA inline group footnote lt ATTLIST para ecommon auttsj amp l Code diting gt lt ELEMENT codelisting PCDATA inline group SIATINISI Godelisting xml space preserve FIXED preserve 6common atts visible comment gt lt ELEMENT remark PCDATA Sinline group gt lt ATTLIST remark Scommon atts gt l document or section label gt lt ELEMENT title PCDATA 6inline group gt lt ATTLIST title common atts term in a definition list gt lt ELEMENT term PCDATA inline group lt ATTLIST term common atts downloaded from fib ommolkcetftab ir downloaded from lib eommolketab ir SENTITI lt ELEMENT SIAITLISI lt ELEMENT lt ATTLIST lt ELEMENT lt ATTLIST lt ELEMENT inline conrent SPCDATA acronym inline content acronym scommon atts gt citation inline content Citation scCommon atts gt command inline content gt command scommon atts gt date inline content lt ATTLIST date common atts lt ELEMENT emphasis inline content lt ATTLIST emphasis co
338. ins all the other elements and content in the document Figure 2 2 Parts of an XML document The prolog is optional If you leave it out the parser will fall back on its default settings For example it automatically selects the character encoding UTF 8 or UTF 16 if detected unless something else is specified The root element is required because a document without data is just not a document l 11 1 Interestingly there is no rule that says the root element has to contain anything This leads to the amusing fact that the following smiley of a perplexed bearded dunce is a well formed document lt gt It s an empty downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir element whose name is Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 2 3 The Document Prolog Being a flexible markup language toolkit XML lets you use different character encodings define your ow grammars and store parts of the document in many places An XML parser needs to know about these particulars before it can start its work You communicate these options to the parser through a construc called the document prolog The document prolog if you use one comes at the top of the document before the root element There are two parts both optional an XML declaration and a document type declarationl The first sets parameters for basic XML parsing while the sec
339. internal workings Therefore it the same standards Opera Opera is a fast and efficient browser whose lead designer was one of the codevelopers of CSS1 S support varies with platform the Windows version being strongest It implements XML parsing CS level 2 WAP and WML media for wireless devices such as cell phones and Unicode An exciting venture with IBM has formed recently to develop a multimodal browser that will handle speech as keyboard mouse control Opera s weakest point is DOM with only limited support X Smiles This fascinating tool describes itself as an open XML browser for exotic devices It supports some no other browsers have touched yet including SMIL XForms X3D three dimensional graphics a Signature Using a Java based plug in it can parse XML and do transformations with XSLT You can see browsers vary considerably in their support for standards CSS implementation is particular shown in Eric Meyer s Master Compatibility Chart at http www webreview com style css1 charts mast People aren t taking the situation lying down however The Web Standards Project http www webst monitors browser vendors and advocates greater compliance with standards Things get really interesting when you mix together different XML applications in one document Exampl document that combines three applications in one XHTML which forms the shell and handles basic text SVG for a vector graphic and MathML to include an equation at the
340. ion gt ch lt xsl text gt Expenditures from xsl text lt xsl value of select 2 child 1 date Cxelstexto until e xsl itext xslevalue of selecte ochilds last date lt xsl text gt ranked from highest to lowest lt xsl text gt lt h3 gt xsl apply templates select payment gt xsl sort data type number order descending select amount xsl apply templates hs Balances h3 lt o gt xsl text Your balance as of lt xsl text gt lt xsl value of select child last date lt xsl text gt is lt xsl text gt erp pe lt xsl choose gt xsl when test sum payment amount gt sum deposit amount lt font color red gt lt xsltext gt o lt xslitext gt lt xsl value of select sum deposit amount sum payment amount sJ Pome lt xsl when gt downloaded from lib ommolketab ir downloaded from lib ommolketab ir lt xsl otherwise gt lt font color blue gt exel ttextob xslitext lt xsl value of select sum deposit amount sum payment amount lt font lt xsl otherwise gt xsl choose CO LS 03 xsl if test sum payment amount sum deposit amount p lt font color red gt lt xsl text gt DANGER Deposit money quick lt xsl text gt y Tonto lt p gt lt 7 Red iL lt body gt lt html gt lt xsl template gt Now we need some rules to handle the payment and deposit elements
341. ions are arranged on a page in Ir tb mode Figure 8 6 Page regions downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Viewport rectangle margin top H E margin right region body region end page height imate Oo margin bottom page width When constructing a page master you include a formatting object to represent each area For example region body Is the FO that sets up the geometry for the body region of a page master Each region FO may have a region name attribute that provides a label for flows to attach to it If you don t define a label XSL assigns an implicit name with xsl followed by the FO type For example the default name for region body IS xsl region body rto layout master set lt fo simple page master master name simple page height 1lin page width 8 51in margin top lin margin bottom lin mergin lefrte l 2150 sardgin righrte 1l 2imn gt lt fo region body region name pamphlet body margin top lin lt fo region before region name company logo extent l lin display align 2 before fo region start region name navigation menu extent 1 lin gt lt fo simple page master gt fo layout master set The margin properties for region FOs position them within the content rectangle of the page In the above example margin top sets the top of the body region to be one inch below the top of the page s content rectangle In the periphera
342. ir out The first font size property originates from the rule with selectorp big which is more descriptive than p or so it s the winner In the final analysis these three properties will apply font size 18pt font family garamond serif color Diack 5 2 4 Property Inheritance XML documents have a hierarchy of elements CSS uses that hierarchy to pass along properties in a process called inheritance Going back to our DocBook example a sect1 contains a para Consider the following stylesheet secti margin left 25pt margin igit 5ptj lIonL 51ze6 ISDL Colors navy para margin top lUpr mMargin bpottomn IDDL L nt s1ze 122p j The para s set of properties is a combination of those explicitly declared for it and those it inherits from the elements in its ancestry Not all properties are inherited Margins are never inheritable so ii the above example only font size and color may be inherited However the font size property is not inherited by para because it is redefined there So thepara s properties include those specifically defined for it plus the one it inherited color navy 5 2 5 Combining Stylesheets A very powerful feature of CSS is its ability to combine multiple stylesheets by importing one into downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir another This lets you borrow predefined style definitions so you don t have to continuously reinvent the wheel
343. ired sequence of children you can use the group modifier which functions much like parentheses in DTDs For example here the now required authorname Is either plain text or a sequence of elements lt element name report xmlns http relaxng org ns structure 1 0 lt element name title gt lt text gt lt element gt lt element name authorname gt lt choice gt text group lt element name first gt lt text gt lt element gt lt element name last gt lt text gt lt element gt lt group gt lt choice gt lt element gt lt element name body gt lt text gt lt element gt lt element gt The group container is necessary because without it the first and last elements would be part of the choice and become mutually exclusive downloaded from lib ommolketab ir downloaded from lib ommolketab ir DTDs provide no way to require a group of elements in which order isnot significant but contents are required RELAX NG provides a container called interleave which does just that It requires all the children to be present but in any order In the following example title can come before authorname or It can come after lt element name report xmlns http relaxng org ns structure 1 0 lt interleave gt lt element name title gt text element lt element name authorname gt text element lt interleave gt lt element name body gt text eleme
344. irst namespace can be identified by the prefix nw Example 2 2 Document with two namespaces downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Darl Calalog xmlns nw http www nutware com xulnese Uhrtpi www bobco com nw entry nw number 1327 gt nw description torque balancing hexnut lt nw description gt lt nw entry gt part ide 555 lt name gt type 4 wingnut lt name gt lt parce part catalog The attributes of part catalog are called namespace declarations The general form of a namespace declaration is illustrated in Figure 2 12 It starts with the keyword xmins 1 is followed by a namespace prefix 2 an equals sign 3 and a namespace identifier 5 in quotes 4 Figure 2 12 Namespace declaration syntax xmlns Avoid using xm1 as a namespace prefix as it is used in reserved attributes like xml space In a special form of the declaration the colon and namespace prefix are left out creating an implicit unnamed namespace The second namespace declared in the example above is an implicit namespace part catalog and any of its descendants without the namespace prefixnw belong to the implicit namespace Namespace identifiers are by convention assigned to the URL subset of URIs not the more abstract URNs This is not a requirement however The XML processor doesn t actually look up any information located at that site The site may not even exist So wh
345. is Unicode which supports hundreds of scripts Latin Nordic Arabic Cyrillic Hebrew Chinese Mongolian and many more It also has ample supplies of literary and scientific symbols You d be hard pressed to think of something you can t express in XML To be flexible XML also supports many character encodings The difference between a character set and a character encoding can be a little confusing A character set is a collection of symbols or glyphs For example ASCII is a set of 127 simple Roman letters numerals symbols and a few device codes Acharacter encoding is a scheme for representing the characters numerically All text is just a string of numbers that tell a program what symbols to render on screen An encoding may be as simple as mapping each byte to a unique glyph Sometimes the number of characters is so large that a different scheme is required For example UTF 8 is an encoding for the Unicode character set It uses an ingenious algorithm to represent the most common characters in one byte some less common ones in two bytes rarer one in three bytes and so on This makes the vast majority of files in existence already compatible with UTF 8 and it makes most UTF 8 documents compatible with most older 1 byte character processing software There are many other encodings such as UTF 16 and ISO 8859 1 You can specify the character encoding you want to use in the XML prologue like this lt xml version 1 0 encoding 1s
346. is parameter with the witn param element as a child of the call template element Or it may defer to the default value defined in theparam element inside the named template as is the case with the template matchingnote param declares the parameter in the named template The name attribute gives it a label that you can refer to later in an attribute with a dollar sign preceding as in thevalue of element above You may use as many parameters as you wish but each one has to be declared If you use the parameter reference inside a non XPath attribute you need to enclose it in curly braces to force the XSLT engine to resolve it to its text value downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir a href Sfile gt Next Page lt a gt Optionally param may assign a default value using its content The value is a result tree fragment constructed by evaluating the content of theparam element For example you can set it with xsl param name label gt lt span class highlight gt Note lt span gt lt xsl param gt and the parameter will be set to a resulttree fragment containing a span element Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 7 6 Formatting Since XSLT was originally intended for producing human readable formatted documents and not just as a general transformation tool it comes with a decent supply of formatting
347. is would be a mistake The next step is to write the handler class shown inExample 10 3 Example 10 3 Contents of SAXCounterHandler java import org xml sax helpers DefaultHandler import org xml sax Attributes public class SAXCounterHandler extends DefaultHandler private int elements public SAXCounterHandler super handle a start of document event public void startDocument SOvseLrem out pruinrtlni SLarting LO parse elements 0 handle an end of document event public void endDocument System out printin All done downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir system out printin There were elements elements handle a start of element event public void startElement String uri String name String qName Attributes atts System out println starting element qName if equals uri else System out println namespace uri System out println number of attributes atts getLength handle an end of element event public void endElement String uri String name String gName elements F System out println ending element qName handle a characters event public void characters char ch int start int length System out println CDATA length characters This class implements five types of events Start of document Initialize the elements counter and p
348. ith a steep learning curve Its elements are very specie It has blocks for different kinds of code listings scores of inlines for technical terms and many kinds of sections Some users of DocBook think that it may be too big Others feel it s too loose allowing for so r kinds of documents within the technical documentation realm that it suffers from the ambiguity that hinders HTML Despite these complaints DocBook is and always has been the best markup language for technical documentation It s not hard to find tools and support for DocBook Many XML editors XMetaL and Adept for example with DocBook packages already configured Lots of stylesheets schema DTDs and other aids are also available This support is likely to continue as various groups from publishers to the Linux Documentatii Project adopt DocBook as their default standard The first incarnation Example 3 5 is a reformulation of the previous example You ll see that the mark a better fit for this type of data and the element types are much more specific Also note the introducti section elements Example 3 5 A DocBook reference page lt xml version 1 0 lt DOCTYPE refentry PUBLIC OASIS DTD DocBook XML V4 1 EN dusr local dbds docbook41 docbookx dtd lt refentry gt lt refnamediv gt lt refname gt cat lt refname gt lt manvolnum gt 1 lt manvolnum gt lt refmeta role edition gt 3rd Berkeley Distribution May 2 1995 lt refmeta gt lt r
349. ith all the elements that can be interspersed within it Alas there is no way to require that an element with mixed content contains character data The census taker could just leave the street element blank and the validating parser would be happy with that Changing that asterisk to a plus to require some character data is not allowed To make validation simple and fast DTDs never concern themselves with the actual details of character data Our final task is to declare the elements and attributes making up aperson Here is a crack at the element declarations lt ELEMENT person name age gender lt ELEMENT name first last junior senior gt lt ELEMENT age PCDATA gt lt ELEMENT gender PCDATA gt lt ELEMENT first PCDATA gt lt ELEMENT last PCDATA gt lt ELEMENT junior EMPTY gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt ELEMENT senior EMPTY gt lt ATTLIST person pid ID REQUIRED employed fulltime parttime IMPLIED gt The content model is a little more complex for this container The first and last names are required but there is an option to follow these with a qualifier Junior or Senior The qualifiers are declare as empty elements here using the keyword EMPTY and the question mark makes them optional as not everyone is a junior or senior Perhaps it would be just as easy to make an attribute called qualifier with values junior Or senior
350. ith the additional attribute abstract set to yes and an id with some unique value Another rule will reference theid with a rule attribute in an extends child element See the following example rule id inline abstract yes gt lt report test gt Error Element inside inline lt report gt lt assert test text gt Strange there s no text inside this inline lt assert gt lt rule gt rule context bold gt lt extends rule inline gt lt rule gt lt rule context emphasis gt lt extends rule inline gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt rule gt rule context 2 quote extends rule inline gt rule Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 4 6 Schemas Compared Each of the schemas we ve looked at has compelling features and significant flaws Some of the important points are listed Table 4 2 Table 4 2 A comparison of schema Feature DTD W3C Schema RELAX NG Schematron XML syntax No Yes Yes Yes Namespace compatible No Yes Yes Yes Declares entities Yes No No No Tests datatypes No Yes Yes Yes Default attribute values Yes Yes Nol7l No Notations Yes Yes NO NO Unordered content No Yes Yes Yes Modular Yes Yes Yes No Element attribute interchangeability No Yes Yes Yes S pecifies how to associate wi
351. ith the first being qu implemented the second and more advanced less so and the third rarely IE also contains an XSLT transformation engine This gives yet another way to format an XML document script pointed to by your document transforms it into XHTML which IE already knows how to display So two ways inside IE to generate decent presentation making it an invaluable development tool Since no implement CSS and XSLT for XML documents it s risky to serve XML documents and expect end user cli format them correctly This may change soon as more browsers catch up to IE but at the moment it s the transformation on the server side and just serve HTML There are a bunch of browsers capable of working with XML in full or limited fashion The following list d few of the more popular and interesting ones Some technologies like DOM and CSS are broken up intc representing the relative sophistication of features Most browsers completely implement the first level c CSS1 a few CSS2 and hardly any completely support the third tier of CSS Amaya Amaya Is a project by the W3C to demonstrate technologies working together It s both a browser editor with built in XML parsing and validating It supports XHTML 1 1 CSS1 and parts of CSS2 M much of SVG It is not able to format other kinds of XML however Konquerer Available for flavors of Unix this browser has lovely HTML formatting but only limited support for standards set includes HTML 4 most
352. just anywhere we want to force it to break in a downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir specific place Here is what a forced line break would look like lt title gt The Confabulation of Branklefitzers lt lb gt in a Portlebunky Frammins lt lb gt Without Denaculization of lt lb gt Crunky Grabblefooties lt title gt Now you know all the ins and outs of markup You can read and understand any XML document as if you were a living XML parser But it still may not be clear to youwhy things are marked up as they are or how to mark up a bunch of data In the next chapter I ll cover these issues as we look atthe fascinating topic of data modeling Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 3 Modeling Information Designing a markup language is a task similar to designing a building First you have to ask some questions Who am I building it for How will it be constructed How will it be used Do give it man small rooms or a few large ones Will the rooms be generic and interchangeable or specialized Is there are role for the building like storage office space or factory work It takes a lot of planning to do it right When designing a markup language there are many questions to answer What constitutes a document How detailed do you need it to be How will it be generated Is it flexible enough to handle every
353. ka Korpela has assembled a huge amount of information related to character sets at http www cs tut fi 7Ejkorpela The tutorial is well written and very interesting reading XSL mailing list Signing up with the XSL mailing list is a great way to keep up with the latest developments in XSL and XSLT tools and techniques It s also a forum for asking questions and getting advice The traffic is fairly high so you should balance your needs with the high volume of messages that will be passing through your mailbox To sign up go tohttp www mulberrytech com xsl and follow the instructions xml dev mailing list The xml dev mailing list is an extremely busy forum for discussion of all kinds of XML related issues and best practices To sign up go tohttp lists xml org and follow the instructions Apache XML Project This part of the Apache project focuses on XML technologies and can be found at http xml apache org It develops tools and technologies for using XML with Apache and provides feedback to standards organizations about XML implementations XML Developers Guide downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir This guide is the Microsoft Developers Network s online workshop for XML It contains information about using XML with Microsoft applications and can be found at http msdn microsoft com xml XMLGuide Dr Dobb s J ournal This journal contains articles resources opinions news and rev
354. kcefab ir numerical values in its underlying form An encoding scheme is a function that maps sequences of positive integers to a subset of a character set s repertoire The input sequence may or may not have anything to do with the actual code position Quite often an algorithm must be applied to arrive at ai actual code position The need for encodings becomes clear when you consider the vast gulf between character sets and the requirements of devices and protocols Character sets range from tiny 7 bit ASCII to huge 32 bit Unicode Devices and protocols may not be flexible enough to handle this wide variation Internet protocols historically have been defined in terms of 8 bit characters oroctets SO 646 which is based on the 7 bit ASCII character code is designed for 8 bit systems recommending that the eighth bit be set to zero This encoding is just a simple way of making 7 bits seem like 8 bits Mail transport systems such as thesimple mail transfer protocol SMTP have a restriction of 7 bits per character Binary files such as compiled executables have to be encoded such that only the lower bits per byte are used 8 bit character sets also have to be encoded specially so they don t confuse the email transport agent The Unix program uuencode for example turns any binary file into an ASCII string that looks like gibberish but can be turned back into the original binary format later Large character sets such as Unicode are a stick
355. l modifier For example this schema allows you to insert an optional authorname element after the title element name report xmlns http relaxng org ns structure 1 0 lt element name title gt lt text gt lt element gt lt optional gt lt element name authorname gt text element lt optional gt lt element name body gt lt text gt lt element gt lt element gt It is also useful to offer a choice of elements Corresponding to DTD s vertical bar operator is the modifier choice Here we require either an authorname Or a source element after the title element name report xmlns http relaxng org ns structure 1 0 lt element name title gt lt Cext 7 gt lt element gt lt choice gt lt element name authorname gt LCExL gt lt element gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt element name source gt lt text gt lt element gt lt choice gt lt element name body gt lt text gt lt element gt lt elem nt gt This declaration combines choice with zeroOrMore to create a container that can have mixed content text plus elements in any order element name paragraph xmlns http relaxng org ns structure 1 0 lt ZerolUrMore lt choice gt text element name emphasis gt text lt element gt lt choice gt zeroOrMore lt element gt 4 4 1 3 Grouping For a requ
356. l more and cheaper programs available to the public XML s rules are strict but they make the burden of parsing and processing files more predictable and therefore much easier It should enforce maximum error checking Some markup languages are so lenient about syntax that errors go undiscovered When errors build up in a file it no longer behaves the way you want it to its appearance in a browser is unpredictable information may be lost and programs may act strangely and possibly crash when trying to open the file The XML specification says that a file is not well formed unless it meets a set of minimum syntax requirements Your XML parser is a faithful guard dog keeping out errors that will affec your document It checks the spelling of element names makes sure the boundaries are airtight tells you when an object is out of place and reports broken links You may carp about the strictness and perhaps struggle to bring your document up to standard but it will be wortl it when you re done The document s durability and usefulness will be assured It should be culture agnostic There s no good reason to confine markup in a narrow cultural space such as the Latin alphabe and English language And yet earlier markup languages do just that Irked by this limitation XML s designers selected Unicode as the character set opening it up tothousands of letters ideographs and symbols Team LiB downloaded from lib ommolketab ir
357. l pages The element marking the start of the range is indexterm and has the attribute class startofrange The element ending the range is the same type but has an attribute class endofrange The following xpointer would create a range for each pair of such elements xpointer indexterm class startofrange range to following indexterm class endofrange 6 4 4 2 Ranges from points and nodes The function range returns the covering range for every location in its argument the location set A covering range is the range that exactly contains a location For a point the range s start and end points would equal that point a zero length orcollapsed range The covering range for a range is the range itself same start and end points For any other object the covering range starts at the point preceding it and ends at the point following it both of which belong to the object s container node The function range inside changes nodes into ranges For each node in a given location set the function treats it as a container node and finds the start and end points Ranges and points are passed through unchanged 6 4 4 3 Ranges from strings To create ranges for arbitrary regions of text you can usestring range This function takes up to four arguments 1 A location set positions from which to search for strings 2 A string the pattern to match against 3 An offset from the start of the match default is 1 downlo
358. l regions the attributeextent defines the width if it is on the left or right side or height if on the top or bottom Theaisplay align property adjusts where the region sits inside its reference area such as centered or flush left or right downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 8 4 2 Flows A flow is a stream of formatting objects that is to be inserted into an area In the FO tree flows are stored inside page sequence objects They may span many pages or be restricted to a specific area and repeated on multiple pages The latter type is called astatic flow and is typically seen inside a header or footer The children of a flow object are block level flow objects The sequence of these children determine the order in which they will be stacked when formatted inside an area The formatter takes these flov objects and places them into pages according the layout of the appropriate page master Which page master is used depends on the pages that have come before and the page master sequence in use Formatting flows in pages is like pouring liquid into containers The page master is like a mold for casting containers of different shapes tall vases or squat trays The flow objects are a moldable Substance that can be poured into these containers The formatter will create some kind of container depending on which mold it selects When the container is full it casts a new container and pours flow objects
359. l text gt FOOTNOTE lt xsl text gt xsl number value Sfnum format 1 gt lt xsl attribute gt cxclveextc e xalebtexr xsl number value fnum xaBlitext e xSlttexr lt a gt lt xsl template gt lt xsl template match footnote mode tabular gt lt xsl variable name fnum select count preceding footnote ancestor chapter 1 lt a gt xsl attribute name href lt xsl text gt FOOTNOTE lt xsl text gt xsl number value Sfnum format 1 gt lt xsl attribute gt exeletext xsSl te xrt xsl number value Sfnum format a gt saal tert lt a ter gt lt a gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt xsl template gt SXSISDeNDLALte Sadatcou Lable citry xsl apply templates mode tabular gt lt xsl template gt The first rule defines the default behavior of a footnote while the second one sets up the special case for footnotes in tabular mode The behavior differs only in how the footnote number is formatted The third and last rule is a table cell rule that turns on thetabular mode It s important to remember that rules without the mode specifier are not considered by the processor when it s in a specific mode Instead the default rules are used This means you Nave towrite a new rule for every element that might be chosen Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team
360. l1in margin bottom lin Margin LetoaH 1 21n mardgin righr 2 rtotregion body margqin top 20mm gt fo region before extent 0 3in gt lt fo simple page master gt fo layout master set xsl apply templates E TSSqeMES lt xsl template gt 1 Begin the flows gt lt xsl template match TEI 2 gt fo page sequence master reference the only page type gt fo static content flow name xsl region before gt Sere tk ere font family geneva sans serif font size 8pt text align 2 left downloaded from lib ommolketab ir downloaded from lib eommolketab ir border bottom solid lpt black lt xsl value of select teiHeader sourceDesc 7T0osDloOkEs clro BLaLiCc conbtente lt fo flow flow name 2 xsl region body font family didot serif font size lO0pt xsl apply templates select teiHeader title gt xsl apply templates select teiHeader author xsl apply templates select text body eFTroSLlows lt fo page sequence gt lt xsl template gt 1 Render the title in bold to stand out from the sonnet gt lt xsl template match teiHeader title gt mere onke font weight bold space before 2mm space after 4mm xsl apply templates lt Ot block lt xsl template gt 1 Format the author s name in italic to set it apart from the sonnet itself Add the word by for a further decorative touch lt xsl te
361. ld of an element with a bare number A string of numbers like this is called achild sequence and is defined in the XPointer element Scheme recommendation To find the third child of the fifth child of the element whoserp IS 1ooby you can use this xpointer element flooby 5 3 6 4 1 2 Shorthand pointers A shorthand xpointer only contains a string that corresponds to the form of an ID type attribute It substitutes for the ia term making code easier to read and write These two xpointers are equivalent flooby xpointer id flooby 6 4 2 Points A point inside a documentis represented by two things a container node and an index The index counts the number of points from the start of a node beginning with zero If the point is inside text the container is the text node in which it resides not the element containing the text The point may also lie outside of text between two elements for instance Figure 6 2 shows how to find the index for points in a small piece of XML listed here lt para gt These are lt emphasis gt strange lt emphasis gt times lt para gt Figure 6 2 Character points downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir d j LI EE S3 012323 4556 SEHE 0123452587 68 9 0 BIBIBIBID B D 012345287 Inside each text node and any node without children are points between text characters or character points The point to the left of the first
362. le appendix title preface title gt xsl apply templates lt xsl template gt lt xsl template match sectl title gt LIO DIOCK font family myriad verdana sans serif font size 18pt font weight 2 bold space before 8mm space after 4mm xsl apply templates f0sDIlOBk lt xsl template gt lt xsl template match sect2 title gt Cheba ese 6 lt font family myriad verdana sans serif font size 16pt font weight 2 bold space before 8mm space after 4mm downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir xsl apply templates 7 Mae ga oslo et ae lt xsl template gt lt xsl template match example title gt SIOIDIOCE font size 8pt font style italic Space after 2mm keep with next within page always lt xsl text gt Example lt xsl text gt xsl call template name chapnum gt lt xsl text gt lt xsl text gt xsl number format 1 count example from chapter appendix level any xsl apply templates c rosblbopl lt xsl template gt aA ae Return the chapter number or appendix letter If the element contains a label attribute use that Useful if you want to split a document up into multiple documents lt xsl template name chapnum gt lt 25 1 3CnoOose gt xsl when test ancestor or self chapter label gt lt xsl value of select ancestor or self chapter label gt lt xsl when gt xsl when test
363. le these are all acceptable ELEMENT thingie ALL lt ELEMENT thingie ALL lt ELEMENT thingie foo bar Zap 2x 4 2 3 An Example Imagine a scenario where you are collecting information from a group of people The data you receive will be fed to a program that will process it and store it in a database You need a quick way to determine whether all the required information is there before you can accept a submission For this we will use a DTD The information in this example will be census data Your staff is roaming around the neighborhood interviewing families and entering data on their laptop computers They are using an XML editor configured with a DTD that you ve created to model your language CensusML Later they will uploac all the CensusML documents to the central repository to be processed overnight Example 4 1 shows how a typical valid CensusML document should look minus the document prolog A document represents an interview with one family It contains a date an address and a list of people residing there For each person we are interested in taking their full name age employment status and gender We also use identification numbers for people to ensure that we don t accidentally enter in somebody more than once Example 4 1 A typical CensusML document census record taker 3163 gt lt date gt lt year gt 2003 lt year gt lt month gt 10 lt month gt lt day gt 11 lt day gt lt date gt lt
364. le 3 5 the DocBook version of a technical reference page A stylesheet for this might look like Example 5 3 To associate this with the XML document you first have to add this line underneath the XML declaration lt xml stylesheet rel stylesheet type text css href uri gt where uri is the location of the stylesheet Example 5 3 A CSS Stylesheet for a DocBook reference page GLOBAL SETTINGS refentry display block background silver font family serif font size l2pt SECTIONS refnamediv refsynopsisdiv refsectl display block margin top lem downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir margin bottom lem margin left 0 5em margin right 0 5em bpaddinos 0 958 background 499a refnamediv text align center font s1ixe l13DL refsynopsisdiv before content Usage lLonp Iam lys Sans serif font weight bold font size 15pt BLOCKS listitem member para refmeta refpurpose simplelist synopsis term title variablelist display Dlock listitem member margin left 2em margin right 2em para margin 0 5em rerpurpose Io0nrc sbylo italic j refsectl gt title margin top 0 5em margin bottom 0 5em font family sans serif font weight bold loOnL Sniwe lopu simplelist margin left lem synopsis 4 margin top 0 5em margin bottom 0 5em padding 0 5em font family monospace backg
365. le descriptions from different sources Another style description language DSSSL was already being used to format SGML documents Though very powerful DSSSL was too big and complex to be practical for the Web It is a full programming language capable of more precision and logical expression than CSS which is a simple language focused on the basic needs of small documents While other stylesheet languages existed when CSS was proposed none offered the ability to combine multiple sources into one style description set CSS makes the Web truly accessible and flexible by allowing a reader to override the author s styles to adapt a document to the reader s particular requirements and applications The W3C put forward the first CSS recommendation later called CSS1 in 1996 A short time later a W3C working group formed around the subject of Cascading Style Sheets and Formatting Properties to add missing functionality Their recommendation CSS2 increased the language s properties from around 50 to more than 120 when it was released in 1998 It also added concepts like generated text selection by attribute and media other thanscreen display CSS3 is still a work in progress 5 2 2 Syntax Below is a sample CSS stylesheet A simple example addressbook display tyvpet block Lomnrt famlys Sans serif font size 12pt background color white color blue j entry downloaded from lib ommolketab ir downloaded from
366. led doc This object supports two interfaces DOM and XPath used XPath queries as arguments to the methods findnodes and findvalue to reach into parts of the document and pull out elements and character data What could be easier Run the above program on the data file and you ll get tab data Current balance 2781 37 This example shows how XML makes reading and accessing data easy for the programmer What s more the XML is flexible enough to allow you to restructure the data without rewriting the program Adding new fields such as an ID attribute or a time element wouldn t affect the program a bit With an ad hoc solution like the colon delimited usr passwd file you would not have that kind of flexibility 3 1 3 XML and Databases XML is very good at modellingsimple data structures like the examples you ve seen so far We ve seen all kinds of data types represented strings integers real numbers arrays dictionaries records XML is easier to modify than flat files with minimal impact on processing software so you can add or remove fields as you like Writing programs to process the data is easy since much of the parsing work has been abstracted out and plenty of interfaces are available Since XML support is ubiquitous there are many ways to modify the data The downside is that XML is not optimized for rapid repetitive access An XML parser has to read the entire document to pick out even a single detail a huge overh
367. lent support in books and online resources and it s very easy to get started using it For small quick and dirty utilities that achieve fast results it simply cannot be beat Having cut my teeth in the text processing world of publishing found Perl to be a boon Including a Perl example to contrast with J ava gives us a nice range of programming environments t showcase XML development strategies If you are developing a large complex system you will likely want to consider J ava for its robustness and strong object oriented programming capabilities If you want a small tool for simple tasks in shaping your XML files then Perl would be a great candidate The example propose for using DOM is a small application that fixes a simple problem When used to prepare DocBook XML documents for formatting found there were a few common structural errors that would cause problems in the formatting software One of these was the tendency of busy indexing specialists to insert lt indexterm gt elements inside titles It is an easy mistake to make and just as easy to fix Now will show you how to go about solving this problem with Perl My favorite parser in Perl is Matt Sargent s XML LibXML It is an interface to the C library libxml2 which is incredibly fast and reliable This module also implements most of the DOM2 specification and adds XPath node fetching capability In this portion of the script we set up the parser and use it to assemble D
368. lesheets It should look like this lt xml stylesheet type text xml href mytrans xsl gt The type attribute is a MIME type l2 The attribute href points to the location of the stylesheet 2 There is still some confusion at the moment about which value to use here Sometimes text xml is sufficient Internet Explorer 5 will only recognize text xs1 Fortunately XSLT 2 0 will clear up this mess recommending the MIME type text xslt xml Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LIB 7 4 The stylesheet Element As mentioned before XSLT is an XML application so stylesheets are XML documents The document element is stylesheet although you are also allowed to uSetransform if the term stylesheet bugs you This element is where you must declare the XSLT s namespace and version The namespace identifier is http www w3 org 1999 XSL Transform Both the namespace and version attributes are required XSLT can be extended by the implementer to perform special functions not contained in the specification For example you can add a feature to redirect output to multiple files These extensions are identified by a separate namespace that you must declare if you want to use them And just to make things clear for the XSLT engine you should set the attributeextension element prefixes to contain the namespace prefixes of extensions As an example consider the stylesheet element
369. lketab ir downloaded from lib ommolketab ir you will see in Figure 5 16 it adds a previously nonexistent head just before thesynopsis element telling you that this is a Usage synopsis Other elements such aSmanvolnum also add text to make the document more readable and correct The rule matching the term element sets a property we haven t seen before float lets the block exist on the same horizontal level as another block relaxing the requirement of vertical alignment By setting it to float left the list terms and definitions can sit side by side making a more compact and readable list Figure 5 16 Browser view of the CSS formatted DocBook document EN 058 Thalz27PM A Navigator File Edit View Go Baokrearks Winde Help ao 6 uri tel Em i a uita R3 fiac boca heed Urso jary i necham ba a m a E eal iiim ble May 2 1735 Wiel Usage Hee henstuw FELE ai Description Tha eat aiy pesh files sequentially re edge erat eoe in comma lizz ond A angle dad nyeriensis Lhe alan imp Ths pins are m ali bapli the n opna Buc doant camber blank lie inps he r optas md dpl a dellar og 5 sk the eed of amh line gs oe Sumner far asipi iaa ssetng gi l Tpi melliple alh creply Gre daina De culpul b be epic qed Emiglies be v opos and iEsplays ab heana ks afr as wel The u option guerencoes rar the cupiat os uebulTerad Diyir sie pining Daab so rng anc enible er drcum ua a
370. ll be false value The attribute s value represented as a text node ownerElement DOM 2 only The element to which this attribute belongs 10 9 1 10 Text This type of node represents text 10 9 1 10 1 Methods Here are the methods for the Text class splitText Breaks the text node into two adjacent text nodes each with part of the original text content The first node contains text from the beginning of the original node up to but not including a character whose position is given by o set The second node has the rest of the original node s content This method is useful for inserting a new element inside a span of text 10 9 1 11 CDATASection CDATASection is like a text node but protects its contents from being parsed It may contain marku characters lt amp that would be illegal in text nodes Use genericNode methods to access data 10 9 1 12 ProcessinglInstruction This class represents processing instructions 10 9 1 12 1 Properties Here are the properties for theProcessingInstruction Class Carget The target value for the node data The data value for the node downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 10 9 1 13 Comment This is a class representing comment nodes Use the genericNode methods to access the data 10 9 1 14 EntityReference This is a reference to an entity defined by anEntity node Sometimes the parser will be configured to resolve all enti
371. ll your program needs to do is read in the XML file and convert the markup into some convenient data structure using an XML parser This software component reads and digests XML into a more usable form There are lots of libraries that will do this as well as standalone programs Outputting XML is just as easy as reading it Again there are modules and libraries people have written that you can Incorporate in any program XML is a very good choice for storing data in many cases It s easy to parse and write and it s open for users to edit themselves Parsers have mechanisms to verify syntax and completeness so you can protect your program from corrupted data XML works best for small data files or for data that is not meant to be searched randomly A novel is a good example of a document that is not randomly accessed unless you are one of those people who peek at the ending of a novel before finishing whereas a telephone directory is randomly accessed and therefore may not be the best choice to put downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir in a single enormous XML document If you want to store huge amounts of data and need to retrieve it quickly you probably don t want tc use XML It s a sequential storage medium meaning that any search would have to go through most of the document A database program like Oracle or MySQL would scale much better caching frequently used data and using a hash table to zer
372. lock class xmlns http relaxng org ns structure 1 0 choice lt element name title gt lt text gt lt element gt lt element name para lt text gt lt element gt lt choice gt lt define gt The usefulness of aggregate definitions becomes more clear when used with patterns in other files 4 4 7 Modularity Good housekeeping of schemas often requires putting pieces in different files Not only will it make parts smaller and easier to manage but it allows them to be shared between schemas 4 4 7 1 External references The pattern externalRef functions like ref and uses the attribute href to locate the file containing a grammar externalRef references the whole grammar not a named pattern inside it Suppose we have a file section rng containing this pattern grammar xmlns http relaxng org ns structure 1 0 SOLAPLe ref name section gt start define name section lt element name section gt lt zeroOrMore gt ret name paragraph s lt zeroOrMore gt lt zeroOrMore gt lt ref name section gt lt zeroOrMore gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt element gt lt define gt lt define name paragraph gt lt text gt lt define gt lt grammar gt We can link it to a pattern in another file like this lt element name report xmlns http relaxng org ns structure 1 0 lt element name title gt lt t
373. lor red gt Dr Indigo Riceway lt font gt lt font gt lt blockquote gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt oi1v gt lt 560 7 lt neml gt Figure 1 3 Transformation result telegram to Sarah Bellum from Colonel Timeslip subj Robot sitting instructions Thanks for watching my robot pal Zonky while I m away He needs to pe recharged twice a day and if he starts to get cranky give him a quart of oil I ll De pack soon after I ve tracked down that evil mastermind Dr Indigo Rice 1 3 2 3 Transformation and formatting objects Transforming XML into HTML is fine for online viewing It is not so good for print media however HTML was never designed to handle the complex formatting of printed documents with headers and footers multiple columns and page breaks For that you would want to transform into a richer format such as PDF A direct transformation into PDF is not so easy to do however It requires extensive knowledge of the PDF specification which is huge and difficult and much of the content is compressed A better solution is to transform your XML into an intermediate format one that is generic and easy for humans to understand This is XSL FO the style language for formatting objects Aformatting object Is an abstract representation for a portion of a formatted page You use XSLT to map element to formatting objects and an XSL formatter turns the formatting
374. lp you are e Making design changes easier by disentangling the details from the document e Enabling multiple uses for one document e Giving the end user more control and accessibility downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The key to all this is what we in XML intellectual circles calllate binding Keep the document as far away from its final product as possible and you maximize its flexibility The stylesheetextends the information into a particular realm be it online viewing or print or spoken text 5 1 2 How They Work Think of applying a stylesheetto a document as preparing a meal from a cookbook Your XML document is a bunch of raw unprocessed ingredients the stylesheet is a recipe telling the chef how to handle each ingredient and how to combine them The software that transmutes XML into another format based on the stylesheet s instructions is the chef in our analogy After the dicing mixing and baking we have something palatable and easily digested 5 1 2 1 Applying properties In the simplest sense a stylesheetis like a table that maps style properties to elements in the document see Figure 5 3 A property is anything that affects the appearance or behavior of the document such as typeface color size or decoration Each mapping from element to property set Is called a rule It consists of a part that matches parts of a document and another that lists the properties to use
375. lready in use by visually challenged people We can expect its use only to increase so the XSL designers have planned its support from the beginning The aural medium has many analogies to typographical styles Where a visual medium would use Space to separate objects an aural processor would use an interval of silence Emphasized text coulc be rendered in higher pitch different volume or altered speed In place of typefaces you might thinl of the kind of voice used such as a child s older man s or a robot s Though would love to explore these properties in this book constraints of scope and the printed medium prevent me from doing an adequate job So I will leave that for another writer and concentrate on visual formatting instead downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 8 1 4 Formatters There are a variety of implementationsof XSL FO formatters available from free and open source to commercial products At the time of this writing here is what found available Name Maker Availability i FOP Apache org Open source J ava application XEP RenderX Commercial product i E3 Arbortext Component in commercial XML publishing system PassiveTeX TEI Open source i Document Server 5 0 Adobe i Commercial product E XSL Formatter AntennaHouse Commercial product Implementations vary in how well they conform to the XSL specification The recomm
376. lse 00 Negates the value of the Boolean expression true if the expression is false not expr otherwise false 6 3 2 Node Set Expressions A node set expression is really the samething as a location path The expression evaluates to a set o nodes This is a set in the strict mathematical sense meaning that it contains no duplicates The Same node can be added many times but the set will always contain only one copy of it XPath defines a number of functions that operateon node sets listed in Table 6 9 Table 6 9 Node set functions Function Returns The number of items in node set For example count parent will return the value O if the context node is the document element Otherwise it will return l since a node can only have one parent count node set A string containing a unique identifier for the first node innode set or for the context node if the argument is left out This string is generated by the processor and guaranteed to be unique for each node generate id node set The number of the last node in the context node set 1ast is similar to last count except that it operates only on the context node set not on an arbitrary set local name The name of the first node in node set without the namespace prefix Without node set an argument it returns the local name of the context node m COS Nee The name of the first node innode set including the namespace prefix uri
377. lt assert gt assert test body gt Yikes It s missing a body assert report test body gt Yup found a body lt assert gt rule lt pattern gt lt pattern name Type 2 gt lt p gt Type 2 reports should have a title and lt em gt at least three lt em gt sections lt p gt lt rule context gt lt assert test report gt Wrong root element This isn t a report lt assert gt lt rule gt lt rule context report gt assert test title Darn It s missing a title lt assert gt lt report test title gt Yup found a title lt assert gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir assert test count section amp gt 2 gt There are not enough section elements in this report lt assert gt report test count section amp gt 2 gt Plenty of sections so I m happy lt assert gt lt rule gt lt pattern gt lt schema gt Now let s run the Schematron validator on this document lt report lt title gt A ridiculous report lt title gt eDpodguvo lt para gt Here s a paragraph lt para gt lt para gt Here s a paragraph lt para gt lt body gt lt report gt used a version of Schematron that outputs its report in HTML form Figure 4 1 shows how it looks in my browser Figure 4 1 A Schematron report 4 5 2 Abstract Rules An abstract rule allows you to reuse rules when they are likely to appear often in the schema The syntax is the same w
378. lt day gt lt date gt lt payor gt Bob s Bolts lt payor gt lt deposit gt lt debit category withdrawal gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt amount gt 40 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 8 lt day gt lt date gt lt description gt pocket money lt description gt lt debit gt lt debit category Savings gt lt amount gt 25 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 8 lt day gt lt date gt lt debit gt debit category medical check 855 gt lt amount gt 188 20 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 8 lt day gt lt date gt lt payto gt Boston Endodontics lt payto gt lt description gt cavity lt description gt lt debit gt debit category supplies gt lt amount gt 10 58 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 10 lt day gt lt date gt lt payto gt Exxon Saugus lt payto gt lt description gt gasoline lt description gt lt debit gt lt debit category car gt lt amount gt 909 56 lt amount gt lt date gt lt year gt 2002 lt year gt lt month gt 1 lt month gt lt day gt 14 lt day gt lt date gt lt payto gt Honda North lt payto gt lt description gt car repairs lt description gt lt debit gt lt debit
379. lt namespace element gt See also element qualified element name namespace node This term comes from the realm of computer science where it s used to describe a point in an abstract network of connected items In XML it refers to either a branching point in a document tree or a leaf of the tree The nodes recognized by XPath include elements attributes processing instructions comments contiguous pieces of character data text namespace declarations and the root node See alsonode tree node tree The hierarchical view of the nodes in a document Starting at the root node the node tree downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Shows which nodes contain other nodes See alsodocument tree node notation Data that should not be parsed or that has special processing needs Is labeled as a notation type with an attribute or external entity A notation declaration in a DID defines notation types used by the XML processor in order to route the data to a special handler Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB O open standard A technical specification released to the public for unrestricted use Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB P PCDATA An element content type consisting of parsed characters i e entity references but no element
380. lt title gt CAT 1 System General Commands Manual lt title gt lt head gt body lt h1 gt CAT 1 System General Commands Manual lt hl gt lt h2 gt NAME lt h2 gt downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir lt p gt cat concatenate and print files lt p gt h2 oYNOPSIS h2 lt p gt cat benstuv lt em gt file lt em gt lt p gt lt h2 gt DESCRIPTION lt h2 gt lt p gt The lt i gt cat lt i gt utility reads files sequentially writing them to the standard output The file operands are processed in command line order A single dash represents the standard input erp ep The options are as follows lt p gt SOLL sde pedt lt dd gt Implies the lt tt gt n lt tt gt option but doesn t number blank lines Lad lt dt gt e lt dt gt lt dd gt Implies the lt tt gt v lt tt gt option and displays a dollar sign at the end of each line as well er dd gt dt n dt lt dd gt Numbers the output lines starting at 1 lt dd gt dt s dt lt dd gt Squeezes multiple adjacent empty lines causing the output to be single spaced lt dd gt amp dLo Led lt dd gt Implies the lt tt gt v lt tt gt option and displays tab characters as tt I tt as well lt 7 dd gt dt uc dt Sou The lt tt gt u lt tt gt option guarantees that the output is unbuffered lt ad gt dt v dt SO Displays non printing characters so they
381. lt xsl text gt lt xslitext gt xsl apply templates ffostabl e captlon lt xsl template gt xXSlttemplarte Malcni Coroup gt sIO CADIE table layout fixed widthz 4 7in space after 4mm margin left 4mm border bottom dotted lpt gray xsl apply templates lt fo table gt lt xsl template gt CxslfLemplarte talci Colspec gt lt fo table column column number count preceding sibling colspec 1 column width colwidth gt lt xsl template gt lt xsl template match thead gt lt fo table header background color silver font weight bold xsl apply templates lt fo table header gt lt xsl template gt xsltLemDlate Macchi LoGody gt lt fo table body gt xsl apply templates fo table body lt xsl template gt lt xsl template match tfoot gt lt fo table footer gt xsl apply templates fo table footer lt xsl template gt lt xsl template match row gt downloaded from lib eommolketab ir downloaded from lib ommolketab ir lt fo table row gt xsl apply templates fo table row lt xsl template gt lt KxSLitemplate Malcn enery gt lt fo table cell gt lt I TOLO font family verdana sans serif padding top 1mm padding bottom 1mm padding left 3mm padding right 3mm text align left xsl apply templates lt Tro block gt fo table cell lt xsl template gt 8 6 8 Inlines F
382. m LiB 7 3 Running Transformations There are several strategies to performing a transformation depending on your needs If you want a transformed document for your own use you could run a program such asSaxon to transform it on your local system With web documents the transformation is performed either on the server side or the client side Some web servers can detect a stylesheet declaration and transform the document as it s being served out Another possibility is to send the source document to the client to perform the transformation Internet Explorer 5 0 was the first browser to implement XSLTHI opening the door to this procedure Which method you choose depends on various factors such as how often the data changes what kind of load your server can handle and whether there is some benefit to giving the user your source XML files 1 Actually this isn t strictly true as one of my reviewers pointed out Jeni Tennison writes Internet Explorer 5 0 didn t support XSLT unless you installed MSXML3 in replace mode Otherwise it supported WD xsl Microsoft s version which is a bastardized attempt at implementing XSLT It was still useful but incompatible with every other XSLT implementation including later Microsoft work If the transformation will be done by the web server or client you must include a reference to the stylesheet in the document as a processing instruction similar to the one used to associate documents with CSS sty
383. markup containment inline formatting without content aggregation models 2nd 3rd mixed rectangles XML documents context nodes downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir contextual selection CSS conversion Boolean rules numeric expressions PYX string expressions core syntax counters CSS covering ranges cross references CSS Cascading Style Sheets 2nd box model documents formatting properties blocks display types generated text inheritance 2nd matching to elements text units of measurement properties declaration rules matching troubleshooting specifications stylesheets applying associating combining limitations of need for syntax current node current node set customizing DTDs Team LiB downloaded from fib ommolkcetftab ir downloaded from fib ommolkcetftab ir Team LiB AT B C D E F G H 1 J K L M EN O P Q R S ET U V W X data binding data type identifiers data typing RELAX NG databases DCD Document Content Description DDML Document Definition Markup Language declarations 2nd 3rd 4th 5th CSS DTDs functions organizing by namespaces properties stylesheet rules schemas stylesheets variables default rules XSLT defining type delimiter depth first searching descriptive standards design See also formatting DTDs development dictionaries dimensions are
384. med template Since you can call a named template as many times as you want let us put the navigation menu at the top and bottom o the page lt xsl template match page gt lt body gt lt xsl call template name navbar gt xsl apply templates xsl call template name navbar gt lt body gt lt xsl template gt If you want to change the context node set for a named template you must enclose the call in a for each element lt xsl template match cross reference gt lt xsl variable name reference select ref gt lt xsl for each select id Sreference gt xsl call template name generate ref text xsl for each lt xsl template gt What this template does is handle the occurrence of a cross reference which is a link to another element in the same document For example an entry in a dictionary might have a see also link to another entry For an element of type cross reference this template finds the value of itSref attribute and assigns it to a variable As we will see later on when talk more about variables this i a useful way of inserting a piece of text into an XPath expression The or each element then locates the element whose ID matches the reference value and sets that to be the context node downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir before passing control over to the template named generate ref text That template will generate some text
385. ment can appear when placed inside anotherelement declaration For example the following schema declares three elements report title and body and specifies that the first element contains the other two in the exact order and number that they appear lt element name report xmins http relaxng org ns structure 1 0 gt lt element name title lt text gt lt element gt lt element name body gt lt text gt lt element gt lt element gt Whitespace between these elements is allowed as it would be for a DTD Thetext element which is always empty restricts the content of the Inner elements to character content 4 4 1 1 Repetition downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir To allow for repeating children RELAX NG provides two modifier elements zeroOrMore and oneOrMore They function like DTD s star and plus operators respectively In this example the body element has been modified to allow an arbitrary number ofpara elements element name report xmlns http relaxng org ns structure 1 0 lt element name title text lt element gt lt element name pody gt zeroOrMore element name para text element zeroOrMore lt element gt lt element gt 4 4 1 2 Choices The question mark operator in DTDs means that an element is optional zero or one in number In RELAX NG you can achieve that effect with theoptiona
386. ment element or root element which contains all the content of the document See alsodocument document type declaration XML declaration document tree Every XML document can be represented in a special structural form called a tree It s tree like because it originates from one point the root and branches out into leaves Each point in the tree where a branching occurs is called a node A tree consists of a root node many branch nodes and a smattering of leaf nodes Strangely most document trees are drawn upside down with the root on top Document trees can be divided into smaller trees in that any node can be considered the root of its own subtree This fact is important in understanding XML transformations using XSLT which effectively chops a tree into smaller and smaller subtrees then assembles a result tree ii reverse fashion See also document node tree document type declaration The DOCTYPE section of the document prolog This section declares the structure to which the document must conform It can be used to specify a DTD by providing its public identifier and location by URI It can also specify an internal subset of entity declarations used in the document See also document DTD DOM Document Object Model A tree based interface for accessing and manipulating the contents of XML documents downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir DTD document type definition A set
387. ments for the World Wide Web See alsohypertext markup XHTML hypertext A way of linking text or objects in documents that permits nonlinear access to the content See also HTML markup XHTML Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB inheritance The method by which an object retains a setting that was instantiated on its parent object See also CSS rule inline element An element that occurs within the text content of another element for example an emphasized term inside a paragraph See also block element internal subset Elements attributes and other declarations that compose at least part of a DTD and are contained within the document type declaration See See alsodocument type declaration external subset ISO International Organization for Standardization An organization founded in 1947 to create open technical specifications See alsoopen standard recommendation standards body Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB L local resource A resource that contains a link See also remote resource resource simple link logical structure The nodal or hierarchical layout of elements and content in a document as opposed to the physical location of elements and data See alsodocument physical structure Team LIB downloaded from lib ommolketab ir
388. mmolkcefab ir Besides using definite element names you can use an asterisk as a wildcard to match any element name It s called theuniversal selector For example the following rule applies to any element in a document setting the text color to blue x color blue Since this is a very general selector it takes a low precedence in the set of rules Any other element that defines a color property will override this rule 5 3 2 Attributes For a finer level of control youcan qualify the selection of elements by their attributes Anattribute selector consists of an element name immediately followed by the attribute refinement in square brackets Varying levels of precision are available planet atmosphere This selector matches any planet element that has an atmosphere attribute For example it selects planet atmosphere poisonous and planet atmos phere breathable but not planet You can leave out the element name if you want to accept any element that contains the attribute The selector atmosphere matches both planet atmosphere dense gt and moon atmosphere wispy gt planet atmosphere breathable Adding a value makes the selector even more specific This selector matches lt planet atmosphere breathable gt but it doesn t match planet atmosphere poisonous gt planet atmosphere sweet If the attribute s value is a space separated list of strings you can match any one of them
389. mmon atts lt ELEMENT filename inline content lt ATTLIST filename common atts lt ELEMENT firstterm Sinline content gt lt ATTLIST firstterm common atts lt ELEMENT literal tinline content gt lt ATTLIST literal common atts lt ELEMENT quote inline content SIATTLIST quote ecommon dtts lt ELEMENT ulink inline content lt ATTLIST lank href CDATA REQUIRED S6common atts lt ELEMENT xref EMPTY gt lt ATTLIST xref linkend LD REQUIRED sConmon atts lt ENTITY isolatl PUBLIC ISO 8879 1986 ENTITIES Added Latin 1 EN XML i1solatl ent downloaded from fib ommolkcetftab ir downloaded from lib ommolketab ir gt S6isolatl lt ENTITY isolat2 PUBLIC ISO S879 isolatz2 ent gt t isolat2 lt ENTITY isomath PUBLIC 190 2079 isoamso ent gt isomath ENTITY isodia PUBLIC ISO 29791 isodia ent isodia IENTITY isogreek PUBLIC ISO 8879 isogrk3 ent gt isogreek Team LiB downloaded from lib ommolketab ir 1986 ENTITIES 1986 ENTITIES 1986 ENTITIES 1986 ENTITIES Added Latin 2 EN XML Added Math Symbols Ordinary EN XML Diacritical Marks EN XML Greek Symbols EN XML downloaded from fib ommolkcefab ir Team LiB 4 3 W3C XML Schema DTDs are chiefly directed toward describing how elements are arranged in a document They say ven little about the con
390. molkcefab ir Team LiB 6 4 XPointer Closely related to XPath is the XML Pointer Language XPointer It uses XPath expressions to find points inside external parsed entities as an extension to uniform resource identifiers URIs It could be used for example to create a link from one document to an element inside any other Originally designed as a component of the XML Linking Language XLink XPointer has become an important fragment identifier syntax in its own right The XPointer Framework became a recommendation in 2003 along with the XPointer element Scheme allowing basic addressing of elements and the XPointer xmlns Scheme incorporating namespaces The xpointer scheme itself is stuck at Working Draft getting no further development An XPointer instance which I ll just call anxpointer works much like the fragment identifier in HTML the part of a URL you sometimes see on the right side of a hash symbol It s much more versatile than HTML s mechanism however as it can refer to any element or point inside text not just to an anchor element lt a name gt By virtue of XPath it has a few advantages over HTML fragment identifiers e You can create a link to the target element itself rather than to a proxy element e g a name foo gt e You don t need to have anchors in the target document You re free to link to any region in any document whether the author knows about it or not e The XPath
391. molketab ir downloaded from fib ommolkcefab ir The number of characters in the data 10 9 1 7 2 Methods Here are the methods for the CharacterData Class appendData Appends a string of character data to the end of thedata property substringData Extracts and returns a segment of the data property from offset to offset count insertData Inserts a string inside the data property at the location given by offset deleteData Sets the data property to an empty string replaceData Changes the contents of data property with a new string that you provide 10 9 1 8 Element This is the most common type of node you will encounter An element can contain other nodes and has attribute nodes 10 9 1 8 1 Properties Here are the properties for the Element class tagname The name of the element 10 9 1 8 2 Methods Here are the methods for the Element class getAttribute getAttributeNode Returns the value of an attribute or a reference to the attribute node with a given name setAttribute setAttributeNode Adds a new attribute to the element s list or replaces an existing attribute of the same name removeAttribute removeAttributeNode downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Returns the value of an attribute and removes it from the element s list getElementsByTagName Returns a NodeList of descendant elements who match a name normalize Collapses adjacent text nodes
392. mplate match teiHeader author gt lt r O DLOCKk font style italic space after 4mm lt xsl text gt by lt xsl text gt xsl apply templates eFrorDlocks lt xsl template gt lt xsl template match text body gt xsl apply templates lt xsl template gt lt Put the lines in one block to group them together Later we might want to do something special with this grouping such as to surround it in a border Hint we use select here so that We can use position later to select lines for indenting downloaded from fib ommolkcetftab ir downloaded from lib ommolketab ir KeLTcemplalre matsene ig LO sDLOCK lt xsl apply templates select 1 gt lt 7 poslea lt xsl template gt lt As a nice formatting effect we will indent or space certain lines Every other line will be indented 4mm Add space after every fourth line The final two lines are traditionally indented in sonnets lt xsl template match 1 gt SIOSDIODE xsl if test position mod 4 0 gt xsl attribute name space after gt 4mm lt xsl attribute gt C xeltrp lt xsliat Ltesrte position 11 or positiont mod 2 07 gt xsl attribute name start indent 5mm xsl attribute lt xsl i gt xsl apply templates gt lt l Toiblock gt lt xsl template gt lt xsl stylesheet gt Now run the XSLT engine on the document using this stylesheet and you will get the result file in Example 8 4 I ve added
393. mplicitly a predefined entity or explicitly it can t insert replacement text in the document because it doesn t know what to replace the entity with This error preventsthe document from being well formed 2 5 1 Character Entities Entities that contain a single character are called naturally enough character entities These fall into a few groups Predefined character entities downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Some characters cannot be used in the text of an XML document because they conflict with the special markup delimiters For example angle brackets gt are used to delimit element tags The XML specification provides the following predefined character entities so you can express these characters safely Entity Value amp amp apos gt gt LE lt quot i Numeric references XML supports Unicode a huge character set with tens of thousands of different symbols letters and ideograms You should be able to use any Unicode character in your document It isn t easy however to enter a nonstandard character from a keyboard with less than 100 keys or to represent one in a text only editor display One solution is to use anumbered character reference which refers to the character by its number in the Unicode character set The number in the entity name can be expressed in decimal or hexadecimal format Figure 2 18 shows the form of a numeric character entity reference with a dec
394. n this direction too so this distinction is less important e Out of order processing With CSS all the elements in a document are processed in order from start to finish It provides no means of selecting some sections and rejecting others of pulling information from various parts of a document or of processing the same element more than once e XML syntax CSS uses its own syntax making it harder to process XSL is not always preferable to CSS You would choose CSS when you want to keep formatting simple and fast Most web browsers have CSS processing built in but none can do anything with XSL FO XSL FO processing is also very resource intensive You would probably not want to push the burden of formatting on a fickle and impatient user when it could be done ahead of time on your server An important goal of XSL was to make it declarative rather than procedural Adeclarative language expresses a desired outcome with constraints and high level concepts that make it easy to read and understand It also tends to be highly portable since it remains on a conceptual plane By contrast a procedural language is rife with low level clutter such as variable assignments algebra function calls and so on It is typically harder to read and requires someone with erudite skills to work with For example PostScript which is nearly impossible to understand unless you are a hardcore programmer is procedural The XSL Working Group has strived to make
395. name paragraph gt element name para grapn s text lt element gt lt define gt define name section lt element name section gt lt zeroOrMore gt ref name paragraph gt lt zeroOrMore gt lt zeroOrMore gt lt ref name section gt lt zeroOrMore gt lt element gt lt define gt lt grammar gt Failing to put the ref inside an element in a recursive definition would set up a logical infinite loop So this is illegal define name foo gt cope ref name bar gt ref name foo lt choice gt lt define gt The order of definitions for named patterns doesn t matter As long as every referenced pattern has definition within the same grammar everything will be kosher 4 4 6 2 Aggregate definitions Multiple pattern definitions with the same name are illegal unless you use thecombine attribute This tells the processor to merge the definitions into one grouped with either achoice or an interleave container The value of this attribute describes how to combine the parts For example define name block class combine choice gt lt element name title gt lt text gt lt element gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt detine gt define name block class combine choice gt lt element name para gt lt text gt lt element gt lt define gt which is equivalent to this lt define name b
396. nd Syntax Specification became a W3C Recommendation in February 1999 and it is published at http www w3 org TR REC rdf syntax The RDF Schema Specification became a W3C Candidate Recommendation in March 2000 and it is published athttp www w3 org TR rdf schema More recently a number of RDF Working Drafts revising those specs have been published Resource downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Description Framework RDF Concepts and Abstract Syntax is published at http www w3 org TR rdf concepts RDF Semantics is published athttp www w3 org TR rdf mt An RDF Primer is published athttp www w3 org TR rdf primer RDF Vocabulary Description Language 1 0 RDF Schema is published athttp www w3 org TR rdf schema RDF XML Syntax Specification Revised is published athttp www w3 org TR rdf syntax grammar Description RDF is a foundation for using XML to process metadata It provides interoperability between applications that exchange machine understandable information on the Web RDF emphasizes facilities that enable automated processingof web resources Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 9 Multimedia SVG Scalable Vector Graphics is a language describing 2D vector graphics W3C Status The SVG 1 0 specification became a W3C Recommendation in September 2001 The specification is published
397. nd others One critical flaw in using specialty character sets is how to include characters from different sets in the same document A hackish solution is to usecode switching a technique of replacing a byte with a sequence of bytes headed by a special control character Thus you could switch between character sets as necessary and still maintain the 8 bit character stream Although it worked okay it was not an ideal solution By the late 1980s pressure was building to create a 16 bit character set that included all the writing systems into one superset In 1991 the Unicode Consortium began work on the ambitious Unicode character set With 16 bits per code position it had space for 216 65 536 characters The first 256 characters were patterned after ISO 8859 1 ISO Latin 1 of which the first 128 are ASCII The downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Unicode Consortium publishes the specification in a weighty tome with pictures of every glyph and extensive annotations Whereas Western languages tend to be alphabetic composing words in sequences of characters many Eastern languages represent entire words and ideas as single pictures orideographs Since there are many more concepts than sounds in a language the number of ideographs tends to run in the thousands Three scripts Chinese Japanese and Korean have some overlapping glyphs By throwing out the redundancies and combining them in one uni
398. needs to be recharged twice a day and if he starts to get cranky give him a quart of oil I ll be back soon after I ve tracked down that evil mastermind Dr Indigo Ricaew CSS is limited to cases where the output text will be in the same order as the input data It would no be so useful if you wanted to show only an excerpt of the data or if you wanted it to appear in a different order from the data For example suppose you collected a lot of phone numbers in an XML file and then wanted to generate a telephone directory from that With CSS there is no way to sort the listings in alphabetical order so you d have to do the sorting in the XML file first 1 3 2 2 Transformation to presentational formats A more powerful technique is to transform the XML Transformation is a process that breaks apart an XML document and builds a new one The new document may or may not use the same markup language in fact XML is only one option you can transform XML into any kind of text With transformation you can sort elements throw out parts you don t want and even generate new data such as headers and footers for pages Transformation in XML is typically done with the language XSLT essentially a programming language optimized for transforming XML It requires a transformation instruction which happens to be called a stylesheet not to be confused with a CSS stylesheet The process looks like the diagram inFigure 1 2 Figure 1 2 The transformation pro
399. ng that isn t the document node or an element The procedure to be applied comes in the form of a subroutine reference which we dereference to call in two places when the current node is a document node and when it is an element For any other case the subroutine just returns without doing anything Driving this traversal are the methods getDocumentElement which obtains the root element and getChildnodes l3l which returns a list of child nodes in the order they appear in the document 3 No that lowercase n is not a typo Now we turn our attention to the subroutine that performs the fix on elements It is called fix iterms because it moves indexterm elements out of title elements where they would cause trouble We could just as easily substitute this procedure with another that does something else to elements That is the beauty of this program it can be quickly re engineered to do any task on elements you want Here it is downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir sub fix iterms my SnodeRef shift test is this an indexterm return unless nodeRef nodeName eq indexterm test is the parent a title my SparentNodeRef nodeRef parentNode return unless parentNodeRef nodeName eq title If we get this far we must be looking at an indexterm inside a title Iherefore remove this indexterm and stick it just after the parent title SparentNodeRef g
400. nition or whatever makes it possible to mine data from the document to generate indexes glosse search tables and much more 3 2 3 Complex Structures Not all structures found in narrative documents can be so readily classified as blocks or inlines A table is really a block but an array of blocks An illustration has no character data so it can t be considered a blc Lists also have their own rules with indentation autonumbering or bullets and nesting Objects like the are necessary complications for the narrative model Handling these structures properly is a tricky subject but you can make some assumptions For one thir these structures usually remain inside the flow interrupting the surrounding text briefly It s as if the XN an ocean of narrative style markup broken up with little islands of complex markup Structures like figures and tables may float within the flow meaning that the formatter has some leeway placing the objects to produce the best page layout If a figure would cross a pagebreak in one place th formatter may be able to reposition it elsewhere For this reason such objects usually have captions wit references in the text that sound like the data is summarized in Table 3 5 A simple attribute like float yes may be sufficient to represent this capability in the markup Complex objects behave a little like blocks in that they are usually separated vertically from each other the surrounding text They may have some
401. niversity of Edinburgh in January 1998 this technical note put forth many of the features incorporated in W3C Schema and many others that were left out such as a mechanism for declaring entities and object oriented programming support Microsoft implemented a version of this calledXML Data Reduced XDR Document Content Description DCD I BM Microsoft and Textuality submitted this proposal in July 1998 as an attempt to integrate XML Data with the Resource Description Framework RDF It introduced the idea of making elements and attributes interchangeable Schema for Object Oriented XML SOX As the name implies this technical note was influenced by programming needs incorporating concepts as interfaces and parameters t was submitted in July 1998 by Veo S ystems Commerce One They have created an implementation that they use today Document Definition Markup Language DDML This proposal came out of discussions on the XML Dev mailing list It took the information expressed in a DTD and formatted it as XML leaving support for data types to other specifications Informed by these proposals the W3C XML Schema Working Group arrived at a recommendation in May 2001 composed of three parts XMLSO XMLS1 and XMLS2 named Primer Structures and Datatypes respectively Although some of the predecessors are still in use all involved parties downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir agreed tha
402. nking However it is now one star in a constellation of XML languages If you need to do more you can select other kinds of narre markup languages such as DocBook which we will discuss later in the chapter First let me clear up something that might be confusing to you use the terms HTML and XHTML interchangeably HTML is older than XML so its earlier incarnations do not follow all the rules of well for XML documents However XML was designed to make it as easy as possible to get HTML documents int good XML form HTML that is well formed XML is simply called XHTML From now on when use the ter HIML mean XHTML The best feature of HTML so great it s responsible for half of the acronym is hypertext text that span documents Where the Web is concerned the boundaries of documents are quite blurred As a result documents are typically small and with many nonlinear flows It s easy to get lost so navigation aids su links at the top bottom or margin are required But the basics blocks and inlines are the same as in X Example 3 4 is a short XHTML document I ve taken the content of a manual page for the Unix commant and reformatted it as HTML In this example pay attention to the blocks inlines and complex objects li lists Example 3 4 An XHTML document lt xml version 1 0 lt DOCTYPE html PUBLIC W3C DTD XHTML 1 0 Transitional EN http www w3 org TR xhtml11 DTD xhtmll transitional dtd SPECE lt head gt
403. nloaded from lib ommolketab ir The result of running a transformation with the above document and XSLT stylesheet is a formatted HTML page whitespace may vary So mE head rtitle Instructions Guide title head spodgu lt hl gt Instructions Guide lt hl gt lt h2 gt Parts lt h2 gt eu dt A dt lt dd gt fuselage left half lt dd gt lt dt gt B lt dt gt lt dd gt fuselage right half lt dd gt lt dt gt F lt dt gt lt dd gt steering fin lt dd gt lt dtSN lt at gt dad roeket nozzles dg dt C dt lt dd gt crew capsule lt dd gt othe lt h2 gt Steps lt h2 gt pie d 11 Glue fuselage left half Part A and fuselage right half Part B together to form the fuselage lt 7 iq lt li gt For each steering fin Part F apply glue and insert it into slots in the fuselage lt li gt lt 11 gt Affix rocket nozzle Part N to the fuselage bottom with a small amount of glue lt 11 gt lt 11 gt Connect crew capsule Part C to the top of the fuselage Do not use any glue as it is spring loaded to detach from the fuselage elg lt ol gt lt body gt lt html gt As you see here the elements in the source tree have been mapped to different elements in the result tree We have successfully converted a document in one format to another That is one example of XSLT in action Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Tea
404. nough to keep researchers busy for decades and making it one of the most successful science projects in history Of critical importance were the results of experiments designed to detect signs of life in the Martian Soil At the time most researchers considered the readings conclusive evidence against the prospect of living organisms on Mars A few however held that the readings could be interpreted in a more positive light In the late 1990 s when researchers claimed to have found tiny fossils in a piece of Martian rock from Antarctica they felt it was time to revisit the Viking experiment and asked NASA ti republish the results NASA staff retrieved the microfilm from storage and found it to be largely intact and readable They then began scanning the data intending to publish it on CD ROM This seemed like a simple task at first all they had to do was sort out the desired experiment data from the other information sent back from the space probes But therein lay the problem how could they extract specific pieces from a huge stream of munged information All of the telemetry from the landers came in a single stream and was stored the same way The soil sampling readings were a tiny fraction of information among countless megabytes of diagnostics engineering data and other stuff It was like finding the proverbial needle in a haystack To comb through all this data and extract the particular information of interest would have been immensely ex
405. ns as a pipeline very smooth a downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir As an example wrote the XSLT script in Example 1 12 Unlike Example 1 6 which transforms its sour HTML this transforms into XSL FO Notice the use of namespace qualifiers the element name parts to tl colons to distinguish between XSLT instructions and XSL FO style directives The elements that start wi XSLT commands and elements that start with o are formatting object tags Example 1 12 An XSLT stylesheet for telegram bound for FO lt xml version 1 0 encoding utf 8 lt xsl stylesheet version 1 0 xmlns xsl http www w3 org 1999 XSL Transform xmlns fo http www w3 org 1999 XSL Format gt lt xsl template match gt LO EOOL lt fo layout master set gt lt fo simple page master master name only gt fo region body region name xsl region body margin 1 0in padding 10pt gt lt fo region before region name 2 xsl region before extent 1 0in display align before gt fo region after region name xsl region after extent 1 0in display align after gt lt fo simple page master gt fo layout master set rto page sequence master reference only gt lt fo flow flow name xsl region body xsl apply templates JIIOs IIlOW fo page sequence SITO root lt xsl template gt lt xsl template match telegram gt lt fo block font size 18pt font family mono
406. nsert the replacement text at the time of parsing External entities must always be declared so the parser knows where to find the replacement text Ir the following example a document declares the three external entitieSspart1 amp part2 and amp part3 to hold its content lt xml version 1 0 gt CIDOCTYPE doc SYSTEM http www dtds r u us com generic dta SIBNTILY parrtl SrsrbM ol xmlt s SIBNTITT part2 SYSTEM 5 mLl CIBNILII parto SXSLIEM ps xsml IE SIOnegoc Spartl amp part2 SDAarLt5 lt Londgdocs As shown in Figure 2 20 the file at the top of the pyramid which we might call the master file contains the document declarations and external entity references The other files are subdocuments they contain XML but are not documents in their own right You could not legally downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir insert document prologs in them Each may contain more than one XML tree Though you can t validate them individually you can only validate a complete document any errors in a subdocumen will affect the whole External entities don t shield you from parse errors Figure 2 20 Document with external entities prolog o lt longdoc gt amp part1 s E ee plxmi amp pa rtz PEO amp part3 eM p2xmi lt longdoc gt S E 9 p3 xmil Whenever possible make each subdocument contain at most one XML tree While you can t valid
407. nt element 4 4 1 4 Nonelement content descriptors The text content descriptor is only one of several options for describing non element content Here s the full assortment ham a empty No content at all 000 es rateng eet poe eee O list A sequence of values The empty marker precludes any content With this declaration the elementbookmark is not allowed to appear in any form other than as an empty element lt element name bookmark gt lt empty gt lt element gt RELAX NG provides the value descriptor for matching a string of characters For example here is an enumeration of values for a size element lt element name size gt lt Ccho1ce gt lt value gt small lt value gt lt value gt medium lt value gt lt value gt large lt value gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt choice gt lt element gt By default value normalizes the string removing extra space characters The example element below would be accepted by the previous declaration eqn 7a gt Small lt si ze gt If you want to turn off normalization and require exact string matching you need to add a type string attribute The following declaration would reject the above element s content because of its extra space lt element name size gt lt choice gt lt value type string gt small lt value gt lt value type string gt medium lt value gt lt value type st
408. nts RFC documents 2045 through 2049 it includes a comprehensive list of known types and has inspired a registry for many more MIME was developed originally to extend the paradigm of email from plain text to a rich array of media Email transport systems such as the Simple Mail Transfer Protocol SMTP can only deal witt 7 bit ASCII text You cannot simply append a binary file to the end of a message and have it bounce happily across the Internet The data has to be encoded in an ASCII compatible way There are othei requirements as well such as a minimum line length and absence of certain control characters MIME introduces methods to transform data into a safe form It also describes how to package this data in a recognizable way for mail transfer agents and clients to work with One of the ways MIME describes a resource is by assigning it amedia type or content type which names the general category that best describes the data Each type includes a set of subtypes that exactly identify the resource The type and subtype are usually written together joined by a slash character For example image jpeg denotes a graphical resource in the JPEG format The major types include text Textual information that can be read in a traditional text editor without any special processing text plain IS as simple as you can get just ASCII characters without any kind of formatting other than whitespace image Graphical data requiring some display dev
409. o in on records withlightning speed 1 3 2 Format Documents mentioned before that a large class of XML documents are narrative meaning they are for human consumption But we don t expect people to actually read text with XML markup Rather the XML must be processed to put the data in a presentable form XML has a number of strategies and tools for turning the unappealing mishmash of marked up plain text into eye pleasing views suitable for web pages magazines or whatever you like Most XML markup languages focus on the task of how to organize information semantically That ts they describe the data for what it is not in terms of how it should look Example 1 2 encodes a mathematical equation but it does not look like something you d write on a blackboard or see in a textbook How you get from the raw data to the finished product is calledformatting 1 3 2 1 CSS There are a number of different strategies for formatting The simplest is to apply aCascading Style Sheet CSS to it This is a separate document not itself XML that contains mappings from element names to presentation details font style color margins and so on A formatting XMLprocessor such as a web browser reads the XML data file and the stylesheet then produces a formatted page by applying the stylesheet s instructions to each element Example 1 5 shows a typical example of a CSS stylesheet Example 1 5 A CSS stylesheet telegram display block bDacktcdroung O
410. o the type of document you re authoring If this document were a book for example it would look completely differei The metadata is specific to reference pages and even the sections are calledre secti meaning that tr are specific to a reference entry The types of inlines are much more numerous than in HTML with highly specific names likeoption command ahd citetitle The blocks too are more differentiated Notice that we now have asynopsi element to address a complaint made about the HTML example The tradeoffs of HTML are reversed here DocBook is much more complex and intricate than HTML mak harder to learn and use But the more specific vocabulary of this markup language makes it much more flexible in terms of formatting and processing With flexibility may come more work however since sorr will have to set up a big stylesheet to handle all the elements If you purchase a package solution as is possible with many high end XML editors much of this work may be done for you This example only shows a small part of DocBook I d like to give you another taste so that you can see breadth of its capabilities Example 3 6shows a more traditional narrative document a book Here you see a wide variety of section elements chapters sections and complex structures table figure list A the example I ve made notes to explain some of the elements Example 3 6 A DocBook book lt xml version 1 0 encoding utf 8 gt lt DOCTY
411. oaded from fib ommolkcefab ir Team LiB 1 2 Where Did XML Come From XML is the result of a long evolution of data packaging reaching back to the days of punched cards I is useful to trace this path to see what mistakes and discoveries influenced the design decisions 1 2 1 History Early electronic formats were more concerned with describing how things should look presentation than with document structure and meaning troff and TEX two early formatting languages did a fantastic job of formatting printed documents but lacked any sense of structure Consequently documents were limited to being viewed on screen or printed as hard copies You couldn t easily writ programs to search for and siphon out information cross reference information electronically or repurpose documents for different applications Generic coding which uses descriptive tags rather than formatting codes eventually solved this problem The first organization to seriously explore this idea was the Graphic Communications Association GCA In the late 1960s the GenCode project developed ways to encode different document types with generic tags and to assemble documents from multiple pieces The next major advance was Generalized Markup Language GML a project by IBM GML s designers Charles Goldfarb Edward Mosher and Raymond Lorie intended it as a solution to the problem of encoding documents for use with multiple information subsystems Documents coded in
412. objects into pages paragraphs graphics and other presentational components The process is illustrated inFigure 1 4 Figure 1 4 How XSL works downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Source document Temporary F driver file XSLT stylesheet The source document on the left is first transformed using an XSLT stylesheet and XSLT processor into a formatting object tree using XSLT This intermediate file is then fed into the XSL formatter which processes it into a presentational format such as PDF The beauty of this system is that it is modular You can use any compliant XSLT processor and XSL formatter You don t need to know anything about the presentational format because XSL is so generic describing layout and style attributes in the most declarative form will describe XSL in more detail inChapter 8 1 3 2 4 Programming solutions Finally if stylesheets do notfit the bill which may be the case if your source data is just too raw for direct transformation then you may find a programming solution to be to your liking Although XSLT has much to offer in transformation it tends to be rather weak in some areas such as processing character data often find that despite my best efforts to stay inside the XSLT paradigm sometimes have to resort to writing a program that preprocesses my XML data before a transformation Or may have to write a program that does the whole processing from sou
413. ocessing It also may serve as a way to formalize anapplication being a publishable object that describes a language in unambiguous rules 1 Technically schemas validate on an element by element and attribute by attribute basis It is possible to test a subtree alone for validity and determine that parts are valid while others are not This process is rather complex and beyond the scope of this book 4 1 1 Validation An XML schema is like a program that tells a processor how to read a document It s very similar to a later topic we ll discuss called transformations The processor reads the rules and declarations in the schema and uses this information to build a specific type of parser called a validating parser The validating parser takes an XML instance as input and produces a validation report as output At a minimum this report is a return code true if the document is valid false otherwise Optionally the parser can create a Post Schema Validation Infoset PSVI including information about data types and structure that may be used for further processing Validation happens on at least four levels Structure The use and placement of markup elements and attributes Data typing Patterns of character data e g numbers dates text ntegrity The status of links between nodes and resources Business rules Miscellaneous tests such as spelling checks checksum results and so on Structural validation is the most important and
414. ocument chose to revisit Example 3 6 It s long enough to span several pages and contains some complex objects such as tables lists and footnotes And as a bonus it includes chapters and sections with titles that need to be differentiated stylistically Figure 8 11 is a screenshot of a page with a variety of block and inline areas There is a section head on the top left an inline style on the top right a program listing on the bottom and a paragraph in the middle The paragraph contains a footnote marker Figure 8 11 A screenshot of the middle of the page Figure 8 12 shows the bottom of the same page At the top of the screenshot is the body of the footnote previously mentioned It is at the bottom of the body flow Under it is the static flow area of the footer which contains a generated page number and the chapter title Figure 8 12 A screenshot of a footer In Figure 8 13 we see a close up of a table The table header area is shaded gray with bold text downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Figure 8 13 A screenshot of a table able 2 1 lists the function of the parts labeled in the diagram Tale 2 1 Contra Descriptions Control Purpose Decoy Power Switch Looks just like an on off toggle button but only turns on a small flashlight when pressed Very handy when yOLIT SONIC Screwdriver 9000 is misplaced and discovered by primitive aliens who might otherwise accidentally injure
415. ocument elementrss is a channel element giving a general overview of the site In it we find e Descriptive text including a short title and longer paragraph e Administrative details contact information link to the main page copyright e Language identifier en us which means that it uses the American variant of English more about language encodings in Chapter 9 e Time of last update using a standard time format RFC 822 recognized all over the Internet After the channel comes a series of elements describing each item in the site This example has two a text document and a sound file Each has a correspondingitem element containing a text description link to the resource and the date it was posted downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The sound file has an additional element enclosure which provides some details about the format The type attribute gives the content type audio mp3 The format of this description comes from the Multipurpose Internet Mail Extensions standard RFC 2046 For more about RSS see Ben Hammersley s Context Syndication with RSS O Reilly amp Associates 2003 3 4 2 Templates Describing documents is also thejob of the transformation language XSLT But in this case we re talking about documents in thefuture XSLT generates new documents from old ones following rules in a transformation stylesheet For each element in the source document there will b
416. ode for editing XML and SGML documents that is available at http www lysator liu se lenst SAX Information on SAX the Simple API for XML is available athttp www saxproject org Here you will find the Java source code and some helpful documentation Xalan A high performance XSLT stylesheet processor that fully implements XSLT and XLinks You can find out more about it at the Apache XML Project web site http xml apache org Xerces A fully validating parser that implements XML DOM levels 1 and 2 and SAX2 Find out more about it at the Apache XML Project http xml apache org XT A Java implementation of XSLT at http www jclark com xml xt html Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB A 5 Miscellaneous User Friendly Illiad Starring the formidably cute dust puppy and a gaggle of computer industry drones this comic Strip will inject much needed jocularity into your bloodstream after a long day of hacking XML The whole archive is available online athttp www userfriendly org and in two books published by O Reilly User Friendly the Comic Strip and Evil Geniuses in a Nutshell The Cathedral and the Bazaar Eric S Raymond O Reilly amp Associates In this philosophical analysis and evangelical sermon about the grassroots open source computer programming movement Raymond extols the virtues of community sharing and that warm feeling you
417. ode itself After the axis comes a node test parameter joined to the axis by a double colon A name can be used in place of an explicit node type in which case the node type is inferred from the axis For the attribute axis the node is assumed to be an attribute and for the namespace axis the node is assumed to be a namespace For all other axes the node is assumed to be an element In the absence of a node axis specifier the axis is assumed to bechild and the node is assumed to be of type element Table 6 2 lists the node tests Preceding Table 6 2 Node tests Term Matches The root node not the root element but the node containing the root element and any comments or processing instructions that precede it Matches any node For example the step attribute node would select all the attributes of the context node n In the attribute axis any attribute In the namespace axis any namespace In all other axes any element node In the attribute axis the attribute named crabcake of the context crabcake node In a namespace axis it s a namespace calledcrabcake In all other axes any element named crabcake text Any text node processing eee An processing instruction processing A l ny processing instruction with target for web instruction for web y P J E comment Any comment node Location path steps are chained together using the slash character Each step gets
418. of CSS1 and part of CSS2 DOMI DOM2 and part of DOM3 Microsoft nternet Explorer Microsoft has tried very hard to play ball with the open standards community and it shows with th XML parsing is excellent along with strong support for DTDs XSLT CSS1 SVG with plug in an Strangely Internet Explorer is split into two completely different code bases with versions for Windows Macintosh independent from each other This has led to wacky situations such as the Mac version being more advanced than its Windows cousin The best versions and perhaps last available are 6 0 on Wind for Macintosh Mozilla 1 4 Mozilla is an open source project to develop an excellent free browser that supports all the major Mozilla s heart is a rendering engine code named Gecko that parses markup and churns out forrr It s also the foundation for Netscape Navigator and IBM s Web Browser for OS 2 How is it for compliance Mozilla fully supports XML using James Clark s Expat parser a free and I tool Other standards it implements include HTML 4 XHTML CSS1 CSS2 SVG with plug in XSL XPath MathML with plug in RDF and Unicode Some standards are only partially supported su XLink and CSS3 For more information about XML in Mozilla go to the Web at http mozilla org newlayout xml Netscape Navigator downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir As of version 6 Navigator has been based on the Mozilla browsers
419. of an element name 1 followed by some number of attribute tests 2 in square brackets which in turn contain an attribute name 3 and value 4 Note that only an element or attribute is required The other parts are optional The element name can contain wildcards to match any element and it can also contain chains of elements to specify hierarchical information The attribute tests can check for the existence of an attribute with any value the existence of a value for any attribute or in the strictest case particular attribute value combination Figure 5 7 Syntax for a CSS selector 5 3 1 Elements Matching an element is as simple as writing its name emphasis Lonr stile Italic font weight bold This rule matches any emphasis element in the document This is just the tip of the iceberg There are many ways to qualify the selection You can specify attribute names attribute values elements that come before and after and even special conditions such as whether the cursor is currently hovering over a link or in what language the document claims to be written A list of names is also allowed letting you apply the same properties to many kinds of elements Here a set of three properties applies to any of the four elements name phone email and address name phone email address display type block margin top 2em margin bottom 2em downloaded from lib ommolketab ir downloaded from fib o
420. of declarations that defines the names of the elements and their attributes and specifies rules for their combination and sequence See alsodocument document type declaration Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB E editor A software program that packages your keystrokes into files to author text on a computer one must use an editor Some editors are fancier than others The simplest isvi an old but still kicking Unix editor Emacs is a nice editor with lots of configuration potential but a somewhat steep learning curve and no style presentation Both of these editors display the text and markup together which can make authoring difficult for those who aren t used to seeing all the tags in the content See also document markup element A defined piece of an XML document XML elements are denoted by start and end tags and car contain data and other elements in a specified hierarchy See alsoattribute content markup empty element An element that is comprised of a single tag and contains no content data An empty element begins with an opening angle bracket followed by the element name any attributes and their values and closed with a slash and closing angle bracket See also attribute content element entity A name assigned by means of declaration to some chunk of data Some entities have been predefined for special characters such as
421. of document complete stopping renderer The numbers in brackets represent the number of the page being rendered once the FO tree has been constructed If this process doesn t work there could be several reasons First the source document may not be well formed and you will see output like this INFO FOP 0 20 4 ERROR The markup in the document preceding the root element must be well formed Check the files with a parser to rule out this possibility Second the XSLT stylesheet may have an error It may not be well formed XML or it may be invalid XSLT structurally Here misspelled an element name in the XSLT and got a cryptic error message INFO FOP 0 20 4 ERROR nuli Check all the elements in the xs1 namespace to make sure it is valid You might want to test it with an XSLT engine that has verbose output to see where in the file the error occurs xsltproc from gnome org has very good parse error messages Third the formatting object tree may contain invalid markup INFO FOP 0 20 4 INFO building formatting object tree ERROR Unknown formatting object http www w3 org 1999 XSL Format robot ERROR java lang NullPointerException This occurred because changed the name of a formatting object fromfo root to fo robot Although FOP s error messages aren t the easiest to read at least it did manage to tell me that it wa a formatting object naming problem Team LIB downloaded from lib ommolketab ir do
422. ok s web site at http www oreilly com catalog learnxml2 Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Comments and Questions We have tested and verified the information in this book to the best of our ability but you may find that features have changed or even that we have made mistakes Please let us know about any errors you find as well as your suggestions for future editions by writing to O Reilly amp Associates Inc 1005 Gravenstein Highway North Sebastopol CA 95472 800 998 9938 in the United States or Canada 707 829 0515 international or local 707 829 0104 fax We have a web page for this book where we list errata examples or any additional information Yot can access this page at http www oreilly com catalog learnxml2 To comment or ask technical questions about this book send email to bookquestions oreilly com You can sign up for one or more of our mailing lists at http elists oreilly com For more information about our books conferences software Resource Centers and the O Reilly Network see our web site at http www oreilly com You may also write to the author directly at etr ravelgrane com Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Acknowledgments wish to thank my reviewers Jeni Tennison Mike Fitzgerald and Jeff Maggard for
423. ology helps to divide the vast space of UCS Arow is 256 characters Wherever possible an 8 bit character set is stuffed into a single row For example ISO Latin 1 inhabits the first row positions 0x0000 to OxOOFF 121 256 rows 65 534 characters is called a plane Most of Unicode lives in the first plane 0x0000 to OxFFFD also called the Basic Multilingual Plane BMP though recent versions have moved beyond that set 2 The syntax OxNNNN is used to represent a hexadecimal number This is a base 16 system convenient for representing integers in systems based on powers of 2 It s more convenient than decimal because it can be easily divided by powers of 2 merely by shifting the decimal point Since character encoding domains are frequently based on powers of 2 will frequently use hexadecimal numbers to describe code positions UCS Unicode assigns to each character in the BMP a code number which is the string U and four hexadecimal numbers and a formal name The number for A isu 0041 and its name is Latin capital letter A In ASCII it would be Ox41 and the same in ISO Latin 1 Converting between these character sets is not difficult once you know the base number in UCS In addition to defining the character ordering the Unicode Standard includes semantics related to issues such as sorting string comparison handling leftward and rightward scripts and mixing together bidirectional scripts UCS in contrast is not much more than a
424. om lib ommolketab ir downloaded from fib ommolkcefab ir eJ include sstart lt ref name report gt lt start gt lt grammar gt This is a good way to customize a schema to suit your own particular taste 4 4 8 CensusML Example In case you are curious let s go back to the CensusML example from Section 4 3 and try to do it as a RELAX NG schema The result is Example 4 10 Example 4 10 A RELAX NG schema for CensusML lt element name census record gt smlne httos J relaxng org nse strucLure l1 9 datatypeLibrary http www w3 org 2001 XMLSchema datatypes lt attribute name taker gt data type integer gt lt param name minInclusive gt 1 lt param gt lt param name maxInclusive gt 9999 lt param gt lt data gt Jattruibute element name date gt data type date gt lt element gt lt element name address gt lt interleave gt lt element name street gt lt text gt lt element gt lt element name city gt lt text gt lt element gt lt element name county gt lt text gt lt element gt lt element name postalcode gt data type string gt lt param name pattern gt 0 9 0 9 0 9 A Z A Z A Z lt param gt lt dava gt lt element gt lt interleave gt lt element gt lt oneOrMore gt lt element name person gt lt interleave gt lt attribute name employed gt lt choice gt lt value gt fulltime lt value gt lt value gt parttime lt
425. om the head Example 3 8 A molecule definition in MoDL lt xml version 1 0 lt modl gt lt head gt lt meta name title content Water gt DEFINE name Hydrogen atom radius 0 2 color 1 1 0 J gt lt DEFINE gt lt DEFINE name Oxygen gt atom radius 0 5 color 1 0 1 gt lt DEFINE gt lt head gt lt 00ay gt atom id HO type Hydrogen position 1 0 0 atom id H1 type Hydrogen position 0 0 1 atom id O type Oxygen position 0 1 0 pond stomle o atom H0 color 0 0 1 Jj bond atoml 0 atom25 Hl color 0 0 I lt body gt lt modl gt For each atom instance there is an element describing its type position and a unique identifier e g HO for the first hydrogen atom Each bond between atoms also has its own element specifying color and the two atoms it joins Notice the interplay betweenatoms and bonds The unique identifiers in the first group are the hooks for the second group which use attributes that refer to them Unique identifiers are another invaluable technique in expressing relationships betwee concepts MoDL is a project by Swami Manohar and Vijay Chandru of the Indian Institute of Science The goal i not just to model molecules but to model their interactions The language contains elements to express motion as well as the static initial positions Elements can represent actions applied to molecules including translate and rotate
426. om the census example here is how you would define thecounty element xs schema xmlns xs http www w3 org 2001 XMLSchema lt xs element name county type xs string gt lt xs schema gt The xs element element acts like an ELEMENT declaration in a DTD Its name attribute declares a name county and itStype attribute defines a content model by referring to adata type identifier Instead of using a compact string of symbols to define a content model schemas define content models in a separate place then refer to them inside the element definition This is kind of like using parameter entities but as we will see it s more flexible in schemas xs string refers to a simple type of element one that is built in to the Schema specification In this case it s just a string of character data about as simple as you can get An alternative toxs string IS xs token It also contains a string but normalizes the space strips out leading and trailing space and collapses extra space characters for you Table 4 1 lists other simple types which are commonly used in schemas There are many more types in W3C XML Schema Part 2 Datatypes but this core covers most frequent needs and will get you started downloaded from lib ommolketab ir downloaded from lib ommolketab ir Table 4 1 Simple types commonly used in schemas Type Usage SSiecring Contains any text xs token Contains textual tokens separated by whitespace
427. ommolkcefab ir 10 11 12 ol element which formats with numbers The formatter will generate numbers automatically so yc don t need to know how to count The systemitem Inline element is rather generic allowing for several types of system item incluc computer domain names URLs FTP sites and more It s a good idea to give sections ID attributes Later you may want to make a cross reference to o them Remember that each ID attribute must have a unique value A comment element allows you to insert a message that is not part of the narrative and will be rerr before the final revision of the document is formatted It s better than an actual XML comment obj because it can be included in formatting for a draft printout This element constructs a figure consisting of a title and an empty element that imports a graphic The xref element is a cross reference to another element in the document The formatter will deci based on the type of element referenced what to put in its place In this case the object is a table we might expect to see something like Table 3 1 Here is another complex object a table DocBook s DTD doesn t define this element directly but instead imports the definition from another DTD an XML application called CALS Continuous Acquisition and Life Cycle Support CALS was a Department of Defense project that made early us SGML to improve its documentation The CALS table model is very flexible and robu
428. ommolkcetftab ir Team LiB A B C D E F G IH 1 J K L EM EN O P IQ R S T U V W X files flat structures floats flows mappin narrative documents objects 2nd top level elements following siblings fonts 2nd See also text properties sizing 2nd style weight footnotes for each element foreign languages See also Unicode characters formatting specifying formatting documents elements foreign language graphics inlines messages objects page layout transformation printing XSL FO areas DocBook formatters objects overview of page layout printing processing TEI XML XSLT 2nd FPI formal public identifier fragment identifiers 2nd fully qualified names functions lang node set downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir numeric strings XPointer Team LiB downloaded from lib ommolketab ir downloaded from lib ommolketab ir Team LIB A B C D E F EG H 1 J K L M EN O P IQ R S T U V W X generated content inline formatting generated text glyphs areas grammars merging nested graphics inline formatting standards SVG types of grouping Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LIB A B C D E IF G IH 1 J K L EM EN O P Q R S T U V W X heads
429. on abou what was imported from where is lost before the DTD is parsed There are a few ways to get around this problem You can override entity declarations by redeclaring them or to be more precise predeclaring them In other words if an entity is declared more than once the first declaration will take precedence So you can override any entity declaration with a declaration in the internal subset of your document since the internal subset is read before the external subset Overriding an element declaration is more difficult It is a validity error to declare an element more than once You can make multiple ATTLIST declarations for the same element and the first one is accepted as the right one So the question is how can you override a declaration such as this lt ELEMENT polyhedron sidet anglet gt with a declaration of your own like this lt ELEMENT polyhedron side side side angle angle anglet gt To be able to override element and attribute declarations is not possible with what you know so far need to introduce you a new syntactic construct called the conditional section 4 2 4 5 Conditional sections A conditional section is a special form of markup used in a DTD to mark a region of text for inclusion or exclusion in the DTD L4 If you anticipate that a piece of your DTD may someday be an unwanted option you can make it a conditional section and let the end user decide whether to keep it or not Note that c
430. onal paragraph whose style has been modified to look like a code listing In our example there is only one line of code but what would happen if there were more The whitespace would be crushed into single spaces and the code would lose its structure So perhaps a better definition would be based on thepre element Figure 5 15 shows how the CSS formatted page would look in a web browser Figure 5 15 Browser view of the XHTML document downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Navigator File Edit View Go Baokrearks Aui Help NM m oe ee Tue 2 048 PH l a e CATT Skis Canara Casmanid i Maia B a oe FP oS fie leche Sle ary nechani La a2 im a CAT 1 System General Commands Manual SYNOPSIS nmt bancor filse DESCRIPTION The usliny es Hes vequec ni ally Siig Loo bo the ted eed cei The file opersedi ac pART N CAE ne er A anale Co pes ibe mee ol Tbe apid dre an Polen f nglizi Uae 5 apipi bot dpeuit urrbes hlaik lies Decgemest Dane basii i ka m m P bg oe BOLI cod 1 Aptian T Fl Btylkl csB 2 DSPm D 5r Tet Fillj L3i Ttrs a x jo a a gt ud 21 aC E cu This example is fairly simple due to the fact that every browser has a built in stylesheet for HTML so we are in fact only overriding a few default properties We should now take a look at how a CSS stylesheet would look for another kind of XML document Let s return to Examp
431. onalization Section 9 1 Character Encodings Section 9 2 MIME and Media Types Section 9 3 Specifying Human Languages Chapter 10 Programming Section 10 1 Limitations Section 10 2 Streams and Events Section 10 3 Trees and Objects Section 10 4 Pull Parsing Section 10 5 Standard APIs Section 10 6 Choosing a Parser Section 10 7 PYX Section 10 8 SAX Section 10 9 DOM Section 10 10 Other Options Appendix A Resources Section A 1 Online Section A 2 Books Section A 3 Standards Organizations Section A 4 Tools Section A 5 Miscellaneous Appendix B A Taxonomy of Standards Section B 1 Markup and Structure Section B 2 Linking Section B 3 Addressing and Querying Section B 4 Style and Transformation Section B 5 Programming Section B 6 Publishing Section B 7 Hypertext Section B 8 Descriptive Procedural Section B 9 Multimedia Section B 10 Science Glossary A Im o IO W p i qm a downloaded from fib ommolkceftab ir downloaded from fib ommolkcefab ir x S IC IFA M I Jo lv O Iz Ix Colophon Index Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Copyright Copyright 2003 2001 O Reilly amp Associates Inc Printed in the United States of America Published by O Reilly amp Associates Inc 1005 Gravenstein Highway North Sebastopol CA 95472 O Reilly amp Associates books may be purchased for educational
432. ond is for more advanced settings The XML declaration used has to be the first line in the document Example 2 1shows a document containing a full prolog 2 Don t confuse document type declaration with document type definition a completely different beast To keep th two terms distinct will always refer to the latter one with the acronym DTD Example 2 1 A document with a full prolog lt xml version 1 0 standalone no gt The XML declaration lt I DOCTYPE Beginning of the DOCTYPE declaration reminder Root element name SYSTEM home eray reminder dtd DTD identifier Internal subset start delimiter lt ENTITY smile lt graphic file smile eps gt gt Entity declaration l gt Internal subset end delimiter lt reminder gt Start of document element amp smile Reference to the entity declared abo lt msg gt Smile It can always get worse lt msg gt lt reminder gt End of document element 2 3 1 The XML Declaration The XML declaration is a smallcollection of details that prepare an XML processor for working with a document It is optional but when used it must always appear in the first line Figure 2 3shows the forn it takes It starts with the delimiter xm1 1 contains a number of parameters 2 and ends with the delimiter 3 Figure 2 3 Form of the XML declaration Each parameter consists of a name an equals sign and a quoted value Theversion parameter mu appear if the other parameters a
433. onditional sections can be used only in external subsets not internal subsets 41 n SGML you can use conditional sections in documents as well as in DTDs XML restricts its use to DTDs only personally miss them because think they are a very powerful way to conditionally alter documents Conditional sections look similar to CDATA sections They use the square bracket delimiters but the CDATA keyword is replaced with either INCLUDE or IGNORE The syntax is like this switchlDTD text gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir where switch Is like an on off switch activating the DTD text if its value is INCLUDE or marking it inactive if it s set to IGNORE For example lt INCLUDE lt these declarations will be included SIBLEMENT foo bar Caz buDi lt ATTLIST foo crud CDATA IMPLIED gt i lt IGNORE these declarations will be ignored gt lt ELEMENT blah PCDATA gt lt ELEMENT l p flub zuc 2zuc gt gt Using the hardcoded literals INCLUDE and IGNORE isn t all that useful since you have to edit each conditional section manually to flip the switch Usually the switch is a parameter entity which can be defined anywhere CIBNIITT OprLionel sSturr TICLE lt z0ption l stuff these declarations may or may not be included gt STELEMENT foo bar Caz bub 7 lt ATTLIST foo crud CDATA IMPLIED gt
434. ontains shapes labels structures and protects information It does this with symbols embedded in the text called markup Markup enhances the meaning of information in certain ways identifying the parts and how they relate to each other For example when you read a newspaper you can tell articles apart by their spacing and position on the page and the use of different fonts for titles and headings Markup works in a similar way except that instead of spaces and lines it uses symbols Markup is important to electronic documents because they are processed by computer programs If e document has no labels or boundaries then a program will not know how to distinguish a piece of text from any other piece Essentially the program would have to work with the entire document as a unit severely limiting the interesting things you can do with the content A newspaper with no space between articles and only one text style would be a huge uninteresting blob of text You could probably figure out where one article ends and another starts but it would be a lot of work A computer program wouldn t be able to do even that since it lacks all but the most rudimentary pattern matching skills XML s markup divides a document into separate information containers calledelements Like Tupperware containers they seal up the data completely label it and provide a convenient package for computer processing Like boxes elements nest inside other elements One bi
435. ood stylesheet editing interface that lets you play around styles almost as easily as creating a template in a word processor Structure enforcement can be anothe since you may have to create a document type definition DTD from scratch Like a stylesheet the DTE editor how to handle elements and whether they are allowed in various contexts You may decide that tl work is worth it if it saves error checking and complaints from users down the line Editors often come with interfaces for specific types of markup XML Spy includes many such extensions you to create and position graphics write XSLT stylesheets create electronic forms create tables in a s builder and create XML Schema Tables found in XML applications like HTML and DocBook are comple and believe me when tell you they are not fun to work with in markup To have a specialized table edit godsend Another nicety many editors provide is automatic conversion to terminal formats FrameMaker Epic an all generate PDF from XML This high quality formatting is difficult to achieve however and you will spe time tweaking difficult stylesheets to get just the appearance you re looking for There is a lot of variatic editors in how this is achieved XML Spy uses XSLT while Epic uses FOSI and FrameMaker uses its own mapping tables Generating HTML is generally a lot easier than PDF due to the lower standards for docui viewed on computer displays so you will see more editors that can conver
436. ore of a higher level conceptual testing pattern rather than as a specific node matching pattern The context for each test is determined by arule Its context attribute contains an XSLT pattern that matches nodes Each node found becomes thecontext node on which all tests inside the rule are applied The children of a rule report and assert each apply a test to the context node The test is another XPath expression stored in a test attribute report s contents will be output if its XPath expression evaluates to true assert Is Just the opposite outputting its contents if its test evaluates to false downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XPath expressions are very good at describing XML nodes and reasonably good at matching text patterns Here s how you might test an email address Tule cgontexre amairc lt p gt Found an email address lt p gt lt assert test contains gt Error no in email lt assert gt lt eaSsSer Test Con agains SError no dot i0 enmallc asssert report test length gt 20 gt Warning email is unusually long lt report gt lt rule gt To summarize running a Schematron validator on a document works like this First parse the document to build a document tree in memory Then for each rule obtain a context node using its XPath locator expression For each assert Or report in the rule evaluate the XPath expression for a Boolean v
437. ou write will require such intimate knowledge of byzantine rules and obscure conventions that it will quickly lead to madness Believe me I ve done it Fortunately somebody has had the brilliant idea to develop a formatting language based on plain Englis for its structural markup XSL FO the cousin of XSLT uses the same terminology as CSS to describe ty inline styles blocks margins and all the concepts you need to create a nice looking page You can look FO document and easily see the details for how it will be rendered You can edit it directly and it won t b your face Best of all it works wonderfully with XSLT In the XSL process see Figure 1 4 you give the XSLT transformer a stylesheet and an input document an XSL FO document that contains the data plus style information A formatter takes the XSL FO instan renders that into a terminal format like PDF which you can print or view on a computer screen AlthougF edit the XSL FO directly it s unlikely you would want to do that Much better would be to edit the origin or the XSLT stylesheet and treat the XSL FO as a temporary intermediate file In fact some implementa even output the XSL FO unless you request it My favorite XSL FO formatter is called FOP Formatting Object Processor and it s a project of the prodic XML Project http xml apache org fop FOP is written in Java and comes bundled with a Java based Xerces and a Java based XSLT transformer Xalan The whole thing ru
438. p www jdom org Microsoft Schema XPath XML XML Java C C Schema definition http msdn microsoft com xml Parser language XSD Schema Object Model SOM DTD validation SAX2 PyXML Python DOM2 PullDOM http pyxml sourceforge net Xparse JavaScript Basic stream parser http www jeremie com Dev XML Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 7 PYX PYX is an early XML stream solution that converts XML into character data compatible with text applications like grep awk and sed Its name represents the fact that it was the first XML solution in the programming language Python XML events are separated by newline characters fitting nicely into the line oriented paradigm of many Unix programs Table 10 2 summarizes the notation of PYX Table 10 2 PYX notation Symbol Represents An element start tag An element end tag Character data A An attribute A processing instruction For every event coming through the stream PYX starts a new line beginning with one of the five event symbols This line is followed by the element name or whatever other data is pertinent Specia characters are escaped with a backslash as you would see in Unix shell or Perl code Here s how a parser converting an XML document into PYX notation would look The following code is XML input by the parser shooprsnglisto lt l
439. pabilities of DTDs Schema uses valid XML to declare elements and attributes for structuring a document and alsc provides extensible facilities for defining datatypes of elements and attributes RELAX NG A simpler schema language OASI S I SO Status RELAX NG became an OASIS Technical Committee Specification in December 2001 It is published at http www oasis open org committees tc home php wg abbrev relax ng RELAX NG is also part of the ISO Document Structure Description Language DSDL Information about that project can be found at http www dsdl org Description RELAX NG defines a schema language for describing XML document structures RELAX NG has a mathematical basis similar to regular expressions making it easy to process as well as both an XML based syntax and a human friendly compact syntax RELAX NG defines only structural components for datatyping RELAX NG schemas typically depend on W3C XML Schema Schematron An extremely flexible schema language I SO Status Schematron is an ongoing community project and its most recent definition is published at http www ascc net xml resource schematron Schematron is also part of the ISO Document downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Structure Description Language DSDL Information about that project can be found at http www dsdl org Description Schematron uses tools from XSLT and XPath to define an extremely
440. pan gt at the end of each line as well dd lt dt gt lt span class option n span dt downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir lt dd gt Number the output lines starting at 1 lt dd gt lt dt gt lt span class option s span dt lt dd gt Squeeze multiple adjacent empty lines causing the output to be single spaced lt dd gt dt span class option gt t lt spaen gt lt dt gt ggg Implies the span class option v span option and displays tab characters as span class symbol gt I lt span gt as well dd lt dt gt lt span class option uc span dt lt dd gt The span class option gt u lt span gt option guarantees that the output is unbuffered lt dd gt lt dt gt lt span class option v span dt dd Displays non printing characters so they are visible Control characters print as span class symbol X span for control X the delete character octal 0177 prints as span class symbol 5 span Non ascii characters with the high bit set are printed as span class symbol gt M lt span gt for meta followed by the character for the low 7 bits lt 7 da gt lt dl gt 5s The lt i gt cat lt i gt utility exits 0 on success and amp gt 0 if an error occurs es QU Haus div class section lt h2 gt BUGS lt h2 gt P Because of the shell language mechanism used to perform o
441. parser A validating parser works by comparing a document against a set of rulescalled a document model One kind of document model is a document type definition DTD It declares all the elements that are allowed in a document and describes in detail what kind of elements they can contain Example 1 7is a small DTD for telegrams Example 1 7 A telegram DTD lt ELEMENT telegram from to subject graphic message gt lt ATTLIST telegram pri CDATA IMPLIED gt lt ELEMENT from PCDATA gt lt ELEMENT to PCDATA gt lt ELEMENT subject PCDATA gt lt ELEMENT graphic EMPTY gt lt ATTLIST graphic fileref CDATA REQUIRED gt lt ELEMENT message PCDATA emphasis name villain gt lt ELEMENT emphasis PCDATA gt lt ELEMENT name PCDATA gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Before submitting the telegram document to a parser need to add this line to the top lt DOCTYPE telegram SYSTEM location of dtd gt Where location is the path to the DTD file on my system Now can run a validating parser on the telegram document Here s the output get gt xval exl memo xml exl memo xml 13 validity error No declaration for element villain mastermind villain Dr Indigo Riceway lt villain gt exl memo xml 15 validity error Element telegram content doesn t follow the DTD lt telegram gt Oops forgot to declare the villain element
442. pattern breaking up the schema into discrete parts that are more easily handled It also allows for reusing patterns that recur in many places A schema that uses named patterns follows this layout lt grammar gt LOCAT main pattern eJstart define name identifier gt pattern define more pattern definitions lt grammar gt The outermost grammar element encloses both the main pattern and a set of named pattern definitions It contains exactly one start element with the primary pattern and any number of define elements each defining a named pattern Named patterns are imported into a pattern using a ref element For example grammar xmlns http relaxng org ns structure 1 0 SOLO DL element name report ref name head gt lt ref name body gt lt element gt setari define name head gt lt element name title gt text lt element gt lt element name authorname gt lt text gt lt element gt lt defin ne gt lt define name body gt lt zZz amp ro0rMore gt element name paragraph text lt element gt lt zeroOrMore gt lt define gt lt grammar gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The start element must contain exactly one pattern However adefine may contain any number of children since its contents will be copied into another pattern You can write a grammar to fit the style of DTDs with one de
443. pending on where it occurs 5 3 3 1 Ancestry You can specify that an element is a child of another element using the greater than symbol 6e For example book gt title font size 24pt chapter gt title i font size 20pt title font size 18pt The element to select here istitie If the title appears in a book then the first rule applies If it appears within a chapter the second rule is chosen If the title appears somewhere else the last rule is used The gt operator works only when there is one level separating the two elements To reach an element at an arbitrary depth inside another element list them in the selector separated by spaces For example table para color green Dare 1 Color Diack The first rule matches a para that occurs somewhere inside a table like this downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt table gt lt title gt A plain ol table lt title gt SLUUPOHD SLOQUV row Sentry lt para gt Hi I m a table cell paragraph lt para gt There s no limit to the number of elements you can string in a row This is useful if you ever need to go far back into the ancestry to gather information For example say you want to use a list inside a list perhaps to create an outline By convention the inner list should be indented more than the outer list The following rules would provide you with up to three levels of nested lists list indent
444. pensive and time consuming It would require detailed knowledge of the probe s data communication specifications which were buried in documents that were tucked away in storage or perhaps only lived in the heads of a few engineers long since retired Someone might have to write software to split the mess into parallel streams of data from different instruments All the informatior was there It was just nearly useless without a lot of work to decipher it Luckily none of this ever had to happen Someone with a good deal of practical sense got in touch with the principal investigator of the soil sampling experiment He happened to have a yellowing cop of the computer printout with analysis and digested results ready for researchers to use NASA only had to scan this information in and republish it as it was without the dreaded interpretation of aging microfilm This story demonstrates that data is only as good as the way it s packaged Information is a valuable asset but its value depends on its longevity flexibility and accessibility Can you get to your data easily Is it clearly labeled Can you repackage it in any form you need Can you provide it to others without a hassle These are the questions that the Extensible Markup Language XML was designed to answer Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Preface Since its introduction in the late 90s Extensible Markup L
445. pic There we ll go into deeper detail about the picky rules and describe some new components you haven t seen yet You ll then be able to tear apart any XML document and know what all the piecesare for and put together documents of your own 1 1 2 A Markup Language Toolkit Strictly speaking XML is not a markup language A language has a fixed vocabulary and grammar but XML doesn t actually define any elements Instead it lays down a foundation of syntactic constraints on which you can build your own language So a more apt description might be to call downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir XML a markup language toolkit When you need a markup language you can build one quickly using XML s rules and you ll be comfortable knowing that it will automatically be compatible with all the generic XML tools out there The telegram in Example 1 1 is marked up in a language invented for fun chose a bunch of element names that thought were important to represent a typical telegram and a couple that were gratuitously silly like villain This is okay because the language is for my use and can do whatever want with it Perhaps have something in mind for thevillain element like printing it in a different color to stand out The point is that XML gives me the ability to tailor a markup language any way want which is a very powerful feature 1 1 2 1 Well formedness Because XML doesn t have a pr
446. pplication of the computer system arc An abstract term for the relationship between a link in a document and its target See also resource simple link ASCII American standard code for information interchange Pronounced ASK ee this venerable standard describes a set of 128 characters used to display text When early computer development was taking place in the United States this was sufficient for all textual needs However larger character sets such as Unicode which contain downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir letters symbols and ideographs for virtually all of the world s languages are now more common Still ASCII will be around for a long time UTF 8 is a new character set based on ASCII that includes methods for referencing any Unicode character See alsocharacter encoding character set attribute A variable or term that defines a specific setting or provides additional information to an element Attributes appear as name value pairs contained in an element s start tag See also element markup Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B block element A block of text or content such as a paragraph title or section that is separated from other text by whitespace See alsoinline element box model A CSS stylesheet concept used for formatting block elements The box model forms a boundary
447. presentation in one place rather than doing a global search and replace operation in the XML If you don t like one stylesheet you can swap it for another And you can use the same stylesheet for multiple documents Keeping style out of the document enhances your presentation possibilities since you are not tied to a single style vocabulary Because you can apply any number of stylesheets to your document you can create different versions on the fly The same document can be viewed on a desktop computer printed viewed on a handheld device or even read aloud by a speech synthesizer and you never have to touch the original document source simply apply a different stylesheet It is of course possible to create presentation vocabularies in XML XSL FO is an excellent example In XSL FO s case however its creators expect developers to create XSL FO through XSLT stylesheets not directly downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Keep it simple For XML to gain widespread acceptance it had to be simple People don t want to learn a complicated system just to author a document XML 1 0 is intuitive easy to read and elegant It allows you to devise your own markup language that conforms to some logical rules It s a narrow subset of SGML throwing out a lot of stuff that most people don t need Simplicity also benefits application development If it s easy to write programs that process XML files there wil
448. pshot of xemacs with an XML document open Figure 1 5 Highlighted markup in xemacs with psgml downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Morphon Technologies XMLEditor is a fine example of a graphical user interface As you can see in Figur window sports several panes On the left is an outline view of the book in which you can quickly zoom I particular element open it collapse it and move it around On the right is a view of the text without m below these panes is an attribute editing pane The layout is easy to customize and easy to use Note th in the text view achieved by applying a CSS stylesheet to the document Morphon s editor sells for 15 can download a 30 day demo at http www morphon com It s written in Java so it supports all compu platforms downloaded from lib ommolketab ir Ho grammar rulest term An element can contain anythingBmdash mixed content elements or text mdash or it can be empty pars listitem f v arlistentry gt that this is true Ho restrictions on attributes t tern Any element can contain any attribute However attributes from the xmi 4r Literal namespace retain their special properties attributes primary default behavior without document model secondary l indexternm xml namespace preflx lt orimary indextenprm Cal para All attributes are treated as type COATA literal character data This means that
449. pt you ll see that it is a no fooling around programming language The syntax is Scheme a dialect of Lisp You have to be a pretty good programmer to be able to work witl it and the parentheses might drive some to distraction There is really nothing you can t do with DSSSL but for most transformations it may be overly complex certainly don t miss it As XML gained prominence the early adopters and developers began to map out a strategy for high quality formatting They looked at DSSSL and decided it suffered from the same problems as SGML too big too hard to learn not easy to implement James Clarke a pioneer in the text processing frontier who was instrumental in DSSSL development took what he had learned and began to work on a slimmed down successor Thus was born the Extensible Stylesheet Language XSL XSL is really three technologies rolled into one e XPath for finding and handling document components e XSL Transformations for changing any XML document into a presentational XSL Formatting Object tree e XSL Formatting Objects a markup language for high quality formatted text XSL Transformations XSLT is the subject of this chapter we already covered XPath in the last chapter and visit XSL Formatting Objects in the next First published as a recommendation by the W3C in 1999 it was originally designed just to transform an XML document into an XSL Formatting Object tree hence the reason why it retains the XSL in i
450. pts Section 2 1 Tags Section 2 2 Documents downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Section 2 3 The Document Prolog Section 2 4 Elements Section 2 5 Entities Section 2 6 Miscellaneous Markup Chapter 3 Modeling Information Section 3 1 Simple Data Storage Section 3 2 Narrative Documents Section 3 3 Complex Data Section 3 4 Documents Describing Documents Chapter 4 Quality Control with Schemas Section 4 1 Basic Concepts Section 4 2 DTDs Section 4 3 W3C XML Schema Section 4 4 RELAX NG Section 4 5 Schematron Section 4 6 Schemas Compared Chapter 5 Presentation Part CSS Section 5 1 Stylesheets Section 5 2 CSS Basics Section 5 3 Rule Matching Section 5 4 Properties Section 5 5 Examples Chapter 6 XPath and XPointer Section 6 1 Nodes and Trees Section 6 2 Finding Nodes Section 6 3 XPath Expressions Section 6 4 XPointer Chapter 7 Transformation with XSLT Section 7 1 History Section 7 2 Concepts Section 7 3 Running Transformations Section 7 4 The stylesheet Element Section 7 5 Templates Section 7 6 Formatting Chapter 8 Presentation Part Il XSL FO Section 8 1 How It Works Section 8 2 A Quick Example Section 8 3 The Area Model Section 8 4 Formatting Objects Section 8 5 An Example TEI Section 8 6 A Bigger Example DocBook downloaded from fib ommolkefab ir downloaded from fib ommolkceftab ir Chapter 9 Internati
451. purple font family sans serif Frontestyles italic font weight bold downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir j command font family monospace font weight bold color red j SODEIOBD 1 font family monospace font weight bold color blue j SVIBDOX 4 font family monospace font weight bold color green used the body element as the stage for setting global properties All the viewable elements will inherit these properties and optionally override them The remaining rules are divided into the block type element group and rules for inline elements In the block group the rule matching section will apply to all the lt div class section gt elements separating the page into nicely separated regions using background color and margin settings Heads are next with the elements ni n2 and n3 set to override the font family of the page with sans serif This is an example of how a rule can match a group of elements and apply the same set of styles to each An interesting experiment to try is to add a font size property setting for one of these heads You ll probably find that no matter what you set it to it will not change the size of the text in most HTML browsers am not sure why this is the case but it is an example of how the user agent can choose to ignore the style settings from the server Skip down to the rule matching code This is a traditi
452. quote gt lt xsl template gt lt xsl template match emphasis gt lt i gt lt xsl apply templates gt lt i gt lt xsl template gt lt xsl template match name gt lt font color blue gt lt xsl apply templates gt lt font gt lt xsl template gt lt xsl template match villain gt lt font color red gt lt xsl apply templates gt lt font gt lt xsl template gt lt xsl template match graphic gt lt img width 100 gt xsl attribute name src gt lt xsl value of select fileref gt lt xsl attribute gt lt img gt lt xsl template gt lt xsl transform gt When applied against the document in Example 1 1 this script produces the following HTML Figure 1 3 shows how it looks in a browser chemi lt head gt meta content text html charset UTF 8 http equiv Content Type lt title gt telegram lt title gt lt head gt lt body gt lt div style background color wheat padding lem gt lt hl1 gt telegram lt h1 gt lt h2 gt to Sarah Bellum lt h2 gt lt h2 gt from Colonel Timeslip lt h2 gt lt h2 gt subj Robot sitting instructions lt h2 gt blockquote font style font family monospace gt Thanks for watching my obot pal lt font color blue gt Zonky lt font gt while I m away He needs to be recharged lt i gt twice a day lt i gt and if he starts to get cranky give him a quart of oil I ll be back soon after I ve tracked down that evil mastermind font co
453. r extent 0 5in co downloaded from lib eommolketab ir downloaded from fib ommolkcefab ir lt fo simple page master gt Notice how had to choose distinctive names for the page masters as well as the regions inside them except for the body regions Why not name the body regions They get the implicit namexs1 region body Which is good enough because the text will flow inside it the same way no matter what the page type 8 6 2 Page Sequence Masters Now we define the page sequence masters Well there is only one sequence When first wrote this example had two One was used for chapters and another for front matter The front matter includes dedication preface foreword and other junk at the beginning of the book The distinction was necessary because these pages are typically numbered with Roman numerals and the page count resets to 1 at the first chapter However this example was so large it would have caused many trees to die unnecessarily for the extra pages did the right green thing and left it out The sequence master uses a repeatable page master alternatives FO to hold a reference for each of the possible page types Remember there are four of them Theconditional page master reference FO has attributes page position and odd or even to determine which page type to select lt xsl template name page sequence masters gt lt fo page sequence master master name chapter initial page number 1 form
454. r document can refer to although parts of DTDs can also reside inside your document A DTD is a collection of rules or declarations describing elements and other markup objects An element declaration adds a new element type to the vocabulary and defines itscontent model what the element can contain and in which order Any element type not declared in the DTD is illegal Any element containing something not declared in the DTD is also illegal The DTD doesnt restrict what kind of data can go inside elements which is the primary flaw of this kind of document model 1 1 2 4 Schemas Schemas are a later invention offering moreflexibility and a way to specify patterns for data which is absent from DTDs For example in a schema you could declare an element calledaate and then require that it contains a legal date in the format YYYY MM DD With DTDs the best you could do is say whether the element can contain characters or elements Unfortunately there is a lot of controversy around schemas because different groups have put forth competing proposals Perhaps there will always be different types of schemas which isfine with me 1 1 3 An Open Standard As Andrew Tanenbaum a famous networking researcher once said The wonderful thing about standards is that there are so many of them We ve all felt a little bewildered by all the new standards that support the information infrastructure But the truth is standards work and without them the world
455. racter is to precede it with a circumflex As the circumflex is the escaping character it too must be escaped if it appears on its own Simply precede it with another circumflex If the xpointer is to be used inside a URI reference then you need to respect the character escaping rules laid out in IETF RFC 2396 In this scheme certain characters are represented with a percent symbol and a hexadecimal number For example a space character would be replaced by 20 and a percent symbol by 225 Here is an xpointer before escaping xpointer string range para I use parentheses a lot You must at minimum escape it like so downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir xpointer string range para I use parentheses a lot If the xpointer appears in an URI reference some other characters need to be escaped including the circumflexes xpointer string range para I 20use 20parentheses 220 5E a 2010t 5E 6 4 4 XPointer Functions XPointer inherits from XPath all the functions and tests defined in that recommendation To that set i adds a few specific to points and ranges 6 4 4 1 Constructing ranges The function range to creates a range starting from the context node and extending to the point given as its argument In other words it creates a range from the last step to the next step For example suppose you have a document that defines index terms that each spans severa
456. ration already in the DID However the next line switches off a conditional section by declaring the parameter entityprice module to be IGNORE SO the DTD s declaration will be hidden from the parser The last declaration overrides an external parameter entity in the DTD that imports a module causing it to load the file myfigs mod instead You re only allowed to declare an element once in a DTD so while you can override declarations for attributes don t declare an element in the internal Subset if it s already declared elsewhere 4 2 5 SimpleDoc A Narrative Example In Section 4 2 3 we developed a simple DTD for a data markup language Narrative applications tend to be a little more complex since there is more to human languages than simple data structures Let s experiment now with a DTD for a more complex narrative application Inspired by DocBook I ve created a small narrative application called SimpleDoc It s much smaller and doesn t attempt to do even a fraction of what DocBook can do but it touches on all the major concepts and so is suitable for pedagogical purposes Specifically the goal of SimpleDoc is to mark u small simple documents such as the one in Example 4 3 Example 4 3 A sample SimpleDoc document lt xml version 1 0 gt CIDOCIYTPE doo SYSIENM simoledoc dgbEd SUDO downloaded from lib ommolketab ir downloaded from lib ommolketab ir lt title gt Organism or Machine lt title gt section
457. rce to presentational format That option is always available and we will see it in detail inChapter 10 1 3 3 Ensure Data Integrity Trust is important for data trust that it hasn t been corrupted truncated mistyped or left incomplete Broken documents can confuse software format as gibberish and result in erroneous calculations Documents submitted for publishing need to be complete and use only the markup that you specify Transmitting and converting documents always entails risk that some information may be lost XML gives you the ability to guarantee a minimal level of trust in data There are several mechanisms First there is well formedness Every XML parser is required to report syntax errors In markup Missing tags malformed tags illegal characters and other problems should be immediately reported to you Consider this simple document with a few errors in it lt announcement lt lt TEXT gt Hello world I m using XML amp it s a lot of fun lt Text gt lt anouncement gt When I run an XML well formedness checker on it here is what get gt xwf t xml downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir t xml 2 error xmlParseEntityRef no name lt TEXT gt Hello world I m using XML amp it s a lot of fun lt Text gt t xml 2 error Opening and ending tag mismatch TEXT and Text lt TEXT gt Hello world I m using XML amp it s a lot of fun lt Text gt t xml 3 error Opening and
458. rd University Press A complete reference for SGML including an annotated specification Like its subject the book is complex and hefty so beginners may not find it a good introduction Java and XML 2nd Edition Brett McLaughlin O Reilly amp Associates A guide to combining XML and Java to build real world applications SAX2 David Brownell O Reilly amp Associates A complete guide to using the SAX2 API in Java Processing XML with J ava Elliotte Rusty Harold Addison Wesley A guide to building programs using a variety of Java techniques for processing XML XML and Java Hiroshi Murayama et al Addison Wesley Explores many different aspects and APIs of Java processing with XML Java XML Data Binding Brett McLaughlin O Reilly amp Associates A guide to processing XML with data binding approaches covering APIs which insulate developers from the XML Perl and XML Erik Ray and Jason Mclntosh O Reilly amp Associates A guide to processing XML with a variety of Perl based approaches Python and XML Christopher A Jones and Frederick Drake O Reilly amp Associates A guide to processing XML in Python programs NET and XML Niel Bornstein O Reilly amp Associates A guide to processing XML using the Microsoft NET API Building Oracle XML Applications Steve Muench O Reilly amp Associates A detailed look at Oracle tools for XML development and how to combine the power of XML an XSLT with the functionality o
459. re used downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir version Declares the version of XML used At the moment only version 1 0 is officially recognized but version 1 1 may be available soon encoding Defines the character encoding used in the document If undefined the default encoding UTF 8 o UTF 16 if the document begins with the xFEFF Byte Order Mark will be used which works fine fo most documents used in English speaking countries Character encodings are explained in Chapte standalone Informs the parser whether there are any declarations outside of the document As explain in th next section declarations are constructs that contribute information to the parser for assembling and validating a document The default value is no setting it to yes tells the processor there a no external declarations required for parsing the document It does not as the name may seem ti imply mean that no other resources need to be loaded There could well be parts of the documen other files Parameter names and values are case sensitive The names are always lowercase Order is important t version must come before the encoding which must precede the standalone parameter Either single or double quotes may be used Here are some examples of XML declarations lt i 2 lt xml version 1 0 gt lt xml version 1 0 encoding US ASCII standalone yes gt lt xml version 1 0 encoding 1iso 885
460. region body lt fo simple page master gt fo layout master set fo page sequence master reference the only page type gt lt fo flow flow name xsl region body xsl apply templates lt Tori low lt fo page sequence gt dec huoo ub lt xsl template gt 1 Make the article a box with a quarter inch of padding inside gt lt xsl template match article gt SION font family times serif font size 12pt padding 0 25in border solid lpt black xsl apply templates lt Ot block lt xsl template gt The title has no spacing properties gt lt xsl template match title gt CIOILOCK font weight bold text align center xsl apply templates erToi5xLosk lt xsl template gt l A para has a set of space Constraints minimum Of 2 points maximum of 4 points and ideal of 3 points I added a silver border for reference lt xsl template match para gt SIOIDILOOGR Space before minimum 2 0pt Space before optimum 3 0pt Space before maximum 4 0pt Space after minimum 2 0pt Space after optimum 3 0pt Space after maximum 4 0pt downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir border solid lpt silver text align left xsl apply templates Jio block lt xsl template gt lt xsl stylesheet gt Figure 8 7 shows how it looks when formatted Figure 8 7 The article formatted Batten Down the Hatches
461. resembles a tree with the outermost element and its contents branching out to the innermost text which are like leaves Tree processing as we call it a long lasting representation of the document s data and markup It requires more memory and comput often the most convenient way to accomplish a task Developers have come up with standard programming interfaces for each of these techniques The Sime XML SAX specifies how a parser should interact with a program for stream processing This allows proc interchangeable modules greatly enhancing flexibility It s possible to writedrivers programs that simul but get their input data from databases or non XML formats and know that any SAX enabled program v handle it This is illustrated in Figure 1 13 Figure 1 13 SAX makes programs modular and interchangeable What SAX does for stream processing the Document Object Model DOM does for tree processing It d wide variety of accessor methods for objects containing parts of an XML document With DOM you can the elements in a document in any order rearrange them add or subtract parts and extract any data y Many web browsers have built in support for DOM allowing you to select and repackage information fro using Java or JavaScript SOAP is a way for browsers to trade complex data packages with servers Unlike HTML which marks up on appearance it describes its contents as data objects with types names and values which is much n downloaded
462. ric values They are used for chapter numbers ordered lists and anything else that needs to be labeled with a number To use a counter you have to give it a name and tell CSS when to increment it using the propertycounter increment You can get the value of the counter any time with the counter function For example chapter counter increment chapnum chapter gt title before content Chapter counter chapnum Here we create a counter called chapnum and increment it every time the CSS processor sees a new chapter The title element is rendered with this number just before it like this Chapter 3 Sonic the Hedgehog counter reset IS another property that affects counters It sets the counter value back to zero wher the element is processed This can be used for things like numbered lists where you want each list t start at 1 instead of incrementing through the whole document numberedlist counter reset list item number j listitem counter increment list item number listitem before content counter list item number Now each list will start counting at 1 First list 1 Alpha 2 Bravo 3 Charlie 4 Delta Second list 1 Fee 2a BU JS FO 4 Fum Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 5 5 Examples Let s put what we know to use now and format a document with CSS XHTML is a good place to start so let s take the
463. ring gt large lt value gt lt choice gt lt element gt The most interesting content descriptor is data This is the vehicle for using datatypes in RELAX NG Its type attribute contains the name of a type defined in a datatype library Don t worry about what that means yet we ll get to it in a moment The content of the element declared here is set to be ar integer value lt element name font size gt lt data type integer gt lt element gt One downside to using data is that it can t be mixed with elements in content unliketext The list descriptor contains a sequence of space separated tokens A token is a special type of string consisting only of nonspace characters Token lists are a convenient way to represent sets of discrete data Here one is used to encode a set of numbers lt element name vector gt E E we lt oneOrMore gt lt data type float gt lt oneOrMore gt SISSE lt element gt Here is an acceptable vector vector gt 44 034 19 0 65 33333 lt vector gt Note how the oneOrMore descriptor works just as well with text as it does with elements It s yet another example of how succinct and flexible RELAX NG is 4 4 2 Data Typing downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Although RELAX NG supports datatyping the specification only includes two built in types string and token To use other kinds of datatypes you need to import them from anoth
464. ring wheel gas and brake pedals and so on You do not have to know anything about the engine itself such as how many cylinders are firing and in what order Just as you never have to fire the spark plugs manually you should never have to write your own XML parser unless you want to do something really unusual Linking to another developer s parser is a good idea not just because it saves you work but because it turns the parser into a commodity By that mean you can unplug one parser and plug in another Or you could unplug a parser and plug in a driver from a database or some real time source XML does not have to come from files after all None of this would be possible however without the use of standard APIs This chapter will demonstrate a few examples of this For event streams the standard is SAX DOM i a standard for object tree interfaces Most programming languages have a few conforming implementations of each When possible it is always a good idea to use SAX or DOM Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 6 Choosing a Parser After choosing your programming strategy SAX DOM XMLPULL etc the next step in writing an XML application is to select a parser There is no reason to write your own parser when so many excellent ones already exist Some qualities to look for are API support speed and efficiency and robustness Table 10 1 lists some of t
465. ring a transmission UTF 8 encoding is optimized for common Western characters The lower a character s position in the Unicode UCS pool the shorter its encoded string of bytes While UTF 8 characters can theoretically be as long as 6 bytes those in the BMP portion of UCS will be at most 3 bytes long Many European scripts will be just 2 bytes in length and all ASCII characters only 1 byte If there is any disadvantage to using UTF 8 it is that non Western scripts are penalized with longer characters and increased document size downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 9 1 4 4 UTF 16 UTF 16 is closely related to UTF 8 using a similar transformation algorithm to get from Unicode positions to numeric sequences In this case the sequences consist of 16 bit integers not bytes As with UCS 2 and UCS 4 byte Is an issue you have to take into account Some systems will use a BOM byte order mark and be able to detect byte order automatically You can also explicitly select a byte order by using the more specific encoding nameUTF 16LE low endian or UTF 16BE big endian This encoding is one of the two required encodings all proper XML parsers must support In reality a few handle UTF 8 but not UTF 16 as 16 bit support for characters is not yet a universal feature in programming languages Perl for example is moving that way but some legacy parsers still are not there This concludes my list of most
466. ring local String raw throws SAXException if product equals local index else if name equals local catalog index name cdata toString else if price equals local catalog index price cdata toString else throw new SAXException Unexpected element local j The program maintains a little bit of state information in the form of an index variable As this counte increments it stores data from the next product in the next slot Thus it builds a growing list of products in its catalog array At first glance this program seems to be adequate It will handle a data file that is valid but if you throw some bad markup at it it will do strange things Imagine what would happen if you gave it this data file catalog CorodHct 1g9 dgridgsbpve l225 lt name gt Woofinator lt name gt CIDPOSUGL lt price gt 8 77 lt price gt lt catalog gt Oops The price element is not inside the product like it should be The program we wrote will not catch the mistake Instead it will save the product data for the woofinator without a price then increment the index When the parser finally reaches the price it will be too late to insert into the product slot Clearly this ought to be a validation error but our program is not smart enough to catch it To protect against problems like this we could add a test for a missingprice element or an extra one outside the product element But then we would
467. rings expressions TREX Tree Regular Expressions for XML troubleshooting CS5 pull parsing resources books online standards organizations tools type defining typeface types of entities of expressions of graphics of media of nodes of schemas 2nd DTDs RELAX NG downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir W3C XML Schema of tags Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LiB A B C D E F G H 1 J K L EM N O P IQ R S T U V W X UCS Universal Multiple Octet Coded Character Set UCS 2 UCS 4 Unicode Unicode characters 2nd references Unicode Consortium web site unique identifiers units of measurement Universal Multiple Octet Coded Character Set UCS Unix operating systems text editors unparsed entities URIS namespace maintainer or version URLs relative schemes US ASCII character sets user stylesheets UTF 16 UTF 8 2nd UTF 8 character encoding Team LIB downloaded from fib ommolkcetftab ir downloaded from lib ommolketab ir Team LIB A B C D E F G IH 1 J K L EM N O P IQ R S T U V W X validation DTDs parsers schemas 2nd validity values counters dictionaries nodes outputting variables counters XSLT versions tracking vi text editor viewing documents nodes Team LiB download
468. rint a message End of document Print the number of elements counted Start of element Output the qualified name of the element the namespace URI and the number of attributes End of element Increment the element counter and print a message Any other events are handled by the superclassDefaultHandler We run the program on the data in Example 10 4 Example 10 4 Contents of text xml lt xml version 1 0 gt bcb breakfast cereal box xmlns bcb http www grubblythings com gt lt bcb name gt Sugar Froot Snaps lt bcb name gt lt bcb graphic file bcbcover tif gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir bcb prize Decoder ringc bcb prize bcb breakfast cereal box The full command is java Dorg xml sax driver org apache xerces parsers SAXParser oAXCounter test xml The D option sets the property org xml sax driver to the Xerces parser This is necessary because my Java environment does not have a default SAX driver Here is the output Starting to parse Starting element bcb breakfast cereal box namespace http www grubblythings com number of attributes O0 CDATA 3 characters Starting element bcb name namespace http www grubblythings com number of attributes O0 CDATA 17 characters ending element bcb name CDATA 3 characters Starting element bcb graphic namespace http www grubblythings com number of attributes 1 ending elem
469. rite software for DTDs and Schema are available tc check for missing information and they provide an easy way to distinguish between versions Are there limitations Of course XML is not so good when it comes to raster graphics This category of graphics formats which includes TIFF GIF and JPEG renders an image based on pixel data Instead of a conceptual representation based on shapes it s a big fat array of numbers You could store this in XML certainly but the benefits of markup are irrelevant since elements would only downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir increase the document s size without organizing the data well Furthermore these formats typically use compression to force the huge amount of data into more manageable sizes something markup would only complicate Video presents similar larger problems What other concepts are ideally suited to XML representation How about chemicals Every molecule has a unique blueprint consisting of some combination of atoms and bonds Languages like the Chemical Markup Language CML and Molecular Dynamics Language MoDL follow a similar strategy to encode molecules Example 3 8 shows how a water molecule would be coded in MoDL Notice the separation ofhead and body that is reminiscent of HTML The head is where we define atomic types giving them size and color properties for rendering The body is where we assemble the molecule using definitions fr
470. rize the set and choose a particular article from it Making matters worse not all documents have the capability to describe themselves such as sound and graphics files To address these problems a class of documents evolved that specialize in describing other documents To fully describe different kinds of documents these markup languages have some interesting features in common They list the time documents have been updated using standard time formats They label the content type be it text image sound or something else They may contain text descriptions for a user to peruse For international documents they may track the language encodings Also interesting is the way documents are uniquely identified using a physical address or some nonphysical identifier 3 4 1 Describing Media Rich Site Summary or Really Simple Syndication depending on whom you talk to was created by Netscape Corp to describe content on web sites They wanted to make a portal that was customizable allowing readers to subscribe to particular subject areas orchannels Each time they returned to the site they would see updates on their favorite topics saving them the trouble of hunting around for this news on their own Thus was born the service known ascontent aggregation Since the time when there were a few big content aggregators like Netscape and Userland the landscape has shifted to include hundreds of smaller more granular services Instead of subscribing
471. rmation is included stu cruft has exactly the same priority as stuff because they both specify hierarchical information about the node 4 A pattern with a successful test expression in square brackets overrides a pattern with no test expression but that is otherwise identical SObobo role clown has higher priority than bobo Again this only works when no hierarchical information is included circus bobo and circus bobo role clown have the same priority 5 Other information such as position in the stylesheet may be used to pare down the set if there is still more than one rule remaining The basic assumption is that rules that are more specific in their application take precedence over rules that are more general If this were not the case it would be impossible to write catch all rules and default cases Position and order don t come into play unless all other means of discrimination fail It s up to the transformation processor to determine how to handle the final tie breaking downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The xsl template element has an optional priority attribute that can be set to give it precedence over other rules and override the process of determination The value must be a real number i e it must have a decimal point unless it is zero and can be positive negative or zero A larger number overrides a smaller number 7 5 3 Default Rules XSLT defines a se
472. rocessor is required to support both UTF 8 and UTF 16 Other encodings are optional so you enter that territory at your own risk downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 9 1 2 Basic Concepts The atomic unit of information in XML is the character A character can be a visible symbol such as the letters on this page or a formatting code like the ones that force space between words and separate lines in paragraphs It may come from a Latin script or Greek Thal or Japanese It may be a dingbat or punctuation mark Most generally a character is any symbol with possibly different representations whose meaning is understood by a community of people Every character belongs to a finite ordered list called acharacter set also called a coded character set It is really not a set in the mathematical sense but more of a sequence or table Perhaps the best description according to Dan Connolly in his article Character Set Considered Harmful H is to think of it as a function whose domain is a subset of the integers and whose range is a set of characters In other words give the function a positive integer orcode position and it will give you back a character from that place in its character repertoire 1 Read it on the Web at http www w3 org MarkUp html spec charset harmful html The earliest character set in common use is the American Standard Code for Information Interchange US ASCII al
473. rom someone else importing their DTD into your own as a subset Or you may just want to make the DTD a little neater by separating pieces into different files To import whole DTDs or parts of DTDs use an external parameter entity Here is an example of a complete DTD that imports its pieces from various modules lt ELEMENT catalog title metadata front entriest gt lt 1ENTITY X DSsSlOSturr SYSTEM bastocs mog downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir basic stuff lt 1ENTITY front matter SYSTEM Ironc mod f ront matter ENTITY metadata PUBLIC Standards Stuff DTD Metadata v3 2 EN http www standards stuff org dtds metadata dtd Smetadata This DTD has two local components which are specified by system identifiers Each component has a mod filename extension which is a traditional way to show that a file contains declarations but Should not be used as a DTD on its own The last component is a DTD that can stand on its own in fact in this example it s a public resource There is one potential problem with importing DTD text An external parameter entity importsall the text in a file not just a part of it You get all the declarations not just a few select ones Worse there is no concept of local scope in which declarations in the local DTD automatically override those in the imported file The declarations are assembled into one logical entity and any informati
474. round color PTT downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir term float left variablelist margin top 0 5em margin bottom 0 5em margin left lem margin right lem INLINES citetitle command keysym literal option manvolnum replaceable display inline command keysym literal option font family monospace font weight bold citetitle font style italic command bacsdgrounds Gray color Diack keysym background purple color yellow literal color brown manvolnum before content manvolnum after Gombtenbts Tas j Option qv color blues Jj refmeta before content replaceable font style italic Every element in this example has itSdisplay property set Although the default behavior in browsers is to set the display to inline think it s a good idea to be explicit and set them all lest you forget If you want to see how a document looks when everything is an inline try taking out the display property settings Can you say obfuscated Notice that in this example took advantage of CSS s property merging feature to make things a little more organized All the inline elements have their display property set in one rule and any other specific properties are added in other rules Skip down to the rule matching re synopsisdiv before Here s an example of generated text As downloaded from lib ommo
475. rs gt or candy bar id mars gt butnot planet id venus gt Remember that only one element in the whole document can have an ID attribute with a given value so this rule is very specific planet uninhabited An attribute that is frequently used to designate special categories of an element for stylesheets is class A shortcut for matching class attributes is the period which stands for class The selector above matches planet class uninhabited gt but doesn t match planet class colony gt planet lang en This selector form is used to match elements with a particular language specified In pre XML versions of HTML language would be specified in alang attribute In XML the attribute is xml lang The attribute values are matched in the same way as with the operator a hyphenated item is a match if its name begins with a string identical to the one in the selector The xm1 1ang attribute is an exception to XML s usual rules of case sensitivity values here are compared without regard to case So in this example the selector matches lt planet lang en gt planet lang EN us gt OF planet lang en US gt but not planet lang jp gt 5 3 3 Contextual Selection Selectors can also use contextual information to match elements This information includes the element s ancestry its parent its parent s parent etc and siblings and is useful for cases in which an element needs to be rendered differently de
476. rt taking up only one page Clearly this lack of a challenge is an insult to any self respecting XSL formatter So let us set our sights on something more challenging Let us return to our old friend DocBook for inspiration We will include support for most of the common elements you would find in technical prose including some objects we have not covered yet such as tables lists and footnotes To flex the muscles of pagination we will also explore the use of different page masters and conditional master sequences To save you from having to look at a huge monolithic listing I ll break up the stylesheet into manageable chunks interspersed with friendly narrative 8 6 1 Page Masters We will start by setting upthe page masters This is a very verbose piece of the stylesheet since we want to create a page master for each type of page chose to cover these types l Lefthand verso page starting a chapter It happens to have an even numbered page number which we will use to identify it in the page sequence master The layout will include a header that shows the chapter title and number and a body that is pushed down further than a non starting page 2 Righthand recto page starting a chapter The main difference is that its page number is odd and the header is right justified instead of justified on the left 3 Verso page that does not start a chapter It has a plain header and body that reaches up almos to the top 4 Recto p
477. rted into a string then the string conversion rule is used Boolean The value true is converted to the number 1 and false to the number O Stri If the string is the literal serialization of a number i e 123 5 it is converted i into that number Otherwise the value NaN is used Result tree Like node sets a result tree fragment is converted into a string which is then fragment converted with the string rule To manipulate numeric values there are a variety of operators and functions These are cataloged in Table 6 11 Table 6 11 Numeric operators and functions Function Returns expr expr The Sum of two numeric expressions expr expr The difference of the first numeric expression minus the second expr expr The product of two numeric expressions downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Function Returns Tr n The value of the expression rounded up to an integer value sum node The sum of the values of the nodes in node set Unlike the other functions in this set table this function operates over a nodeset instead of expressions 6 3 4 String Expressions A string is a segment of character data such as How are you 990 or z Any expression can be converted into a string using the string function following the rules in Table 6 12 Table 6 12 Rules to convert expressions into strings Expression type Rule Node set The te
478. rts to get cranky give him a quart of oil I ll be back soon after I ve tracked down that evil mastermind villian Dr Indigo Riceway lt villian gt t message telegram gt Inside element start tags you sometimes will see some extra characters next to the element name Ir the form of name value These are attributes They associate information with an element that may be inappropriate to include as character data In the telegram example earlier look for an attribute in the start tag of thetelegram element Declarations are never seen inside elements but may appear at the top of the document or in an external document type definition file They are important in setting parameters for the parsing session They define rules for validation or declare special entities to stand in for text The next three objects are used to alter parser behavior while it s going over the document Processing instructions are software specific directives embedded in the markup for convenience e g storing page numbers for a particular formatter Comments are regions of text that the parser should strip out before processing as they only have meaning to the author CDATA sections are special regions in which the parser should temporarily suspend its tag recognition Rounding out the list are entity references commands that tell the parser to insert predefined pieces of text in the markup These objects don t follow the pattern of other tags in th
479. ruction gt Comment Comments are also omitted from the result tree by default lt xsl template match comment 7 5 4 Redirecting Processing The template model of transformation creates islands of markup separate from each other We need downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir some way of connecting them so that processing continues through the document According to the default rules for every element that has no matching template the XSLT engine should output its text value This requires processing not only its text nodes but all the descendants in case they have text values too If a template does match an element it is not required to do anything with the element or its content n fact it is often the case that you want certain elements to be ignored Perhaps they contain metadata that is not to be included with the formatted data So you are allowed to leave a template empty Here the element ignore me will be passed over by the XSLT processor unless another rule matches with higher priority lt xsl template match ignore me gt Unless you explicitly tell the XSLT engine how to proceed with processing in the template it will go n further Instead it will revert to the context node set and evaluate the next node in line If you do want processing to go on to the children or you want to insert other nodes to process before the next node in the context set there are som
480. ruly useful some principles of generic coding had to be sacrificed For example one document type was used for all purposes forcing people to overload tags rather than define specific purpose tags Second many of the tags are purely presentational The simplistic structure made it hard to tell where one section began and another ended Many HTML encoded documents today are so reliant or pure formatting that they can t be easily repurposed Nevertheless HTML was a brilliant step for the Web and a giant leap for markup languages because it got the world interested in electronic documentation and linking To return to the ideals of generic coding some people tried to adapt SGML for the Web or rather to adapt the Web to SGML This proved too difficult SGML was too big to squeeze into a little web browser A smaller language that still retained the generality of SGML was required and thuswas born the Extensible Markup Language XML 1 2 2 The Goals of XML Dissatisfied with the existingformats a group of companies and organizations began work in the mid 1990s at the World Wide Web Consortium W3C on a markup language that combined the flexibility of SGML with the simplicity of HTML Their philosophy in creating XML is embodied by several important tenets Form should follow function In other words markup languages need to fit their data snugly Rather than invent a single generic language to cover all document types badly let there be
481. s Entity references included in this data will be resolved See alsoCDATA parsed character data parsed character data Any character data that should be checked by the XML processor for entity references These references are resolved and their replacement text parsed recursively to replace all entity references See also PCDATA parser A software program that reads XML validates it and passes it on for further processing If a document is not well formed i e there s an error in the markup the parser catches it and reports the problem See also markup XML processor physical structure The physical organization of data in a file as opposed to its document or logical structure An object oriented database for example is a physical structure that doesn t align with its logical structure See also document logical structure presentation The appearance of a document that has been formatted for human consumption See also stylesheet processing instruction A markup object that conveys information to a specific XML processor It has the form target data where target is a keyword to alert a particular processor and data Is a text string containing the special information Any processor that doesn t recognize the processing instruction ignores it downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir properties declaration The part of a stylesheet rule that sets the formatting for the
482. s down readily into hierarchical containers suct as chapters sections and paragraphs Less obvious are the models for equations molecules and downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir databases For such applications it takes a supple mind to chop up documents into the optimal mix of elements and attributes These tips are principles that can help you design DTDs e Choose names that make sense If your document is composed exclusively of elements like thing object and chunk it s going to be nearly impossible to figure out what s what Names Should closely match the logical purpose of an element It s better to create specific elements for different tasks than to overload a few elements to handle many different situations For example the DIV and SPAN HTML elements aren t ideal because they serve many different roles e Hierarchy adds information A newspaper has articles that contain paragraphs and heads Containers create boundaries to make it easier to write stylesheets and processing applications And they have an implied ownership that provides convenient handles and navigation aids for processors Containers add depth another dimension to increase the amount of structure Strive for a tree structure that resembles a wide bushy shrub If you go too deep the markup begins to overwhelm the content and it becomes harder to edit a document too shallow and the information content is diluted Think of
483. s in a browser Example 7 5 The result tree snom eSDOUV lt ho income from 21 60 00 until 31 6 00 hn3 pol On 21 6 00 EtL5sSb 25987 22 D ti2 was deposited into your account by SL Bob s Bolirs lt 1 gt p gt lt h3 gt Expenditures from 21 6 00 until 31 6 00 ranked from highest to lowest lt h3 gt p gt On Sl 5 00 vou paid LL D55900 00 5b Rte to lt 1 Old Man Ferguson lt i gt for a 3 legged antique credenza that once belonged to Alfred Hrtchoock p epu On 29 65 00 You paid lt t gt b gt T7 lt D lt tE gt to 1X13mora Sports Equipment lt i gt for kendo equipment lt p gt Cp OH 3095 00 vou paid lt tt gt lt b gt 750 79 lt b gt lt x tt gt to lt i gt Barnes and Noble lt i gt for O Reilly Books lt p gt pod On 29 56 00 vou paid LL5 bbAT Z29 boelLtt to 4i Wild Oats Market i for groceries p lt p gt 5 On 24 6 00 you withdrew lt tt gt lt b gt S40 00 lt b gt lt tt gt from an ATM for pocket money lt p gt lt p gt 6 On 260 6 00 ou paid EL2 D29536 90 b LL to ihone Star Cafe lt i gt for lunch with Greg lt p gt lt h3 gt Balance lt h3 gt sp Your Dalanoe as of 3215 00 158 ErtLt 5 sb s ronrt color red gt S 128 38 lt font gt lt b gt lt tt gt lt p gt lt p gt lt font color red gt DANGER Deposit money quick lt font gt lt p gt lt body gt e BHtml Figure 7 1 Checkbook statistics in Netscap
484. s reason the public identifier must be accompanied by a system identifier here http www bobsbolts com catalog xml lf the XML processor for some reason can t handle the public identifier it falls back on the system identifier downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Most web browsers in use today can t deal with public identifiers so including a backup is a good idea The W3C has been working on an alternative to external parsed entities called XI nclude For details see http www w3 org TR xinclude 2 5 3 Unparsed Entities The last kind of entity discussedin this chapter is the unparsed entity This kind of entity holds content that should not be parsed because it contains something other than text or XML and would likely confuse the parser The only place from which unparsed entities can be referred to Is in an attribute value They are used to import graphics sound files and other noncharacter data The declaration for an unparsed entity looks similar to that of an external entity with some additiona information at the end For example CIDOCIYPER oc I lt ENTITY mypic SYSTEM photos erik gif NDATA GIF gt Sdooco lt para gt Here s a picture of me lt para gt egraphice Sre anyoic 7 gt lt Cdoc gt This declaration differs from an external entity declaration in that there is anNDATA keyword following the system path information This keyword tells the parser
485. s something is wrong and will report it Parsers are often used in conjunction with some other processing feeding a stream of tokens and repre data objects to be further manipulated At the moment however we re interested in parsing tools that in a document Instead of passing on digested XML to another program standalone parsers also called formedness checkers tell you when markup is good or bad and usually give you hints about what went look at an example In Example 1 10 I ve written a test document with a bunch of syntax errors guaran annoy any XML parser Example 1 10 A document that is not well formed XML 1 This document is not well formed and will invoke an error condition from an XML parser gt lt testdoc gt lt el gt overlapping lt e2 gt elements el here lt e2 gt lt e3 gt missing end tag lt e4 gt illegal character lt lt e4 gt lt testdoc gt Any parser worth its salt should complain noisily about the errors in this example You should expect to of error messages something like this downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 5 xwf ex4 noparse xml ex4 noparse xml 5 error Opening and ending tag mismatch e2 and el lt el gt overlapping lt e2 gt elements el here lt e2 gt ex4 noparse xml 5 error Opening and ending tag mismatch el and e2 lt el gt overlapping lt e2 gt elements el here lt e2 gt ex4 noparse xml 7 error xmlPar
486. s the bottom margin Finally if four values are specified they correspond to the top right bottom and left margins respectively Unspecified margins default to zero Thus the following rules are equivalent para margin left 10em margin right 10em margin top 5 Oo para margin 5 10em O In both cases the para element is defined with left and right margins of 10 ems a top margin of 5 of the containing element s height and no bottom margin Negative values are acceptable The result of a negative margin is to push the bounding box outside its container s box by the value given To create the effect of text spilling outside a colored region we use this stylesheet for an HTM file body 1 background color silver pot xxghb meroins L Margins often overlap For example paragraphs in a column touch at their top and bottom sides Instead of adding the margins to make a bigger space the smaller margin is discarded and the bigger one is used in its place This is calledcollapsing the margins So if a paragraph has a top margin of 24 points and a bottom margin of 10 points the actual distance between two paragraphs 24 points The rules of collapsing margins are actually a little more complex than this but a full explanation is beyond the scope of this chapter 5 4 4 2 Borders It s often appealing to surround an element with a rectangular outline to make it stand out The warning example used previously would
487. s the grandparent of this node an element of typecnapter Logically this is not so different from traditional XPath processing which usually starts from some absolute node and works its way into the depths of the document You just have to change your notion of where the path is starting from It might make more sense to rewrite the match pattern lik this abstract node child chapter child section child para where abstract node IS some node such that a location path extending from it matches a set of nodes that includes the node to process 7 5 2 Resolving Conflicts Among Rules It is possible for more than one rule to match a node In this case the XSLT processor must select exactly one rule from the mix and that rule should meet our expectations for best match Here are the rules of precedence among matching patterns 1 If the pattern contains multiple alternatives separated by vertical bars each alternative is treated with equal importance as though there were a separate rule for each 2 A pattern that contains specific hierarchical information has higher priority than a pattern that contains general information For example the pattern chapter section para Is more specific than para so it takes precedence 3 A wildcard is more general than a specific element or attribute name and therefore has lower priority The pattern stuff takes priority over the wildcard pattern Note that this is not true when hierarchical info
488. seStartTag invalid element name lt e4 gt illegal character lt e4 gt ex4 noparse xml 8 error Opening and ending tag mismatch e3 and testdoc lt testdoc gt The tool helpfully points out all the places where it thinks the XML is broken and needs to be fixed alon message indicating what s wrong Ending tag mismatch for example means that the end tag in quest match the most recently found element start tag which is a violation Many parsing tools will also valide supply a DTD for them to check against Where can you get a tool like this The easiest way is to get an XML aware web browser and open up ar with it It will point out well formedness errors for you though often just one at a time and can also va against a DTD Figure 1 11 shows the result of trying to load a badly formed XML document in Mozilla Figure 1 11 Browser showing XML syntax error If you prefer a command line tool like do you can find one online James Clark s nsgmls at http www jclark com sp originally written for SGML has served me well for many years If you are a developer it is not hard to use XML parsers in your code Example 1 11is a Perl script that XML LibXML module to create a handy command line validation tool Example 1 11 A validating parser in Perl usr bin perl use XML LibXML import parser library my Sparser new XML LibXML create a parser object Sparser gt validation 1 turn on validation
489. sed on wedding invitations and diplomas Since this is not a standar font category on most systems you should use it rarely if ever fantasy This collects all the oddball fonts like Comic Strip Ransom Note and Wild West Again most users are not likely to have access to this kind of font so use this category sparingly Examples of these typefaces are shown in Figure 5 12 Figure 5 12 Generic font families Let s say you want to select the typeface Palatino Zapf s Humanist 521 is generally held to be a high quality variant of Palatino Book Antiqua a clone from the Monotype foundry is not as carefully designed but it s fairly sturdy There are also cheap knock offs variously called Palisades or Palestine If neither Palatino nor any of its kin can be found Times New Roman is a handy substitute It doesn t have much in common with Palatino other than being another serif font but at least it s closer than Helvetica Times New Roman is sometimes found as Times Roman TmsRmn or Times Now you must decide how to order your list There is a trade off between including Palatino clones of doubtful quality or keeping the list short in favor of radically different but higher quality alternative typefaces Three approaches might be font family Palatino BT Humanist 521 Book Antiqua Palisades Times New Roman Times Roman Times serif font family Palatino Times New Roman serif font family BT Humanist 521 Palatino
490. ser fequiregunlPullParser orABI IAO0 null product String productName null otring price null while parser nextTag XmlPullParser END TAG parser reguirreidunrullPapPser orIARI LAG null null String name parser getName downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir String text parser nextText if name equals name productName text else if name equals price price text Patser require ANMLEULIPAPTSSIr BHD LAG hull Dane j parsger requireinunlPullParser B5ND TAG null Droducc Product newProduct new Product newProduct name productName newProduct price price return newProduct j Pull parsing is quickly becoming a favorite of developers Current implementations include Microsoft s NET XML libraries the streamable API for XML StAX XMLPULL and NekoPull Sun is standardizing a pull API for Java through JSR 172 Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 5 Standard APIs Nowadays all programs are written aslayered components where libraries provide functions or objects to take care of routine tasks like parsing and writing XML Anapplication programming interface API is a way of delegating routine work to a dedicated component An automobile s humar interface is a good example It is essentially the same from car to car with an ignition stee
491. ses the weight by one increment bolder Increases the weight by one increment Nine weight increments are available SO lighter and bolder can fine tune weight by 1 9 of the range Alternatively a numeric value can be used ranging from 100 to 900 in steps of 100 Not every font has nine weights so changing the number by 100 may not have a visible effect The value 400 corresponds to normal and bold is set to 700 Figure 5 14 shows some font styles and weights Figure 5 14 Font styles and weights 5 4 5 5 Color Color is an important feature for text especially with computer displays Text has two color properties color for the foreground and background color for the background There is a bevy of predefined colors you can call by name Alternately you can specify a color using i three number code where the numbers correspond to values forred green and blue RGB These numbers can be percentages integers from O to 255 or hexadecimal values from 000000 to ffffff Some examples are given in Table 5 1 Table 5 1 Color selections downloaded from lib ommolketab ir downloaded from fib ommolkcetab ir Preset Name Percentages Integers Hexadecimal aqua rob102 655 650 rgb D 150 150 00200 black um rgi Dt 9 000000 blue rdgb t 1005 rgb 0 60 400 0050ff fuchsia rgb 100 0 65 rgb 25090 l50 00a0 gray rgb 65 65 65 rgb 160 150 160 a0a0a0 green rab 0 100 0
492. set is a point the returned value is the point itself For nodes the value would be the start or end point for the covering range of that node These functions fail however for nodes of type attribute and namespace 6 4 4 5 Returning points from documents If the xpointer is inside an XML document it can use the functionhere to represent its location This would be useful for say specifying the origin of a link If the xpointer occurs inside a text node within an element the return value is the element Otherwise the node that directly contains the xpointer is returned Because the xpointer can only be at one place at any time only one item is returned in the location set Another function is origin It is only meaningful when used in the context of links returning the location of the link s origin where the user or program initiated traversal This is necessary for complex link types defined in XLink where the link s information does not reside at eitherof the endpoints Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 7 Transformation with XSLT Transformation is one of the mostimportant and useful techniques for working with XML To transform XML is to change its structure its markup and perhaps its content into another form A transformed document may be subtly altered or profoundly changed The process is carefully shaped with a configuration document
493. set to determine whether any of them satisfies the comparison Table 6 7 Comparison operators Operator Returns expr expr True if both expressions string or numeric have the same value otherwise false True if the expressions do not have the same value string or numeric otherwise false 2 True if the value of the first numeric expression is less than the value of the expr lt expr second otherwise false expr gt True if the value of the first numeric expression is greater than the value of the exprl l second otherwise false expr expr expr lt True if the value of the first numeric expression is less than or equal to the value of expri l the second otherwise false expr gt True if the value of the first numeric expression is greater than or equal to the exprltl value of the second otherwise false 2 f you use these operators inside an XML document such as an XSLT stylesheet or a Schematron schema you must use character references amp 1t and amp gt instead of and gt Listed in Table 6 8 are functions that return Boolean values Table 6 8 Boolean functions Function nction o Reems rns expr and spe True if both Boolean expressions are true otherwise false expr or expr True if at least one Boolean expression is true otherwise false downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Function Returns true sa pe false Fa
494. short tangential flow sidebars notes tips warnings footnotes and so on The main flow is typically formatted as a column other flows are often in boxes interrupting the main flow or moved to the side or the very end with son kind of link e g a footnote symbol Markup for flows are varied Some XML applications like XHTML do not support more than one flow Oth like DocBook have rich support for flows encapsulating them as elements inside the main flow The be representations allow flows to be moved around floated within the confines of the formatted page The main flow is broken up into sections which are hierarchical divisions that organize the document by topics usually with titles or heads For example a book is divided into chapters which are subdivided ir sections and subsections and subsubsections It is often convenient to treat these divisions as separate entities which can be stored in their own files and imported using the external entity mechanism This is useful if different people are working on sections in parallel such as with articles of a journal Sections are coded in two common ways In the first and less flexible scheme the section head is tagc downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir but no element is used to denote the boundary of the section like this lt bighead gt A major section lt bighead gt hesdA cute little se ction lt head gt lt paragraph g
495. side the formatter a complex operation in multiple phases takes place illustrated inFigure 8 1 We start with a result tree recall from Chapter 7 that a result tree is the product of an XSLT transformation in the XSL FO namespace In phase one of formatting the formatter translates this document into an object representation in memory in a process calledobjectification This structure a formatting object tree is structurally similar to the result tree but with some details changed For example all the character data will be replaced with o character node objects By making the tree more verbose like this later processing will run more efficiently Figure 8 1 The XSL FO formatting process downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Source document Forma thing Objectificatian OGc FOI FO tree Refined FO tree After objectification comes phase two refinement The formatter begins to calculate the actual geometry of areas in the presentation replacing relative values and constraints with concrete numbers For example a table cell whose width is specified as a percentage now will show that width as a number of pixels The percentage value for a relative width in a table will be replaced with a calculated number of pixels The product of this phase is arefined formatting object tree Next comes the formatting phase in which formatting object properties are translated into a virtual picture of
496. so known as ISO 646 It contains just 128 characters listed inFigure 9 1 Figure 9 1 The US ASCII character set downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir fa id a e em ere A at 13 OF l4 OF 2T 16 t2 17 2X MAR SYN ETB i T i T 50 80 52 R 5n 59 HU 5A LI 6l i s li i The first 32 codes are for control characters invoking some action from the device such ascR carriage return originally it used to make the print head on a teletype return to its leftmost position and BEL bell used to make a ding noise in the terminal Today many of the meanings behind these codes are somewhat ambiguous since the devices have changed The rest of the characters produce some kind of visible shape called aglyph These include uppercase and lowercase versions of the latin alphabet plus an assortment of punctuation digits and other typographical conveniences If you think of US ASCII as a function its domain is the set of integers from O to 127 Plug in the hexadecimal numbers 48 65 6C 6C 6F and 21 and you will get the string Hello back You migh think that this is how all electronic documents are represented In truth however it is usually more complex than that The character encoding for a document is the scheme by which characters are derived from the downloaded from lib ommolketab ir downloaded from fib ommol
497. space line height 24pt space after optimum 15pt background color 2 blue color white text align 2 center padding top 0pt gt lt xsl text gt TELEGRAM lt xsl text gt lt io block lt xsl apply templates gt lt xsl template gt lt xsl template match to gt fo block font family sans serif font size l4pt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir exelrtextoTO S7xSsltLtexLt xsl apply templates ro 5bopk lt xsl template gt lt xsl template match from gt lt fo block font family sans serif font size 14pt gt lt xsl text gt From lt xsl text gt xsl apply templates lt fosolock gt lt xsl template gt lt xsl template match subject gt lt fo block font family sans serif font size l4pt lt xsl text gt Subj lt xsl text gt lt xsl apply templates gt EelTOIDIeSE lt xsl template gt lt xsl template match message gt lt fo block font family monospace font size l0pt text align justify gt xsl apply templates errosplegs lt xsl template gt lt xsl template match emphasis gt fo inline font style italic gt xsl apply templates fo inline lt xsl template gt lt xsl template match name gt lt fo inline color green gt xsl apply templates lt Tolanline gt lt xsl template gt lt xsl template match villain gt lt fo inline color red gt xsl apply templates
498. specified by XSL 1 0 so it will likely be different depending on the implementation Width properties may be inherited by setting the value tc inherit The last component is style A large set of named styles are available none No visible border The width is effectively zero This is the default value for the style property hidden Like none but behaves differently in border conflicts between adjacent blocks dotted The border appears as a string of dots dashed The border is broken at intervals Solr d downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir A contiguous single line with no breaks double Like solid but with two parallel lines groove A 3D effect that paints the border to appear recessed as a trench ridge The opposite of groove the border seems to be a raised wall inset Another 3D effect in which the whole area seems to be recessed like a valley OULSGL The opposite of inset the area seems to be raised over surrounding terrain like a plateau Style properties can be inherited from parents in the FO tree by setting them toinherit 8 4 3 4 Font properties Most of the font properties available in CSS are present in FOs XSL goes a little further in some respects by allowing you to be more precise in specifying fallback fonts The specification gets very detailed about how font positioning works but it is out of the scope of this book So let us move on t the specific proper
499. ssumed to begin at the root node Jx Matches all sibling elements and the context node if it is an v element To see how axis and node tests can be used toretrieve nodes let s now look at some examples Consider the sample document in Example 6 1 Example 6 1 A sample XML document lt quotelist gt quotation style wise id gl gt lt text gt Expect nothing be ready for everything lt text gt lt source gt Samurai chant lt source gt lt quolation quotation style political id q2 gt lt text gt If one morning I walked on top of the water across the Potomac River the headline that afternoon would read President Can t owzxn bpexr source Lyndon B Johnson lt source gt downloaded from lib ommolketab ir downloaded from lib ommolketab ir elumotacron quotation style silly id q3 gt lt human laugh lt text gt What if the hokey pokey IS what it s all about lt text gt lt quotation lt quotation style wise id q4 gt lt text gt If they give you ruled paper write the other way lt text gt lt source gt Juan Ramon Jiminez lt source gt lt Morar Lon lt the checkbook is mightier than the sword gt quotation style political id q5 gt lt text gt Banking establishments are more dangerous than standing armies text source Thomas Jefferson lt source gt lt quotation lt quotelist gt Table 6 4 shows some location paths and what they would r
500. st so the DocB framers felt it easier to borrow it than to reinvent the wheel A note Is a new flow similar to a sidebar A formatter may or may not move it from this location v no damage to the narrative but it should stay relatively close to its origin This is how to code a footnote another new flow Footnotes are usually placed at the bottom of th page but that notion is not clear when talking about web pages This element contains significant extra whitespace that needs to be preserved The DTD has specif this for us so we don t need to insert an xml space attribute There are a lot of tools available for working with DocBook For more information see http docbook or Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 3 3 Complex Data XML really shines when data is complex It turns the most abstract concepts into concrete databases ready for processing by software Multimedia formats like Scalable Vector Graphics SVG and Synchronized Multimedia Integration Language SMIL map pictures and movies into XML markup Complex ideas in the scientific realm are just as readily coded as XML as proven by MathML equations the Chemical Markup Language chemical formulae and the Molecular Dynamics Language molecule interactions 3 3 1 Elements as Objects The reason XML is so good at modelling complex data is that the same building blocks for narrative documents el
501. starts 15mm provisional label separation b5mm xsl apply templates ro rlist blogck lt xsl template gt lt xsl template match itemizedlist listitem gt rto list item fo list item label start indent b5bmm end indent label end gt Crorbplogkb elteygztfotblooks fo list item label fo list item body start indent 2 body start STrOSDLOQES xsl apply templates amp T055blppls fo list item body fo list item lt xsl template gt Following is a term definition list wanted the terms and definitions to appear on separate lines so decided to forgo the traditional list FOs lt xsl template match variablelist gt xsl apply templates downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt xsl template gt lt xsl template match varlistentry gt xsl apply templates lt xsl template gt lt xsl template match varlistentry term gt SIDIDIDOKR font weight 2 bold Space after 2mm keep with next within page 2 xsl apply templates e foesblopke lt xsl template gt lt xsl template match varlistentry listitem gt SIO DIOCK margin left 10mm space after 2mm xsl apply templates JLo tO Lock lt xsl template gt 8 6 6 Footnotes Footnotes are the strangest objects yet Even though in the DocBook source the content is embeddec in the narrative in the presentation it pops out of the flow and drops to the
502. store anystate information contextual clues that would help in decisions for how to parse so the application has to store this information itself Pull parsing is just the opposite The program takes control and tells the parser when to fetch the next item Instead of reacting to events it proactively seeks out events This allows the developer more freedom in designing data handlers and greater ability to catch invalid markup Consider the following example XML ocoatelog eproducrt zde ronoco 720 lt name gt Widget lt name gt lt price gt 19 99 lt price gt epr product id acme 229 lt name gt Gizmo lt name gt lt price gt 28 98 lt price gt SIDPOUUOD catalog It is easy to write a SAX program to read this XML and build a data structure The following code assembles an array of products composed of instances of this class Clase Produce 1 String name String price Here is the code to do it StringBuffer cdata new StringBuffer Product catalog new Product 10 String name Float price public void startDocument 1 index 0 public void startElement String uri String local String raw Attributes attrs throws SAXException cdata clear downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir public word characters Char chll int start ont length throws SAXException cadata dppend ch Start length J public void endElement String uri St
503. stroyed lt para gt lt refsectl gt lt Versecc il gt lt tit lessee alsoc titles lt simplelist gt lt member gt lt link href head xml gt head 1 lt link gt lt member gt lt member gt lt link href more xml gt more 1 lt link gt lt member gt lt member gt lt link href pr xml gt pr 1 lt link gt lt member gt ememberoe lint hrers rall xml rtail l s linkse membert e memberoecline hrere vis unl wistl linkoe member e simplelist lt para gt Rob Pike lt citetitle gt UNIX Style or cat v Considered Harmful citetitle USENIX Summer Conference Proceedings 1983 para downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir refsectl refsectl title History title lt para gt A lt command gt cat lt command gt utility appeared in Version 6 AT amp T UNIX lt para gt refsectl lt refentry gt The first thing you ll notice is that DocBook is a lot more verbose than HTML Thevariablelist cousin t HTML s definition list is a chore to type out But there certainly is no doubt about what an element stanc which is necessary in a markup language with so many elements If every tag name was an abbreviatioi two letters there d be no hope of ever memorizing a fraction of the langauge The structure of the document element refentry Is highly specialized Whereas HTML adopts a strategy where every document has the same overall structure DocBook is very closely bound t
504. synopses or code listings But HTML provides very few types of block elements and am obligated to us whatever is available Using HTML for this example has good and bad points The good side is that HTML is easy to use so w able to mark up the manual page in only a few minutes With only a few element types to remember have to look in a book to know which one to use and how it will look when formatted The downside is tl now have a document fit for only one purpose displaying in a web browser A printout is likely to look primitive And for other purposes like searching and indexing the lack of granularity is likely to prevent downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir from doing anything truly useful Until need the extra functionality I m happy with HTML But if ever plan to use a document in more t one way l Il need to explore other options Something more specific to my brand of data will fit better a give me more options What will show you next is amarkup language specifically designed for the kind information shown in the last example 3 2 7 DocBook DocBook is a markup language designed specifically for technical documentation modelling everything f one page user manuals to thousand page tomes Like HTML it predates XML and was first an SGML application Also like HTML it has migrated to XML and works very well in that framework Unlike HTML DocBook is very large and comes w
505. syntax mistakes to recover It may make it harder to write XML since the user has to pay attention to details but this is a small price to pay for robust performance Separate markup from presentation For your document to have maximum flexibility for output format you should strive to keep the style information out of the document and stored externally Documents that rely on stylistic markup are difficult to repurpose or convert into new forms For example imagine a document that contains foreign phrases that are marked up to be italic and emphatic phrases marked up the same way like this lt example gt Goethe once said lt i gt Lieben ist wie Sauerkraut lt i gt I lt i gt really lt i gt agree with that statement lt example gt Now if you wanted to make all emphatic phrases bold but leave foreign phrases italic you d have to manually change all the lt i gt tags that represent emphatic text A better idea is to tag things based on their meaning like this lt example gt Goethe once said lt foreignphrase gt Lieben ist wie Sauerkraut lt foreignphrase gt I lt emphasis gt really lt emphasis gt agree with that statement lt example gt Instead of being incorporated in the tag the style information is defined in another place a document called a stylesheet Stylesheets map appearance settings to elements acting as look up tables for a formatting program They make things much easier for you You can tinker with the
506. t Sure you can get a little thrill looking at your bank statement and seeing the dividend from the 396 interest on your savings account but it isn t as exciting as buying a new plasma screen television So it is with XML contains information like a safe holds money but the real fun comes from using that information Whether you re publishing an XHTML document to the Web or generating an image from SVG the results are much more gratifying than staring at markup XML s extended family provides many ways to squeeze usefulness out of XML documents They are extensions and applications of XML that build bridges to other formats or make it easier to work with data All the names and acronyms may be a little overwhelming at first but it s worth getting to know this growing family Let s look at these categories in more detail Core syntax These are the minimal standards required to understand XML They include the core recommendation and its extension Namespaces in XML The latter piece allows you to classify markup in different groups One use of this is to combine markup from different XML applications in the same document The core syntax of XML will be covered thoroughly in Chapter 2 Human documents This category has markup languages for documents you ll actually read as opposed to raw data XHTML the XML friendly upgrade to the Hypertext Markup Language is used to encode web pages DocBook is for technical manuals which are heavy in t
507. t secondary gt lt indexterm gt lt para gt The wood sprite likes to hang around rotting piles of wood and is easily dazzled by bright lights lt para gt lt section gt lt title gt lt indexterm gt lt primary gt little people lt primary gt lt indexterm gt Origins lt title gt lt para gt No one really knows where they came from lt para gt lt indexterm gt lt primary gt magical folk lt primary gt lt indexterm gt lt section gt lt chapter gt have placed indexterms In various places both inside and outsidetitles to see which ones are affected Here is the result after running the script on it cm Version 1 0 gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir chapter lt title gt Habits of the Wood Sprite lt title gt lt indexterm gt lt primary gt woodland faeries lt primary gt lt indexterm gt lt indexterm gt lt primary gt wee creatures lt primary gt lt indexterm gt lt indexterm gt lt primary gt sprites lt primary gt lt secondary gt woodland lt secondary gt lt indexterm gt lt para gt The wood sprite likes to hang around rotting piles of wood and is easily dazzled by bright lights lt para gt lt section gt lt title gt Origins lt title gt lt indexterm gt lt primary gt little people lt primary gt lt indexterm gt lt para gt No one really knows where they came from lt para gt lt indexterm gt lt primary gt magical folk lt primary gt
508. t xsl when gt xsl when test Self appendix gt lt xsl text gt APPENDIX lt xsl text gt xsl call template name chapnum gt lt xsl when gt lt xsl choose gt a7 LOCO kh CTOSDIODE border rtope solid Ipr black padding before 2 2mm font family myriad verdana sans serif tfont weight bold font size 18pt text align right xsl apply templates select title gt lt Io Dlock lt Tototatic content gt fo static content flow name region first recto after gt SIOSDIOCK border top solid lpt black padding before 2mm font family myriad verdana sans serif font weight bold font size 8pt downloaded from fib ommolkcetftab ir downloaded from lib eommolketab ir text align right lt fo page number gt lt T oO DLock gt Torsratic conbtemc i1 REST OF CHAPTER ON ODD PAGE gt fo static content flow name region other verso after To Loo border top solid lpt black padding before 2mm font family myriad verdana sans serif font weight bold font size spr text align 2 left gt lt fo page number gt lt fo inline fFont size 12pt gt explepexto lt xelttexc lt fo inline gt lt xsl choose gt xsl when test self chapter xsl text Chapter xsl text xsl call template name chapnum gt lt xsl when gt xsl when test 2 self appendix lt xsl text gt Appendix lt xsl text gt xsl call template name
509. t Some text paragraph lt head gt Another cute little section lt head gt lt paragraph gt Some text lt paragraph gt In the other better scheme the section has definite boundaries created by a container element section lt head gt A major section lt head gt lt subsection gt lt head gt A cute little section lt head gt lt paragraph gt Some text lt paragraph gt lt subsection gt lt subsection gt lt head gt Another cute little section lt head gt lt paragraph gt Some text lt paragraph gt lt subsection gt lt section gt The first is called a flat structure It is less desirable because it relies on presentational details to divine parts of the document begin and end In this case a bigger head means a larger section is beginning ai small head indicates a subsection is starting It s harder to write software to recognize the details of flat structures than of hierarchical structures XHTML for example is typically flat In contrast the markup language DocBook is hierarchical We ll see examples ofthese shortly 3 2 2 Blocks and Inlines A block is a type of element that contains a segment of a flow and is typically formatted as a rectangulai region separated from other blocks by space above and below Unlike sections blocks hold mixed conte both character data and elements Examples of blocks are paragraphs section heads and list items Elements inside blocks are called inline elements
510. t but have it format as a block A figure I a structure that acts as a block set off from the text with a caption This is easy to achieve by encapsulating the excernal graphic In a block The following XSLT template formats a figure element this way lt xsl template match figure gt lt fo block margin 10mm gt ro block margin bottom smm gt fo external graphic src fileref gt lt 7 Foz clock SLIOIDIOQE xsl apply templates match caption gt lt Lo block fi ez block lt xsl template gt 8 4 4 4 Generated content Another class of inline objects stand in for text that has to be generated during the formatting process For example a cross reference that cites a page number should not be hardcoded but left to the formatter to fill in The formatting object page number will be replaced at formatting time with the number of the page it appears on This is used often in headers or footers where you want to keep a running page number as in the following example fo static content flow name header left it oa oN ie ay 4 font size 8pt text align left fo page number fTobLOGRksS e fosstatric oontent A similar need is the cross reference containing the page number of the object it points to Suppose in the course of writing a book you want to make a reference to a table in another chapter giving the page number on which it appears page number citation is the FO you want to use The XSLT
511. t don t know how to work with them Third it isn t really part of the document anyway but rather a recommendedway to work with the information 5 1 3 Limitations Not surprisingly there are limits to what you can do with stylesheets Languages for stylesheets are optimized for different purposes You need to be aware of how a stylesheet language works to use it most effectively CSS for example is designed to be compact and efficient Documents have to be rendered quickly because people don t want to wait a long time for something to read The stylesheet processor is on the client end and doesn t have a lot of computing power at its disposal So the algorithm for applying styles needs to be very simple Each rule that matches an element can only apply a set of styles There is no other processing allowed no looking backward or forward in the document for downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir extra information You have only one pass through the document to get it right Sometimes information is stored in an order other than the way you want it to be rendered If that i the case then you need something more powerful than CSS XSLT works on a tree representation of the document It provides the luxury of looking ahead or behind to pull together all the data you nee to generate output This freedom comes at the price of increased computational requirements Although some browsers support client sid
512. t in external files and declared as external entities See also DTD Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB N name Any object in XML has a type specifier called a name For example an element that describes the title of a book might be given the namebooktitle The representation of the element must include the name in both its start and end tags like this lt booktitle gt Wart Removal lt booktitle gt Names in XML must obey rules about character composition For example element names must start with either an underscore or a letter See also attribute element markup namespace Any of a group of specified elements and attributes that can be used in a document by prefixing a namespace identifier to an element name e g namespace element Namespaces must be declared using the xmlns declaration The following syntax is used for a namespace declaration lt xmlns name uri gt The name of the namespace is given by name and the location of the namespace maintainer or version is given by uri though parsers usually don t do anything with this information Namespaces allow you to mix different sets of element definitions in a single document for example using mathematical equations in an HTML document See alsoelement qualified element name namespace prefix The identifier preceding an element s name that indicates the namespace it belongs to e g
513. t into one ofthree categories of formatting block inline and none These designations listed here govern how the content is packaged in the formatted document block A block is a rectangular region of text isolated from the content preceding and following it by spacing It begins on a new line often after some whitespace and it has boundaries called margins that keep the text in the rectangular shape The textwraps at the margin meaning it stops and then restarts on the next line Blocks can contain other smaller blocks as well as inlines Examples of blocks in traditional documents are paragraphs titles and sections inline An inline is content that doesn t interrupt the flow of text in a block It wraps at the margin of the block it resides in like ordinary character data It can set properties that don t affect the flow such as font family and color but cannot have properties related to blocks such as text alignment and text indentation Examples of inlines are emphasis keywords and hypertext links downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir none Any element defined as display none will be skipped by the CSS processor It s a convenient way to turn off large portions of a document for faster processing It also happens to be the only display setting that is inherited since all the children of the element are ignored too Every element is assigned adisplay property that tells the C
514. t objects or auxiliary objects help produce areas by contributing parameters A block object creates a region of content to be inserted into a flow so it qualifies as a flow object In contrast the initial page number FO resets the count of page numbering Since it only contributes some information to aid in processing rather than create regions on its own it is a layou object An FO document structure is a tree like any other XML document Every element in it is a formatting object so we call it an FO tree The root of this tree is aroot element Its children include layout master set This element contains page layout descriptions declarations Optional this element contains global settings that will affect overall formatting page sequence One or more of these elements contain flow objects that hold the content of the document In the coming sections will break down this structure further starting with page layout From there we will move to flows blocks and finally inlines 8 4 1 Page Layout Contained in the layout master set object are specifications for pagination and layout There are two types page masters define properties of a page type its geometry and how it is subdivided page sequence masters control how page types will appear in sequence When the formatter formats pages it will take the content inside the flow object children of the page sequence Objects and fit it into pages The shape of the formatt
515. t of default rules to makethe job of writing stylesheets easier If no rule from the stylesheet matches the default rules provide an emergency backup system Their general behavior i to carry over any text data in elements from the source tree to the result tree and to assume an implicit xsl apply templates element to allow recursive processing Attributes without matching templates are not processed The following list sums up the default rules for each type of node Root Processing starts at the root To force processing of the entire tree the default behavior is to apply templates to all the children The rule looks like this lt xsl template match gt xsl apply templates lt xsl template gt Element We want the processor to touch every element in the tree so it does not miss any branches for which rules are defined The rule is similar to that for the root node lt xsl template match gt xsl apply templates lt xsl template gt Attribute Attributes without matching templates are simply ignored lt xsl template match gt Text It is inconvenient to include thexs1 value of element in every template to output text Since we almost always want the text data to be output it is done by default lt xsl template match text gt lt xsl value of select gt lt xsl template gt Processing instruction By default these nodes are left out The rule is this lt xsl template match processing inst
516. t removeChild nodeRef my SancestorNodeRef SparentNodeRef parentNode SancestorNodeRef gt insertAfter nodeRef SparentNodeRef H dt At the top of the procedure are lines that select which element to process Since this procedure is called for every element we have to weed out the ones we don t want to touch The first test determines whether the element is an lt indexterm gt and if it is not returns immediately The next two lines examine the parent of this element aborting unless it is of typetitle If processing gets past these two tests we know this must be an indexterm inside a title The processing that follows removes the offendingindexterm element from its parent s list of children and inserts it into the list of its parent s parent s children just after the parent So the indexterm goes from being a child of title to being its sibling positioned immediately after it This puts the element where it will do no harm to the formatter and will still be seen by an index generator later Wasn t that simple Example 10 5 shows the complete program Example 10 5 A DOM program for moving indexterms out of titles usr bin perl use XML LibXML my Sparser new XML LibXML my nodeTypes element gt attribute gt 2 text gt 3 cdatasection gt 4 entityref gt 5 entitynode gt 6 PECCINSt ruc gt 7 comment gt 8 document gt 9 Pe foreach my fileName ARGV my SdocRef
517. t they should be retired in favor of the one true W3C XML Schema 4 1 2 3 RELAX NG An independent effort by a creative few coalesced into another schema language called RELAX NG pronounced relaxing It is the merging of Regular Language Description for XML RELAX andTree Regular Expressions for XML TREX Like W3C Schema it Supports namespaces and datatypes It also includes some unique innovations such as interchangeability of elements and attributes in content descriptions and more flexible content models RELAX a product of the Japanese Standard Association s INSTAC XML Working Group led by Murata Makoto was designed to be an easy alternative to XML Schema Tired of complex specifications the home page asks You can relax Unlike W3C Schema with its broad scope and high learning curve RELAX is simple to implement and use You can think of RELAX as DTDs formatted in XML plus datatypes inherited from W3C Schema s datatype set As a result it is nearly painless to migrate from DTDs to RELAX and if you want to do so later fairly easy to migrate from RELAX to W3C Schemas It supported two levels of conformance Classic is just like DTD validation plus datatype checking Fully relaxed added more features The theoretical basis of RELAX is Hedge Automata tree processing While you don t need to know anything about Hedge Automata to use RELAX or RELAX NG these mathematical foundations make i easier to write efficient code impl
518. t to HTML than to PDF Database integration is another feature to consider In an environment where data comes from many sc as multiple authors in collaboration or records from databases an editor that can communicate with a c be a big deal Databases can be used as a repository for documents giving the ability to log changes rr ownership and store older versions Databases are also used to store raw data such as personnel recor inventory and you may need to import that information into a document such as a catalog Editors like XML Spy support database input and collaboration They can update documents in many places when de have changed and they can branch document source text into multiple simultaneous versions There ar exciting possibilities downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Which editor you use will depend a lot on your budget You can spend nothing and get a very decent edi emacs It doesn t have much of a graphical interface and there is a learning curve but it s worked quite Or for just a couple hundred dollars you can get a nice editor with a GUI and parsing ability like Morph You probably wouldn t need to spend more unless you re in a corporate environment where the needs fc quality formatting and collaboration justify the cost and maintenance requirements Then you might buy of high end editing systems like Epic or FrameMaker With XML there is no shortage of choices 1 4 2 Viewin
519. t will override the global setting In Figure 5 9 a para inherits some properties from a section which in turn inherits from an article The properties font family and color are defined in the property set for article and inherited by both section and para The property font size Is not inherited by section because section s explicit setting overrides it para does inherit this property from section Figure 5 9 Element inheriting properties Inheritance is forbidden for some properties where it wouldn t make sense to pass that trait on For example the background image property which causes an image to be loaded and displayed in the background is not inherited If every element did inherit this property the result would be a complete mess with every paragraph and inline element trying to display its own copy of the image in its rectangular area It looks much better if only one elementhas this property and its children don t Display type and margins are other examples downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 5 4 2 Units of Measurement Many properties involve some kind of measurement the width of a rule a font size or a distance to indent These lengths can be expressed in several different kinds of units Absolute measurements use units that have a predefined size such as inches points or picas Relative measurements use percentages and fractions of some variable distance such as the height of
520. ta It evolved from discussions on the XML DEV mailing list and shepherded by David Megginson H was quickly shaped into a useful specification 1 David Megginson maintains a web page about SAX at http www saxproject org The first incarnation called SAX Level 1 or just SAX1 supports elements attributes and processin instructions It doesn t handle some other things like namespaces or CDATA sections so the second iteration SAX2 was devised adding support for just about any event you can imagine in generic XML Since there s no good reason not to use SAX2 you can assume that SAX2 is what we are talking about when we say SAX SAX was originally developed in Java in a package calledorg xml sax As a consequence most of the literature about SAX is Java centric and assumes that is the environment you will be working in Furthermore there is no formal specification for SAX in any programming language but Java Analog in other languages exist such as XML SAX in Perl but they are not bound by the official SAX description Really they are just whatever their developer community thinks they should be David Megginson has made SAX public domain and has allowed anyone to use the name An unfortunate consequence is that many implementations are really just flavors of SAX and do not match in every detail This is especially true for SAX in other programming languages where the notion of strict compliance would not even make sense This is
521. tations as it may not be a good fit with your problem How do I get started Without any hesitation hope I ll describe the tools you need to get going with XML and test the examples in this book From authoring validating checking well formedness transforming formatting and writing programs you ll have a lot to play with So now let us dive into the big questions By the end of this chapter you should know enough to decide where to go from here Future chapters will describe topics in more detail such as core markup quality control style and presentation programming interfaces and internationalization Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 1 1 What Is XML XML is a lot like the ubiquitous plastic containers of Tupperware There is really no better way to keep your food fresh than with those colorful airtight little boxes They come in different sizes and shapes so you can choose the one that fits best They lock tight so you know nothing is leaking out and germs can t get in You can tell items apart based on the container s color or even scribble on it with magic marker They re stackable and can be nested in larger containers in case you want to take them with you on a picnic Now if you think of information as a precious commodity like food then you can see the need for a containment system like Tupperware 1 1 1 An Information Container XML c
522. tedious to use the predefined entities amp 1t amp gt and amp amp They require typing and are generally hard to read in the markup There s another way to include lots of forbidden characters however the CDATA section CDATA is an acronym for character data which just means not markup Essentially you re telling the parser that this section of the document contains no markup and should be treated as regular text The only thing that cannot go inside a CDATA section is the ending delimiter gt A CDATA section begins with the nine character delimiter lt CDATA 1 and it ends with the delimiter 3 The content of the section 2 may contain markup characters lt gt and amp but they are ignored by the XML processor seeFigure 2 22 Figure 2 22 CDATA section syntax Here s an example of a CDATA section in action lt para gt Then you can say CDATA if amp x lt amp y gt and be done with it para This Is effectively the same as lt para gt Then you can say if amp amp x amp lt amp amp y and be done with it para CDATA sections are convenient for large swaths of text that contains a lot of forbidden characters However the very thing that makes them useful can also be a problem You will not be able to use any elements or attributes inside the marked region If that s a problem for you then you would probably be better off using character entity references or entities
523. templates d desi lt xsl template gt It extracts the value of the attribute label and outputs it literally as the content of aat element Besides nodes value of can be used to resolve variables as you will see in the next section 7 6 3 Variables A convenience provided in XSLT is the ability to create placeholders for text calledvariables Contrary to what the name suggests it is not actually a variable that can be modified over the course of processing It s really a constant that is set once and read multiple times A variable must be defined before it can be used For that you can use thevariable element Here are some examples of declaring variables amp l A MUM rio constanL gt lt xsl variable name year select 2001 gt lt A string consisting of two blank lines useful for making output XML easier to read lt xsl variable name double blank line lt xsl text gt lt xsl text gt lt xsl variable gt lt A concatenation of two elements string values lt xsl variable name author name gt lt xsl value of select book bookinfo authorgroup author firstname gt lt xsl text gt lt xsl text gt lt xsl value of select book bookinfo authorgroup author surname gt lt xsl variable gt The first example sets the variable to a string value The last two examples set the variables to resul tree fragments These are XML node trees that will be copied into the result tree do
524. tent in the document other than whether an element can contain character data Although attributes can be declared to be of different types e g ID IDREF enumerated there is nc way to constrain the type of data in an element Returning to the example in Section 4 2 3 we can see how this limitation can be a serious problem Suppose that a census taker submitted the document in Example 4 5 Example 4 5 A bad CensusML document census record taker 9170 gt lt date gt lt month gt lt month gt lt day gt 110 lt day gt lt year gt 03 lt year gt lt date gt lt address gt city Munchki nland lt city lt SL reer gt lt st reer gt lt count y gt count y gt lt country gt Here silly lt country gt lt postalcode gt lt postalcode gt lt address gt person employed fulltime pid gt name lt last gt Burgle lt last gt lt LiLPStosrad lt 1i1Sst gt lt name gt lt age gt 2131234 lt age gt lt gender gt yes lt gender gt lt person gt census record There are a lot of things wrong with this document The date is in the wrong format Several important fields were left empty The stated age is an impossibly large number The gender which ought to be male or female contains something else The personal identification number has a bad value And yet to our infinite dismay the DTD would pick up none of these problems It isn t hard to write a program that would check the data types but th
525. ternate access by index is also provided for enumerations but no order is implied downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 10 9 1 6 1 Properties Here are the properties for the NamedNodeMap class length Returns an integer indicating the number of nodes in the list 10 9 1 6 2 Methods Here are the properties for the NamedNodeMap class getNameditem setNameditem Retrieves or adds a node using the node s nodeName property as the key removeNamedItem Takes a node with the specified name out of the set and returns it item Given an integer value n returns a reference to the nth node in the set Note that this method does not imply any order and is provided only for unique enumeration getNamedItemNS DOM 2 only Retrieves a node based on a namespace qualified name a namespace prefix and a local name removeNamedItemNS DOM 2 only Takes an item out of the list and returns it based on its namespace qualified name setNamedItemNS DOM2 only Adds a node to the list using its namespace qualified name 10 9 1 7 CharacterData This class extends Node to facilitate access to certain types of nodes that contain character data suct aS Text CDATASection Comment and ProcessingInstruction Specific classes like Text inherit from this class 10 9 1 7 1 Properties Here are the properties for the CharacterData Class data The character data itself length downloaded from lib om
526. ters downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir objects overview of page layout printing processing TEI XML XSLT Extensible Stylesheet Language Transformation 2nd 3rd elements executing formatting history of lang function modularity overview of programming templates 2nd default rules matching nodes naming precedence redirecting variables Xalan stylesheet processor web site XT XSLT transformation program web site Team LiB downloaded from fib ommolkcetftab ir
527. tes for a set of element or attribute types We ve already seen one choice which matches an enumerated set of elements and attributes Even more permissive is the name class anyName which allows any element or attribute type to have the described content model For example this pattern matches any well formed document lt grammar xmlns http relaxng org ns structure 1 0 SSLeIrL ref name all elements X i um ham define name all elements element lt anyName gt lt use in place of the name attribute lt zeroOrMore gt choice ref name anyElement text lt attribute gt lt anyName gt lt attribute gt lt choice gt lt zeroOrMore gt lt element gt define lt grammar gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The anyName appears inside the element instead of a name attribute The zeroOrMore IS required here because each name class element matches exactly one object The nsName class matches any element or attribute in a namespace specified by anns attribute For example lt element xmlns http relaxng org ns structure 1 0 nsName ns http fakesite org lt empty gt lt element gt This will set any element in the namespacehttp fakesite org to be an empty element If you leave out the ns attribute nsName will inherit the namespace from the nearest ancestor that defines one So this will also work lt
528. th a document Yes Yes No NO 7 Added later in the RELAX NG DTD Compatibility specification DTDs have been around the longest so as you would expect they have the widest support in literature and software They also have the advantage of being the only way to declare entities at the moment The syntax for DTDs is very easy to learn although its readability often leaves much to be desired Try reading the DocBook XML DTD sometime and you ll see what mean After a fashion it is modular but find the parameter entities are often a nuisance especially when you want to override imported declarations W3C XML Schema has the advantage of being blessed by the W3C so you can be sure it will win many converts Software support is growing quickly think it s pretty decent but it has a clunkiness to it that can make schema design a chore The datatypes will become a de facto standard as they are already borrowed upon by the likes of RELAX NG In general this is a good step forward but be aware that there will always be contenders for the throne RELAX NG has won my admiration for its elegance and simplicity Writing schemas is easy and reading them even easier It is easily translated into other schema languages such as W3C Schema and DTDs using Trang making it an ideal starting point for schema development Niceties like interleave and nested grammars are not to be overlooked It would be nice to see more built in type downloaded
529. that the entity s content is in a special format or notation other than the usual parsed mixed content TheNDATA keyword is followed by a notation identifier that specifies the data format In this case the entity is a graphic file encoded in the GIF format so the word GIF is appropriate Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 2 6 Miscellaneous Markup Rounding out the list of markup objects are comments processing instructions and CDATA sections They all have one thing in common they shield content from the parser in some fashion Comments keep text from ever getting to the parser CDATA sections turn off the tag resolution and processing instructions target specific processors 2 6 1 Comments Comments are notes in the document that are not interpreted by the XML processor If you re working with other people on the same files these messages can be invaluable They can be used to identify the purpose of files and sections to help navigate a cluttered document or simply to communicate with each other Figure 2 21 shows the form of a comment It starts with the delimiter lt 1 and ends with the delimiter 3 Between these delimiters goes the comment text 2 which can be just about any kind of text you want including spaces newlines and markup The only string not allowed inside a comment is two or more dashes in succession since the parser would
530. the current font You can measure an absolute length with a ruler because the units never change A millimeter is the Same no matter what font you re using or which language you re speaking Absolute units used in CSS include millimeters mm centimeters cm and inches in as well as units specific to the world of print such as points pt and picas pc Relative units are nonfixed scaling values that depend on some other measurement For example at em Is defined as the size of the current font If that font happens to be 12 points then an em is 12 points If the font size changes to 18 points so does the em Another relative unit is an ex defined t be the x height of a font the height of a lowercase x This is a fraction of the em usually around a half but it changes depending on the font Different fonts can have different x heights even if their em sizes are the same Relative measurements can also be expressed as percentages This type of measurement relies on another element s value of the same property For example b font size 200 means that the b element has a font size that is twice its parent s In general relative measurements are better than absolute Relative units don t have to be rewritten when you adjust the default properties It s much easier to write a stylesheet for multiple scenarios when you define the base size in only one place and everything else isrelative 5 4 3 Display Types Most elements fi
531. the data is more consistent 1 1 2 2 Validity Some programs are not so general purpose however They may perform complex operations on highly specific data In this case you may need to concretize your markup language so that a user doesn t slip in an unexpected element type and confuse the program What you need is a formal document model A document model is the blueprint for aninstance of a markup language It gives you an even stricter test than well formedness so you can say that Document X is not just well formed XML but it s also an instance of the Mathematics Markup Language for example When a document instance matches a document model we say that it isvalid You may hear it phrased as this is valid XHTML or valid SVG The markup languages e g XHTML and SVG are applications of XML Today there are hundreds of XML applications for encoding everything from plays to chemical formulae If you re in the market for a markup language chances are you ll find one that meets your needs If not you can always make your own That s the power of XML downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir There are several ways to define a markup language formally The two most common are document type definitions DTDs and schemas Each has its strong points and weak points 1 1 2 3 Document type definitions DTDs DTDs are built into the XML 1 0 specification They are usually separate documents that you
532. the declaration doesn t actually specify that thecensus record must be used as the document element In fact a DTD can t single out any element to be the root of a document You might view this as a bad thing since you can t stop someone from submitting an incomplete document containing only a person element and nothing else On the other hand you could see it as a feature where DTDs can contain more than one model for a document For example DocBook relies on this to support many different models for documents a book would use thebook element as its root while an article would use thearticle element In any case be aware of this loophole Now we should declare the attributes for this element There is only one taker identifying the census taker who authored this document Its type is CDATA character data We will make it required because it s important to know who is submitting the data just to make sure no mischievous people submit fraudulent records Here is the attribute list forcensus record lt ATTLIST census record taker CDATA REQUIRED gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Next declare the date element The order of element declarations doesn t really matter All the declarations are read into the parser s memory before any validation takes place so all that is necessary is that every element is accounted for But like things organized and in the approximate order so here s the ne
533. the public on the wek at http www w3 org TR REC xml As a recommendation it isn t strictly binding There is no downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir certification process but developers are motivated to comply as closely as possible to attract customers and community approval In one sense a loosely binding recommendation is useful in that standards enforcement takes time and resources that no one in the consortium wants to spend It also allows developers to create their own extensions or to make partially working implementations that do a pretty good job The downside however is that there s no guarantee anyone will do a really good job For example the Cascading Style Sheets standard has languished for years because browser manufacturers couldn t be bothered to fully implement it Nevertheless the standards process is generally a democratic and public focused process which is a Good Thing The W3C and the Standards Process The W3C has taken on the role of the unofficial smithy of the Web Founded in 1994 by a inumber of organizations and companies around the world with a vested interest in the Web their long term goal is to research and foster accessible and superior web technology with responsible application They help to banish the chaos of competing half baked technologies by issuing technical documents and recommendations to software vendors and end users alike Every recomm
534. their excellent advice and enthusiasm Thanks to the open source community for making software development as fun as it is useful And thanks to my friends and family for putting up with all this geeky stuff when really should have been out working on my tan Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 1 Introduction Anywhere there is information you ll find XML or at least hear it scratching at the door XML has grown into a huge topic inspiring many technologies and branching into new areas So priority number one is to get a broad view and ask the big questions so that you can find your way through the dense jungle of standards and concepts A few questions come to mind What is XML We will attack this from different angles It s more than the next generation of HTML It s a general purpose information storage system It s a markup language toolkit It s an open standard It s a collection of standards It s a lot of things as you ll see Where did XML come from It s good to have a historical perspective You ll see how XML evolved out of earlier efforts like SGML HTML and the earliest presentational markup What can do with XML A practical question again with several answers you can store and retrieve data ensure document integrity format documents and support many cultural localizations And what can t do with XML You need to know about the limi
535. them as references It also handles whitespace differently preserving all newlines and indentation 7 6 2 Outputting Node Values XPath introduced the notion of anode s string value All the text in an element is assembled into a string and that is what you get So in this element sentence subject The quick brown lt noun gt fox lt noun gt lt subject gt action jumped over lt action gt lt object gt the lazy lt noun gt dog lt noun gt lt object gt lt sentence gt The text value is The quick brown fox jumped over the lazy dog In the default rules all text nodes that are the children of elements are output literally If you have no explicit template for text nodes then any apply templates directive that matches a text node will resort to the default rule and the text will be output normally downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir However there are cases when you can t rely on the default rules You may want to output the value of an attribute for example Or else you might want to get a string without any markup tags in it When this is the case you should usevalue of This element requires an attribute select which takes an XPath expression as its value value of simply outputs the string value of that expression Recall from Example 7 2 this template lt xsl template match part label gt eut lt xsl value of select label gt lt dt gt eod xsl apply
536. themselves Real Power Switch An invisible fingerprint scanning E um Gn eke oe zo o shom o uhk sumo m zm Danodh mam sido dam Finally a view of a whole page appears inFigure 8 14 Of note here are the chapter opener header e bulleted list and a comment in italic Figure 8 14 A screenshot of the whole page Overall my experience with XSL FO was very positive found it easy to learn and 95 of the things wanted to do were straightforward A few irritating wrinkles arose because the formatter used FOP is still a beta version and is missing some functionality For example could not figure out how to get Roman numerals for the page number references in the preface Tables are limited to fixed downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir width format in the version used but this is documented and l m prepared to accept it for my purposes For a free system I m quite impressed with FOP cannot recommend it to companies that want professional quality typesetting yet but it s good for turning my XML copy into something readable with a reasonably accurate page count certainly expect FOP to evolve into a stronger product in coming years High end systems have more complete implementation as well as technical support and nice GUI interfaces Of course those advantages come at aprice Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team Li
537. ther way an attribute can distinguish an element is with aunique identifier a string of characters that is unique to one particular element in the document No other element may have the same identifier This gives you a way to select that one element for special treatment for cross referencinc excerpting and so on For example suppose you have a catalog with hundreds of product descriptions Each description is inside a product element You want to create an index of products with one line per product How do you refer to a particular product among hundreds The answer is to give each a uniquely identifying label produce zde9 displeav l5 incb dppie lt products DrOOuct idgd display l5 i1nch S So0ny lt product gt lt Product ZId d ispDlay l3 5cg Lbw lt produci There is no limit to how many attributes an element can have as long as no two attributes have the downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Same name Here s an example of an element start tag with three attributes lt kiosk music bagpipes color red id page 81527 gt This example is not allowed A lee Wrong lt gt team person 2 sue person jJoe person jJane gt To get around this limitation you could use one attribute to hold all the values team persons sue joe jane gt You could also use attributes with different names team personl 2 sue person2 2 joe person3 2 jane Or use
538. thods or properties are defined use the generic node methods to access data 10 9 1 3 DocumentType This class contains all the information contained in the document type declaration at the beginning of the document except the specifics about an external DTD Thus it names the root element and any declared entities or notations in the internal subset No specific methods are defined for this class but the properties are public but read only 10 9 1 3 1 Properties Here are the properties for the Document Type class name The name of the root element entities A NamedNodeMap of entity declarations notation A NamedNodeMap of notation declarations internalSubset DOM 2 only The internal subset of the DTD represented as a string publicrd DOM2 only The external subset of the DTD s public identifier systemId DOM2 only The external subset of the DTD s system identifier 10 9 1 4 Node All node types inherit from the class Node Any properties or methods common to all node types can be accessed through this class A few properties such as thevalue of the node are undefined for some node types like Element The generic methods of this class are useful in some programming contexts such as when writing code that processes nodes of different types At other times you ll know in advance what type you re working with and you should use the specific class s methods instead All properties but nodeValue and prefix are r
539. tices The two main methods event streams and object trees will be described And finally we visit the two reigning standards in XML programming SAX and DOM I will include examples in Java and Perl my two favorite programming environments both of which have excellent support for XML wrangling Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 1 Limitations Like any good technology XML does not try to be the solution to every problem There are some things it just cannot do well and it would be foolish to try to force it to do them The foremost requirement of XML is that it be universally accessible a lowest common denominator for applications This necessarily throws out many optimizations that are necessary in some situations Let s review some of these limitations e XML is not optimized for access speed XML documents are meant to be completely loaded and then used as a data source The parser is required to do a syntax check every time it reads in the markup In contrast modern databases are optimized for quick data lookups and updates e XML is not compact There is no official scheme for compressing XML XML parsers expect uncompressed text You either have to put up with large text files or you have to create a complex mechanism for compressing and decompressing on the fly which will add to your processing overhead Most proprietary applications like Microsoft
540. ties You select a typeface with the font family property as with CSS The form is a list of names each of which may be a family name like Verdana or Helvetica or a generic name that allows the formatter to choose one from a category The generic names includeserif sans serif cursive fantasy and monospace The formatter will choose a typeface in the order of font names given If the first cannot be found does not support the style or weight requested or does not contain all the glyphs necessary to render the FO properly it will move to the next font name in the list Typically you will put your favorite font family name first and the most generic one last The font family property may also be set to the function system ont which will discover the current system font and use it This gives the designer some ability to stick with the local environment Often user agents like web browsers have preference settings that allow the user to select their favorite font for use in stylesheets The properties color font size font size adjust font style font variant and font weight are all about the same as they are defined in CSS font style adds one more style to the CSS set backslant Which is like italic but leans in the other direction 8 4 4 Inlines Many block types such as paragraphs and titles contain text The text stream flows from one edge of the content rectangle to the other breaks and continues line by line until it r
541. tity that is defined in a DTD and stored in memory An ID reference is a notation that indicates a relationship with an element possessing a unique ID that resides somewhere else in the document The term reference is used to distinguish between an object or value and the thing that wants to use it See also entity entity reference relative location term An XPointer location that is identified in reference to another location such as an absolute location term or the current node See also absolute location term XPath XPointer relative URL A URL that expresses a partial location This location is understood to be relative to the current location of the reference called the base URL remote resource A resource that a simple link points to See alsolocal resource resource simple link resource A source of information In XML a resource is something that can be linked to such as an XML document a graphic file or a program root element downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The base level element of a document containing all the other elements in the document Same as document element See alsodocument document element element root node The base level node of a document containing all the nodes that comprise the document See also node rule The primary building block of a stylesheet specifying which element or elements to set a style for the selector and the st
542. to be used Transformation stylesheets are modular and can be combined with others to enhance or alter the flow oftransformation 7 5 1 Matching Nodes The XSLT patterns used insidethe match attributes of template elements are a subset of XPath expressions The first restriction on XSLT patterns is that only descending axes may be used chi1d and attribute The shorthand can be used but it s not expanded It simply would not make sense to use other axes in XSLT patterns The second difference is that paths are actually evaluated right to left not the other direction as is usual with XPath This is a more natural fit for the XSLT style of processing As the processor moves through the source tree it keeps a running list of nodes to process next called thecontext node set Each node in this set is processed in turn The processor looks at the set of rules in the stylesheet finds a few that apply to the node to be processed and out of this set selects the best matching rule The right to left processing helps the XSLT engine prioritize eligible templates downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Suppose there is a rule with a match pattern chapter section para To test this pattern the XSLT engine first instantiates the node to process as the context node Then it asks these questions in order 1 Is the context node an element of type para 2 Is the parent of this node an element of type section 3 I
543. to solve the equation with a series of values That s a sign of XML s power You can also store graphics in XML documents TheScalable Vector Graphics SVG language is used to draw resizable line art The document in Example 1 3 defines a picture with three shapes a rectangle a circle and a polygon Example 1 3 An SVG document lt xml version 1 0 standalone no gt lt DOCTYPE svg PUBLIC W3C DTD SVG 20001102 EN http www w3 org TR 2000 CR SVG 20001102 DID svg 20001102 dtd lt svg gt lt desc gt Three shapes lt desc gt rect fill green x lcm y 1cm width 3cm height 3cm gt circle fill red cx 3cm cy 2cm r 4cm gt polygon fill blue points 110 160 50 300 180 290 e ewe It s also worth noting that a document is not necessarily the same as a file Afile is a package of data treated as a contiguous unit by the computer s operating system This is called aphysical structure An XML document can exist in one file or in many files some of which may be on another system It may not be in a file at all but generated in a stream from a program XML uses special markup to integrate the contents of different files to create a single entity which we describe as alogical structure By keeping a document independent of the restrictions of a file XML facilitates a linked web of document parts which can reside anywhere That s XML markup in a nutshell The whole of the next chapter is devoted to this to
544. to the left edge Left center and right are equivalent to 0 50 and 100 respectively Values percentage length left right center inherit Default 0 backgrournd posirion horizontal Specifies where in the background an image is placed vertically Percentage and length are wit respect to the top edge Top center and bottom are equivalent to 0 50 and 100 respectively Values percentage length top center bottom inherit Default 0 8 4 3 3 Border properties The border is an optional visual component located on the block s perimeter It can be a complete rectangle or any combination of the individual edges Each edge can be styled individually for a huge number of combinations The basic pattern of a border property is border side option Where side IS top bottom left Or right and option is color width or style XSL 1 0 offers three different ways of specifying color TheRGB Red Green Blue scheme uses hexadecimal numbers in ranges of 0 to 255 combined in a triple In RGB green would be represente as 00 00 and white would be ffffff You can derive colors using functions in expressions Named colors may also be used if supported by your XSL implementation Using the valueinnerit will cause the FO to inherit this property from its parent in the FO tree The width parameter can be specified either as a named value thin medium thick or as an explici length The actual thickness of the named values is not
545. tron first proposed by Rick J elliffe of the Academia Sinicia Computing Centre in 1999 It uses XPath expressions to define validation rules and is one of the most flexible schema languages around downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 4 1 3 Do You Need Schemas It may seem like schemas are a lot of work and you d be right to think so In designing a schema you are forced to think hard about how your language is structured As your language evolves you have to update your schema which is like maintaining a piece of software There will be bugs version tracking usability issues and even the occasional overhaul to consider So with all this overhead is it really worth it First let s look at the benefits e A schema can function as a publishable specification There is simply no better way to describe a language than with a schema A schema is after all a yes or no test for document conformance It s designed to be readable by humans and machines alike DTDs are very reminiscent of Backus Naur Form BNF grammars which are used to describe programming languages Other schemas such as RELAX NG are intuitive and very easy to read So if you need to disseminate information on how to use a markup language a schema is not a bad way to do it e A schema will catch higher level mistakes Sure there are well formedness rules to protect you software from errors in basic syntax but do they go far
546. truction is part science and part art form The basic concepts are easy enough but managing a large DTD maintaining hundreds of element and attribute declarations while keeping them readable and bug free can be a challenge This section offers a collection of hints and best practices that you may find useful The next section shows a concrete example that uses these practices 4 2 4 1 Keeping it organized DTDs are notoriously hardto read but good organization always helps A few extra minutes spent tidying up and writing comments can save you hours of scrutinizing later Often a DTD is its own documentation so if you expect others to use it clean code is doubly important Organizing declarations by function Keep declarations separated into sections by their purpose In small DTDs this helps you navigate the file In larger DTDs you might even want to break the declarations into separate modules Some categories to group by are blocks inlines hierarchical elements parts of tables lists etc In Example 4 4 the declarations are divided by function block inline and hierarchical Whitespace Pad your declarations with lots of whitespace Content models and attribute lists suffer from dense syntax so spacing out the parts even placing them on separate lines helps make them more understandable Indent lines inside declarations to make the delimiters more clear Between logical divisions use extra space and perhaps a comment with a row
547. truction syntax Funny you say PIS look a lot like the XML declaration You re right the XML declaration can be thought of as a processing instruction for all XML processor 4 that broadcast general information about the document though the specification defines it as a different thing 4 This syntactic trick allows XML documents to be processed by older SGML systems they simply treat the XML declaration as another processing instruction ignoring it since it obviously isn t meant for them The target is a keyword that an XML processor uses to determine whether the data is meant for it or not The keyword doesn t necessarily mean anything such as the name of the software that will use it More than one program can use a PI and a single program can accept multiple Pls It s sort of like posting a message on a wall saying The party has moved to the green house and people interested in the party will follow the instructions while those who aren t interested won t The PI can contain any data except the combination which would be interpreted as the closing delimiter Here are some examples of valid Pls flubber pg 9 recto lt thingie gt lt xyz stop the presses gt If there is no data string the target keyword itself can function as the data A forced line break is a good example Imagine that there is a long section heading that extends off the page Rather than relying on an automatic formatter to break the title
548. ts by adding their names to a list in the stylesheet The element strip space contains a list of element names in itselements attribute This is a top level element that should be outside of any template There is also a list of elements to preserve space calledpreserve space The reason for having both these elements is that you can set up a default behavior and then override it with a more specific case For example xsl strip space elements gt xsl preserve space elements poem codelisting asciiart gt Whitespace will be normalized for elements exceptpoem codelisting and asciiart 7 6 8 Example A Checkbook This example demonstrates the concepts discussed so far First Example 7 3 is a sample XML document representing a checkbook Example 7 3 Checkbook document lt checkbook gt deposit type direct deposit lt payor gt Bob s Bolts lt payor gt lt amount gt 987 32 lt amount gt lt date gt 21 6 00 lt date gt lt description category income gt Paycheck lt description gt lt deposit gt payment type check number 980 gt lt payee gt Kimora s Sports Equipment lt payee gt lt amount gt 132 77 lt amount gt lt date gt 23 6 00 lt date gt description category entertainment gt kendo equipment lt description gt lt payment gt lt payment type atm gt lt amount gt 40 00 lt amount gt lt date gt 24 6 00 lt date gt lt description category cash gt pocket money lt des
549. ts name So it was surprising to everybody involved when XSLT became the generic transformation language of choice In retrospect it is not so surprising XSLT is a brilliantly designed language It is simple enough that its basics can be learned in an hour The elegance of XPath is very intuitive The idea of templates is downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir natural and flexible enough to apply to a wide variety of situations And because XSLT is itself an XMI application all the XML APIs and tools will happily dissect and manipulate XSLT stylesheets In this chapter will show you not only how to use XSLT to generate formatted presentational output but to use it in a wide variety of problems Once you have the transformation mindset you ll find that it s useful in so many ways Things you used to write programs to do can bedone much more succinctly and clearly in an XSLT stylesheet Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 7 2 Concepts Before we jump into specifics want to explain some important concepts that will help you understand how XSLT works An XSLT processor l Il call it anXSLT engine takes two things as input an XSLT stylesheet to govern the transformation process and an input document calledthe source tree The output is called the result tree The XSLT stylesheet controls the transformation process Whil
550. ttp www w3 org TR xquery semantics XSLT 2 0 and XQuery 1 0 Serialization athttp www w3 org TR xslt xquery serialization XQuery Use Cases at http www w3 org TR xquery use cases and XQuery 1 0 An XML Query Language at http www w3 org TR xquery Description XQuery is a query language that uses XML as a data model and is bound with XPath XQuery expressions look more like traditional query and data processing environments than XSLT and XPath and they can be used in a variety of software environments Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB B 4 Style and Transformation CSS The Cascading Style Sheets specification provides a language for assigning formats to document elements W3C Status CSS Level 2 became a W3C recommendation in May 1998 and it is published at http www w3 org TR REC CSS2 CSS Level 1 became a W3C recommendation in 1996 with a revision in January 1999 It is published at http www w3 org TR REC CSS1 Work on CSS Level 3 is ongoing and links to specifications may be found athttp www w3 org Style CSS current work Description CSS is a stylesheet language that allows authors and users to attach styles e g fonts spacing and sounds to structured documents such as HTML documents and XML applications By separating the presentation style from the content of a document CSS simplifies web authoring and site maintenanc
551. ty references into their values for you If that option is disabled the parser should create this node No explicit methods force resolution but some actions to the node may have that Side effect 10 9 1 15 Entity This class provides access to an entity in the document based on information in an entity declaratior in the DTD 10 9 1 15 1 Properties Here are the properties for the Entity class puolzcerd A public identifier for the resource if the entity is external to the document systemlid A system identifier for the resource if the entity is external to the document notationName If the entity is unparsed its notation reference is listed here 10 9 1 16 Notation Notation represents a notation declaration appearing in the DTD 10 9 1 16 1 Properties Here are the properties for the Notation class pupolroldg A public identifier for the notation systemlid A system identifier for the notation downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir 10 9 2 An Example in Perl Perl is quite different from Java It was not designed from the outset to be object oriented That functionality was added later in kind of anad hoc manner Perl is loose with type checking and rather idiomatic For these reasons it is not always taken seriously by XML pundits Yet Perl is a fixture in the World Wide Web being the original duct tape that holds web sites together It has a huge following and excel
552. tylesheets Not all languages are designed with them in mind For this purpose XML provides a generic way to embed a stylesheet downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir using a processing instruction named lt xml stylesheet gt whose syntax is shown in Figure 5 5 Figure 5 5 Syntax for a stylesheet declaration lt xml stylesheet type MIME type of The declaration begins with the processing instruction delimiter and target xml1 stylesheet 1 The PI processing instruction includes several property assignments similar to attributes two of which are required type and href type 2 Is set to the MIME type 3 of the stylesheet for CSS this is text css The value of the other property href 4 is the URL of the stylesheet 5 which can be on the same system or anywhere on the Internet The declaration ends with the closing delimiter 6 Here s how it would be used in a document lt xml version 1 0 gt xml stylesheet type text css href bookStyle css gt lt book gt lt title gt Tom Swift s Aerial Adventures lt title gt lt chapter gt lt title gt The Dirigible lt title gt Using a processing instruction forthis purpose is smart for a few reasons First it doesn t pollute the language with an extra element that has to be declared in a DTD Second it can be ignored by processors that don t care about stylesheets or older ones tha
553. u a rich assortment of options For example we could rewrite the second template in Example 7 2 like so lt xsl template match manual gt Gages downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt head gt lt title gt Parts List lt title gt lt head gt lt body gt lt hl gt Parts List lt hl gt xsl apply templates select parts list gt lt body gt entm lt xsl template gt Now only the parts list element will be processed All other children ofmanual including its attributes and the instructions element would be skipped Alternatively you can skip a particular element type like this lt xsl template match manual gt 6 0 lt head gt lt title gt Assembly Steps lt title gt lt head gt Dodgy gt lt hl gt Assembly Stepsc hl xsl apply templates select not parts list gt lt body gt lt 7 cil lt xsl template gt And everything but the parts 1ist element will be handled While it is possible to set theselect attribute to point to an ancestor of the current node be very careful about doing this as it might set up an infinite loop 7 5 4 2 The for each instruction The or each element creates a template within a template Instead of relying on the XSLT engine to find matching templates this directive encloses its own region of markup Inside that region the context node set is redefined to a different node set again determined by aselect attribute Once o
554. ugh ancestors down through descendants or linearly through siblings Table 6 1 lists all the types of node axes Table 6 1 Node axes Axis Axistype o Mathes All nodes above the context node including the parent grandparent and so on up Ancestor to the root node m um Teen OO ancestor node plus the context node m FOR of the context node Child Children of the context node 00000 of the context node Children of the context node plus their children and so on down to the leaves of Descendant the subtree me descendant node plus the context node Nodes that follow the context node at any level in the document This does not Following include any descendants of the context node but does include its following siblings and their descendants Following Nodes that follow the context node at the same level i e that share the same sibling parent as thecontext node downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Axis type Matches Namespace Al the namespace nodes of an element Parent The parent of the context node Nodes that occur before the context node at any level in the document This does not include any descendants of the context node but does include its preceding siblings and their descendants Preceding Nodes that occur before the context node at the same level i e that share the sibling same parent as the context node Self The context n
555. ules abstract Boolean conversion cascading character escaping CSS matching syntax troubleshooting names numeric expressions precedence string expressions stylesheets well formedness XSLT default modes rules stylesheet CSS properties declaration Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir Team LIB A B C D E F G H 1 J K L EM N O P IQ R S T U IV W X SAX Simple API for XML 2nd 3rd Java web site information Scalable Vector Graphics SVG language Schema for Object Oriented XML SOX schemas comparing documents DTDs 2nd customizing declarations document prologs narrative documents need for overview of RELAX NG 2nd attributes data typing elements modularity name classes named patterns namespaces Schematron types of DTDs RELAX NG Schematron W3C XML Schema validation W3C XML Schema Schematron 2nd 3rd schemes URLs XPointer science standards searching nodes ranges sections See also flow 2nd conditional 2nd selection character encodings of parsers selectors 2nd CSS matching rules downloaded from lib eommolketab ir downloaded from fib ommolkcetftab ir pseudo element sibling sequences page masters page sequence master objects serialization dictionaries server side processing SGML shortcuts XPath shorthand xpointers sibling selectors Simple API for XML
556. ults a table in memory for something with which to replace the marker It replaces the entity reference with the appropriate replacement text or markup then resumes parsing just before that point so the new text Is parsed too Any entity references inside th replacement text are also replaced this process repeats as many times as necessary predefined Recall from Section 2 3 2 earlier in this chapter that an entity reference consists of an ampersand amp the entity name and a semicolon The following is an example of a document that declares three general entities and references them in the text downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt xml version 1 0 gt lt DOCTYPE message SYSTEM xmlstuff dtds message dtd lt ENTITY client Mr Rufus Xavier Sasperilla gt lt ENTITY agent Ms Sally Tashuns lt ENTITY phone number 617 555 1299 number message lt opening gt Dear amp client opening lt body gt We have an exciting opportunity for you A set of ocean front cliff dwellings in Pi amp 24l ata Mexico have been renovated as time share vacation homes They re going fast To reserve a place for your holiday call amp agent at amp phone Hurry amp client Time is running out lt body gt lt message gt The entities amp client amp agent and amp phone are declared in the internal subset of this document discussed in Section 2
557. uns out or hits the bottom of the block Embedded in these lines are elements that override the default font styles or ge downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir replaced with generated content This is the realm of inline formatting 8 4 4 1 The inline FO The inline FO Is a generic container of text that allows you to override prevailing text properties It Shares all of the font and color properties of blocks and some spacing properties as well including space before and space after In the following example the XSLT template maps the element emphasis to an inline element that styles its content green and italic lt xsl template match emphasis gt lt fo inline font style italic color green gt xsl apply templates lt Totsnline gt lt xsl template gt Here is another example It formats text in Superscript by shrinking text to 60 of the default size in the block and raising it with the top of the line lt xsl template match Superscript gt lt fo inline font size 60 vertical align super gt xsl apply templates lt fo inline gt lt xsl template gt 8 4 4 2 Inline formatting without containment Using inline requires that you know where the content to be styled begins and ends There are times however when you do not have any way to know in advance the extent of content to be styled For example your design may call for the first line of a paragraph to r
558. upport in Stylesheets CSS and XSLT both have tests that let you specify different behaviors depending on the language of your audience For example your document may contain an element that renders as a note with a stylesheet generated title CAUTION In a German translation you may want it to say VORSICHT instead The following sections describe how this conditional behavior can be implemented 9 3 2 1 CSS and the lang pseudo class Cascading Style Sheets Level 2 includes a pseudo class for adding language options to a stylesheet It determines the language from the xm1 lang attribute or from the encoding attribute from the XML declaration For example the following rule changes the color of Frenchphrase elements to red DnhrasseclaHgirr colors red j 9 3 2 2 XSLT and the lang function XSLT also pays attention to language In Chapter 7 we discussed Boolean functions and their roles in conditional template rules One important function islang whose value is true If the current node s language is the same as that of the argument Consider the following template lt xsl template match para gt x56 Cnoose xsl when test lang de gt lt h1 gt ACHTUNG lt h1 gt xsl apply templates lt if gt lt xsl otherwise gt chl ATTENTION 7hI xsl apply templates lt xsl otherwise gt lt xsl template gt The XSLT template rule outputs the word ACHTUNG if the language isade or ATTENTION
559. use the binary representation of UTF 8 byte strings to show how certain bits are used to pad the bytes The xxx portion is to be filled with bits of the character code number when converted to binary and the rightmost bit is the least significant Table 9 2 UTF 8 Encoding Algorithm for UCS UCS character number UTF 8 byte string in binary U 00000000 U 0000007F OXXXXXXX U 00000080 U 000007FF 110xxxxx lOXxxxxx U 00000800 U 0000FFFF 1110xxxx lO0xxxxxx lOxxxxxx U 00010000 U OO1FFFFF 11110xxx 10xxxxxx 10xxxxxx 10Xxxxxx U 00200000 U O3FFFFFF 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10Xxxxxx U 04000000 U 7FFFFFFF 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx l10Xxxxxx To encode the Unicode character 0 x03CO the Greek small letter pi first compose it in binary 0011 1100 0000 We select the second row from the table and pack the bits into x slots to get in binary 11001111 10000000 So the byte sequence in UTF 8 for this character is OxCF 0x80 You can see from this algorithm that the only time a byte sequence contains bytes with values between 0x00 and Ox7F is when they are one byte in length and represent the ASCII characters with those code positions Other byte sequences range from OxCO to OxFD for the first byte and from 0x80 to OxBF in following bytes Keeping the first and following bytes in different ranges makes allows for error detection and easy resynchronization in the event of missing bytes du
560. utput redirection the command span class command cat filel file2 amp gt filel span will cause the original data in filel to be destroyed lt p gt lt J din div class section gt CH229SgE ALSO h25 lt ul gt lt li gt lt a hrefe head html headil e as li eli a href more html nmorei l sc li lt li gt lt a href pr html 5pr 1 a li lt li gt lt a hrer tail html stalli ili e ase l11 lt li gt lt a href yis html gt gt vis 1 lt a gt lt li gt lt ul gt lt p gt Rob Pike lt span class citation gt UNIX Style or cat v Considered Harmful lt span gt USENIX Summer Conference Proceedings 1983 lt I p gt lt div gt downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir div class section SDhHISTOBYS NI dep A i cat i utility appeared in Version 6 AT amp T UNIX Sp lt p gt 3rd Berkeley Distribution May 2 1995 p lt div gt lt body gt lt html gt Example 5 2 is a CSS stylesheet for this document Example 5 2 A CSS stylesheet for an XHTML document GLOBAL SETTINGS body background color aa6 Lonrt ramalvi serait BLOCKS section margin lem padding 5em background color wheat hls nee Mo 3 font family sans serif dE 4 backsgrounce OOIlO0rs tarn code padding 1em border thin solid gray font family monospace font weight bold INLINES SDOILSLLODn 1 color
561. utside the or each the old context node set is reinstantiated Consider this template lt xsl template match book gt lt xsl for each select chapter gt lt xsl text gt Chapter lt xsl text gt lt xsl value of select position gt lt xsl text gt lt xsl text gt lt xsl value of select title gt lt xsl text gt lt xsl text gt xslt for each xsl apply templates lt xsl template gt It creates a table of contents from a DocBook document The or each element goes through the book and retrieves every child element of type chapter This set becomes the new context node set downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir and within the or each we know nothing about the old context nodes The first value of element outputs the string value of the XPath expressionposition which is the position in the set of the chapter being evaluated in this iteration through the loop The next value of Outputs the title of this chapter Note that it is a child ofchapter not book Since the output of this is plain text had to insert the secondtext element to output a newline character We will cover formatting and whitespace issues later in the chapter The result of this transformation would be something like this Chapter 1 Teething on Transistors My Early Years Chapter 2 Running With the Geek Gang Chapter 3 My First White Collar Crime Chapter 4 Hacking the Pentagon
562. value gt lt value gt none lt value gt lt choice gt c lattrsbute attribute name pid gt downloaded from lib ommolketab ir downloaded from lib ommolketab ir lt data type integer gt lt param name minInclusive gt 1 lt param gt lt param name maxInclusive gt 999999 lt param gt lt data gt lt Sceribuce gt lt element name age gt data type integer gt lt param name minInclusive gt 0 lt param gt lt param name maxInclusive gt 200 lt param gt lt data gt lt element gt lt element name gender gt choice lt value gt male lt value gt lt value gt gender lt value gt lt choice gt lt element gt lt element name name gt lt interleave gt lt element name first gt lt text gt lt element gt lt element name last gt lt text gt lt element gt lt optional gt lt choice gt lt element name junior gt lt empty gt lt element gt lt element name senior gt lt empty gt lt element gt choice optional interleave lt element gt lt interleave gt lt element gt lt oneOrMore gt lt element gt This schema certainly looks a lot cleaner than the W3C Schema version Enumerations and complex types are much more clear The grouping structures are very easy to read Personally thinkRELAX NG is just more intuitive all around Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir T
563. variously called a stylesheet or transformation script There are many reasons to transform XML Most often it is to extend the reach of a document into new areas by converting it into a presentational format Alternatively you can use a transformation to alter the content such as extracting a section or adding a table of numbers together It can even be used to filter an XML document to change it in very small ways such as inserting an attribute into a particular kind of element Some uses of transformation are e Changing a non presentational application such as DocBook into HTML for display as web pages e Formatting a document to create a high quality presentational format like PDF through the XSL FO path e Changing one XML vocabulary to another for example transforming an organization specific invoice format into a cross industry format e Extracting specific pieces of information and formatting them in another way such as constructing a table of contents from section titles e Changing an instance of XML into text such as transforming an XML data file into a comma delimited file that you can import into Excel as a spreadsheet e Reformatting or generating content For example numeric values can be massaged to turn integers into floating point numbers or Roman numerals as a way to create your own numbered lists or section heads e Polishing a rough document to fix common mistakes or remove unneeded markup preparing it for
564. w to do it with conditional sections First the DTD must be written to allow parameter entity switching IENTITY default polyhedron INCLUDE gt lt sdefault polyhedron lt ELEMENT polyhedron sidet anglet gt J gt Now in your document you declare this DTD as your external subset then redeclare the parameter entity default polyhedron in the internal subset lt DOCTYPE picture SYSTEM shapes dtd lt ENTITY default polyhedron IGNORE gt lt ELEMENT polyhedron side side sidet angle angle anglet gt gt Since the internal subset is read before the external subset the parameter entity declaration here takes precedence over the one in the DTD The conditional section in the DTD will get a value of IGNORE Masking the external element declaration forpolyhedron The element declaration in the internal subset is valid and used by the parser Conditional sections can be nested but outer sections override inner ones So if the outer section is set to IGNORE its contents including any conditional sections inside it are completely turned off regardless of their values For example lt INCLUDE lt text in here will be included gt lt IGNORE lt text in here will be ignored gt NP i gt lt IGNORE lt text in here will be ignored gt lt INCLUDE Warning this stuff will be ignored too gt gt 117 Public DTDs often make heavy use of
565. width and height dimensions margins and a name to reference later with a flow lt xsl template match gt iG age OO we ro layout master ser lt fo simple page master master name the only page type page height 4in page width 4in margin top 0 51in margrn bottom 0 51n margin left 0 5in margin right 0 5in gt fo region body lt fo simple page master gt fo layout master set downloaded from lib ommolketab ir downloaded from fib ommolkcetftab ir xsl apply templates fo root lt xsl template gt lt The first block element where we insert the document flow lt page sequence gt sets up an instance of the page type we defined above flow contains all the stackable block objects shaping them so they fit in the page region we defined The flow contains a block that defines font name size text alignment and surrounds its content in a 0 25 inch buffer of padding lt xsl template match mydoc fo page sequence master reference the only page type rto rlow Iflow name xsl region body SIOSDIOOX font family helvetica sans serif font size 24pt text align 2 center padding 0 25in xsl apply templates eI ToSDlOGER clrostlow fo page sequence lt xsl template gt 1 The second block element a title is bold 10 point type and inserts 1 em of space below itself lt xsl template match title gt SIO
566. will fit into you know the key will unlock the door but you have no idea how it really works Specifically the outward appearance makes it easy to write extensions to legacy modules so they can comply with the standard but it does not guarantee efficiency or speed DOM is a very large standard and you will find that implementations vary in their level of compliance To make things worse the standard has not one but two soon to be three levels DOMI has been around since 1998 DOM2 emerged more recently and they re already working on a third The main difference between Levels 1 and 2 is that the latter adds support for namespaces If you aren t concerned about namespaces then DOM1 should be suitable for your needs 10 9 1 Class Interface Reference In this section describe theinterfaces specified in DOM 10 9 1 1 Document downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir The Document Class controls the overall document creating new objects when requested and maintaining high level information such as references to the document type declaration and the root element 10 9 1 1 1 Properties Following are the properties for theDocument class doctype Document Type Declaration DTD documentElement The root element of the document 10 9 1 1 2 Methods Here are the methods for the Document class createElement createTextNode createComment createCDATASection createProcessingInstruction
567. with a language there are many needs you don t know about until you start using it creating a bit of a bootstrapping problem To make the decision easier think about it this way A schema is basically a quality control tool If you are reasonably certain that your documents are good enough for processing then you have no need for schemas However if you want extra assurance that your documents are complete and structurally sound and the work you save fixing mistakes outweighs the work you will spend maintaining a schema then you should look into it One thing to consider is whether a human will be involved with producing a document No matter how careful we are we humans tend to make a lot of mistakes Validation can find those problems and save frustration later But software created documents tend to be very predictable and probably never need to be validated The really hard question to answer is not whether you need a schema but which standard to use There are a few very valuable choices that will be describing in the rest of the chapter hope to provide you with enough information to decide which one is right for your application Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 4 2 DTDs The original XML document model is the Document Type Definition DTD DTDs actually predate XML they are a reduced hand me down from SGML with the core syntax almost completely int
568. with a subtree The parser scans through the stream until it sees the part that you want then switches to tree building mode One example is the Perl module XML Twig by Michel Rodriguez Before parsing you tell the parser which twigs you want it to find for example every section element in a DocBook book It will return a tree one at a time for processing nimbly side stepping the problem of storing the whole book in memory at the same time 10 10 4 Data Binding downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Some developers don t need direct access to XML document structures they just want to work with objects or other data structures Data binding approaches minimize the amount of interaction between the developer and the XML itself Instead of creating XML directly an API takes an object and serializes it Instead of reading an XML document and interpreting its parts an API takes an XML document and presents it as an object Data binding processing tends to focus on schemas which are used as the foundation for describing the XML representing a particular object The type and structure information used in the schema provides the data binding processor with information about both the XML documents and the objects and a simple mapping between them suffices for a large number of cases Data binding is also at the heart of web services a set of technologies for using XML to send information over a network
569. with those unexpected nasty Situations like a badly formed document or an entity that cannot be resolved Unless you want an angry mob of users breaking down your door you had better put in some good error checkingcode 10 8 2 A Java Example Element Counter In this first example we willuse SAX to create a Java program that counts elements in a document We start by creating a class that manages the parsing process shown inExample 10 2 Example 10 2 Contents of SAXCounter java downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir import org xml sax XMLReader import org xml sax helpers XMLReaderFactory inport OCXIJg xnl sax lnputoources import java io FileReader public class SAXCounter public SAXCounter j public static void main String args throws Exception XMLReader xr XMLReaderFactory createXMLReader SAXCounterHandler h new SAXCounterHandler create a handler xr setContentHandler h register it with the driver FileReader r new FileReader args 0 Xr puarsei qnew inputsSonrcstr J7 This class sets up the SAX environment and requests a SAX driver from the parser factory XMLReaderFactory Then it creates a handler and registers it with the driver via the setContentHandler method Finally it reads a file Supplied on the command line and parses it Because am trying to keep this example short will not register an error handler although ordinarily th
570. wnloaded from fib ommolkcefab ir Team LiB 8 2 A Quick Example To give you a good overview of thewhole process let us take a look at a short quick example This humble XML document will be the source lt mydoc gt lt title gt Hello world lt title gt lt message gt I am lt emphasis gt so lt emphasis gt clever lt message gt lt mydoc gt The first step in using XSL FO is to write an XSLT stylesheet that will generate a formatting object tree Example 8 1 is a very simple for XSL FO stylesheet There are five templates in all The first creates a page master an archetype of real pages that will be created as text is poured in setting ut the geometry of content regions The second template associates a flow object with the page master The flow is like a baggage handler throwing suitcases into a compact space that fits the geometry set up in the page master The rest of the templates create blocks and inlines to be stacked inside the flow Example 8 1 An XSLT stylesheet to turn mydoc into a formatting object tree lt xml version 1 0 gt xsl stylesheet xmlns xsl http www w3 org 1999 XSL Transform xmlns fo http www w3 org 1999 XSL Format version 0 gt xsl output method 2 xml x 1 The root node where we set up a page with a single region layout master set may contain many page masters but here we have defined only one simple page master sets up a basic page type with
571. wnloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Like parameters a variable reference has a required dollar sign prefix and when referenced in non XPath attribute values it must be enclosed in curly braces 3 Variables can be used in other declarations but be wary of creating looped definitions Here is a dangerous mutually referential set of variable assignments 1 ASKING FOR TROUBLE gt lt xsl variable name thingl select Sthing2 gt lt xsl variable name thing2 select Sthingl gt Variables can be declared outside of templates where they are visible by all or inside one where its scope is limited to that template The following template creates a bracketed number to mark a footnote and makes it a link to the footnote text at the end of the page The number of the footnote is calculated once but used twice lt xsl template match footnote gt lt xsl variable name fnum select count preceding footnote ancestor chapter 1 gt lt a gt lt xsl attribute name href gt lt xsl text gt FOOTNOTE lt xsl text gt xsl number value Sfnum format 1 gt xsl attribute exualspextole xelesbeuL xsl number value Sfnum gt exsletext e xsSl texr lt a gt lt xsl template gt Instead of performing the calculation in the content of the element did it inside aselect attribute Using select is generally better because it doesn t incur the cost of
572. would be a much more confusing place From Eli Whitney s interchangeable gun part to standard railroad gauges the industrial revolution couldn t have happened without them The best kind of standard is one that is open An open standard is not owned by any single company or individual It is designed and maintained based on input from the community to fit real needs not to satisfy a marketing agenda Therefore it isn t subject to change without notice nor is it tied to the fortune of a company that could disappear in the next market downturn There are no licensing fees nondisclosure agreements partnerships or intellectual property disputes It s free public and completely transparent The Internet was largely built upon open standards IP TCP ASCII email HTML Telnet FTP they are all open even if they were funded by private and government organizations Developers like open standards because they can have a say in how they are designed They are free to use what works for them rather than be tied to a proprietary package And history shows that they work remarkably well XML is an open standard It was designed by a group of companies organizations and individuals called the World Wide Web Consortium W3C The current recommendation was published in 1998 with a second edition published in 2000 although a new version 1 1 which modifies the list of allowable characters is currently in the draft stage The specification is free to
573. wy center xmlns flavor http www deliciouscandy com caramel gt lt flavor walnut gt lt flavor chewy gt lt flavor chocolate shell gt How an XML processor reacts when entering a new namespace depends on the application For a wel document it may trigger a shift in processing from one kind e g normal web text to another e g math formulae Or as in the case of XSLT it may use namespaces to sort instructions from data where the former is kind of like a meta markup Namespaces are a wonderful addition to XML but because they were added after the XML specification they ve created a rather tricky problem Namespaces do not get along with DTDs If you want to test the validity of a document that uses non implicit namespaces chances are the test will fail This is because there is no way to write a DTD to allow a document to use namespaces DTD want to constrain a document to a fixed set of elements but namespaces open up documents to an unlimited number of elements The only way to reconcile the two would be to declare every fully qualified name in the DTD which would not be practical Until a future version of XML fixes this incompatibility you will just have to give up validating documents that use multiple namespaces 2 4 4 Whitespace You ll notice in my examples like to indent elements to clarify the structure of the document Spaces tabs and newlines collectively called whitespace characters are often used to make a
574. xample you can see a pattern some tags function as bookends marking the beginning and ending of regions while others mark a place in the text Even the simple document here contain quite a lot of information Boundaries A piece of text starts in one place and ends in another The tags lt telegram gt and lt telegram gt define the start and end of a collection of text and markup Roles What is a region of text doing in the document Here the tagS lt name gt and lt name gt give an obvious purpose to the content of the element a name as opposed to any other kind of inline text such as a date or emphasis Positions Elements preserve the order of their contents which is especially important in prose documents like this Containment The nesting of elements is taken into account by XML processing software which may treat content differently depending on where it appears For example a title might have a different font size depending on whether it s the title of a newspaper or an article Relationships A piece of text can be linked to a resource somewhere else For instance the tag graphic creates a relationship link between the XML fragment and a file named me eps The intent is to import the graphic data from the file and display it in this fragment An important XML term to understand is document When you hear that word you probably think of a sequence of words partitioned into paragraphs sections and chapters
575. xmlns foo 2 http www mystuff com commentary coprTonmal s lt attribute name xml space gt lt choice gt lt value gt default lt value gt lt value gt preserve lt value gt lt choice gt attribute optional zeroOrMore choice text element name foo comment gt lt text gt lt element gt choice zeroOrMore element Add the attribute ns to any element or attribute declaration to set an implicit namespace context For example this declaration downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir lt element name vegetable ns http www broccoli net xmlns http relaxng org ns structure 1 0 lt empty gt lt element gt would match either of these lt food vegetable xmlns food http www broccoli net gt vegetable xmlns http www broccoli net but fail to match these vegetable food vegetable xmlns food http www uglifruit org The namespace setting is inherited allowing you to set it once at a high level Here the inner element declarations for title and body implicitly require the namespace http howtowrite info lt element name 2 report ns http howtowrite info xmlns http relaxng org ns structure 1 0 lt element name title gt lt text gt lt element gt lt element name body gt lt text gt lt element gt lt element gt 4 4 5 Name Classes A name class is any pattern that substitu
576. xs1 prefix the markup is treated as data and carried to the output document as is Some of the instruction elements likexsi apply templates control the flow of processing making the XSLT processor recurse through the source document lookingfor more downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir elements to transform In some ways XML schemas are similar to XSLT They use templates to describe parts of documents as they should be instead of as they will be In other words a schema is a test to determine whethei a document can be labeled a valid instance of a language Templates are a good design mechanism for documents describing documents because they are modular and easy to understand Instead of looking at the whole document you only have to imagine one element at a time Templates can be imported from other files and mixed to add more flexibility XML schemas will be discussed in greater detail inChapter 4 while XSLT will be discussed in greater detail in Chapter 7 Team LIB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB Chapter 4 Quality Control with Schemas Up until now we have been talking about the things all XML documents have in common Well formedness rules are universal ensuring perfect compatibility with generic tools and APIs This syntax homogeneity is a big selling point for XML but equally important is the need for ways to
577. xsl text gt CI bou IA lt xsl text gt s lt xsl text gt lt xsl value of select amount gt cle xsl text from an ATM for xsl text lt xsl value of select description gt lt xsl text gt lt xsl text gt lt p gt lt xsl template gt lt xsl template match payment gt lt p gt lt xsl value of select position gt lt xsl text gt On lt xsl text gt lt xsl value of select date gt lt xsl text gt vou paid lt xsl text gt ae ee A SP lt xslrtext gt s lt xslstext gt lt xsl value of select amount gt pasti lt xsl text gt to lt xsl text gt lt j gt lt xsl value of select payee gt n xolietert for x amp lrtext lt xsl value of select description gt lt xsl text gt lt xsl text gt eu lt xsl template gt lt xsl template match deposit gt lt a gt lt xsl value of select position gt xsl text On lt xsl text gt lt xsl value of select date gt xsl text lt xsl text gt EIE cC lt xsl text gt s lt xsl text gt lt xsl value of select amount gt E pee IIS xsl text was deposited into your account by xsl text lt i gt lt xsl value of select payor gt lt i gt lt xsl text gt lt xsl text gt downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir lt 7 o gt lt xsl template gt lt xsl stylesheet gt Example 7 5 shows the resulting HTML file Figure 7 1 shows how it look
578. xt set of declarations lt ELEMENT date year month day lt ELEMENT year PCDATA gt lt ELEMENT month PCDATA gt lt ELEMENT day PCDATA gt The PCDATA literal represents character data Specifically it matches zero or more characters Any element with a content model PCDATA can contain character data but not elements So the elements year month and day are what you might call data fields The date element in contrast must contain elements but not character datal3l 3 Whitespace is allowed to make the markup more readable but would be ignored for the purpose of validation Now for the address bit address Is a container of elements just like aate For the most part its subelements are plain data fields their content is character data only but one element has mixed content street Here are the declarations lt ELEMENT address street city county country postalcode gt lt ELEMENT street PCDATA unit gt lt ELEMENT city PCDATA gt lt ELEMENT county PCDATA gt lt ELEMENT country PCDATA gt lt ELEMENT postalcode PCDATA gt lt ELEMENT unit PCDATA gt The declaration for street follows the pattern used by all mixed content elements The PCDATA must come first followed by all the allowed subelements separated by vertical bars The asterisk here is required It means that there can be zero or more of whatever comes before it The upshot is that character data Is optional along w
579. xt value of the first node is used as the string Boolean The string is true If the expression is true otherwise false Numb The string value is the number as it would be printed For example string 1 nea 5 9 evaluates to the string 3 Result tree The string value is the concatenation of the text values of all the nodes in the fragment fragment Functions that return string values are listed in Table 6 13 Table 6 13 Functions that create strings Function o0 Retums 00000000 t st ri dtd P is A string that is the concatenation of the string arguments A string containing the number formatted according to pattern The optional decimal format argument points to a format declaration which assigns special characters like the grouping character which separates groups of digits in large numbers for readability In XSLT this format declaration would be the value of thename attribute in a decimal format element format number number pattern decimal format downloaded from lib ommolketab ir downloaded from lib ommolketab ir Function Returns The string with leading and trailing whitespace removed and all other strings of whitespace characters replaced with single spaces The value of the context node is used if the argument is left out substring string A Substring of the string argument starting offset characters from the offset range beginning and ending range characters from the of
580. y 50 r 5 fill yellow stroke brown gt circle cx 57 cy 50 r 5 fill yellow stroke brown gt text x 25 y 25 fill purple font size 18pt font weight bold font style italic gt Zonky lt text gt text x 40 y 85 fill white font family sans serif Z2 1 text lt svg gt 1l Message gt lt div class message gt lt p gt Thanks for watching my robot pal lt span class name gt Zonky lt span gt while I m away He needs to be recharged lt em gt twice a day lt em gt and if he starts to get cranky I ll be back soon after I ve tracked down that evil give him a quart of oil mastermind span class villain gt Dr Indigo Riceway lt span gt lt p gt DAP VD Newton s theory of gravitation Your homework for this week is to prove MathML Bguabtlon gt math xmlns http www w3 org 1998 Math MathML lt mrow gt lt mi gt F lt mi gt lt mo gt lt mo gt lt mi gt G lt mi gt lt more Lnvisi bleTimes lt 7 mos smira lt mrow gt lt mi gt M lt mi gt More liv si blelimess lt mo gt lt mi gt m lt mi gt lt mrow gt lt mrow gt lt msup gt emi cre mi mn 2 mn lt msup gt lt mrow gt lt mErac gt lt mrow gt lt math gt lt p gt lt J aLr dave downloaded from fib ommolkcetftab ir downloaded from fib ommolkcefab ir eb lt html gt Figure 1 9 Amaya showing a document with XHTML SVG and Mathh
581. y look pretty good while sites likehttp csszengarden com show off more CSS capabilities Although originally designed to augment HTML CSS can complement XML as well In this chapter we will see how it can be used for web pages as well as XML documents for human consumption Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 5 1 Stylesheets XML and stylesheets go together like naked people and clothes Let s take a moment to familiarize ourselves with the general concepts behind stylesheets First why do you want them Second how do they work Finally are there limitations and what can we do about them 5 1 1 Why We Need Them can rant about why it simportant to keep information pure and separate presentation into stylesheets but this would ignore a critical question if it s easier to write in presentational markup and admit that it is why would you want to bother with stylesheets After all the Web itself testifies to the fact that presentational markup is working quite well for what it was designed to do For that matter what s wrong with plain text If you are already familiar with the sermon then skip this section because I m going to preach the religion of stylesheets now XML was inspired to a large extent by the limitations of HTML Tim Berners Lee the inventor of HTML always had stylesheets in mind but for some reason they had been forgotten in the huge
582. y other node type except the root node In a tree it would be the point where two branches meet Or if it is an empty element it would be a leaf node Attribute For simplicity s sake XPath treats attributes as separate nodes from their element hosts This allows you to select the element as a whole or merely the attribute in that element using the same path syntax An attribute is like an element that contains only text Text A region of uninterrupted text is treated as a leaf node It is always the child of an element An element may have more than one text node child however if it is broken up by elements or other node types Keep that in mind if you process text in an element you may have to check more than one node Comment Though technically it does not contribute anything to the content of the document and most XML processors just throw it away an XML comment is considered a valid node This may be a way to express a document in such a way that it can be reconstructed down to the character although as will explain later this is not strictly possible And who knows maybe you want downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir to keep the comments around Processing instruction Like comments a processing instruction can appear anywhere in the document under the root node Namespace You might think it strange that a namespace declaration should be treated differently from an attribute
583. y problem for legacy programs that were programmed for 8 bit character sets Some encodings such as UTF 8 repackage 16 bit and 32 bit characters as strings of octets so that they can be handled safely with older programs These characters may not be rendered correctly but at least they will pass through unmolested and without crashing the software For example the text editor like to use on my documents is Emacs Emacs does not understand Unicode yet but it can open and edit UTF 8 encoded files and treat the unknown high characters in a way that can see andwork around 9 1 3 Unicode and UCS Compared to most other alphabets and scripts around the world the English alphabet is extremely compact While it may be suitable for English speakers it lacks too many pieces for use with other languages Most languages based on the Latin alphabet use ligatures and accents not found in ASCII And Latin is just a minority among the many writing systems around the world Many attempts to accommodate other alphabets simply packed new characters into the unused 128 characters from the extra bit in 8 bit ASCII Extensions specializing in everything from Greek to Icelandic appeared Computer manufacturers also made up their own versions of 8 bit character sets The result was a huge number of specialty character sets Many of these have been standardized such as ISO 8859 which includes character sets like the popular ISO Latin 1 Cyrillic Arabic Hebrew a
584. y use a URL The namespace has to be assigned some kind of unique identifier URLs are unique They often contain information about the company or organization So it makes a good candidate Still many have made the point that URLs are not really meant to be used as identifiers Resources are moved around often and URLs change But since no one has found a better method yet it looks like namespace assignments to URLs is here to stay To include an element or attribute in a namespace other than the implicit namespace you must use the form in Figure 2 13 This is called a fully qualified name To the left of the colon 2 is the namespace prefix 1 and to the right is thelocal name 3 downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Figure 2 13 Fully qualified name namespace prefix local name O o Namespaces only affect a limited area in the document The element containing the declaration and all of its descendants are in the scope of the namespace The element s siblings and ancestors are not It is also possible to override a namespace by creating another one inside it with the same name In the following example there are two namespaces namedflavor yet the chocolate shell element is in a different namespace from the elementchewy center The element flavor walnut Is in the latter namespace xfl vor ch ocolate shell xmlnssflavors http www deltoionscandy com chooeolate s flavor che
585. yle to be applied the properties declaration See also stylesheet Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB S SAX Simple API for XML An event driven application programming interface for manipulating XML documents with Java The API describes a flat document model no object hierarchy or inheritance that then allows for quick document processing scheme A prefix to a URL that establishes the address pattern and protocol to be used For example the prefix http specifies that the hypertext transfer protocol is to be used as in the following URL http www oreilly com See also URL selector The part of a CSS stylesheet rule that determines the elements to which the style is applied See also CSS rule stylesheet SGML Standard Generalized Markup Language An international standard ISO 8879 that specifies rules for the creation of platform independent markup languages for electronic texts simple link The simplest form of a link consisting of an element in a document the local resource that specifies a target or the location of the remote resource See alsolocal resource remote resource standards body An organization that works to produce industry wide technical standards downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir stylesheet A set of formatting instructions either in a separate file or groupe
586. you a little closer to the node you want to locate It s sort of like giving directions to a restaurant Go to Davis Square head down College Avenue at the Powderhouse rotary turn left and you ll see a great Vietnamese restaurant For example to get from the root node to apara element inside a section downloaded from lib ommolketab ir downloaded from lib eommotketab ir inside a chapter inside a book a path might look like this book chapter section para This syntax can be verbose XPath defines somehandy shortcuts as listed in Table 6 3 Table 6 3 Location path shortcuts Pattern Matches nes Matches an attribute named role This is equivalent to attribute role The context node This is equivalent toself node Matches the document element Any location path that starts with slash is an absolute path with the first step representing the root node The next step is which matches any element paren Koa Matches all paras that follow the parent of the context node giplLing para Matches the parent node The double dot is shorthand for B parent node Matches any element of type para that is a descendant of the current para node The double slash is shorthand for descendant or seltfisnode Matches any para descending from the root node In other words Loses it matches all paras anywhere in the document A location path starting with a double slash is a
587. ype xs integer gt The date element is a complex type because it has special requirements that you must explicitly define In this case the type is a group of three elements in any order referred to by name using the ref attribute These referred elements are defined at the bottom to be of typeinteger It is possible to refine the date even further Although the schema will guarantee that each of the downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir subfields year month and day are integer values it will allow some values we don t want For example 125724 is a valid integer but we wouldn t want that to be used formonth The way to control the range of a data type is to usefacets A facet is an additional parameter added to a type definition You can create a new data type for the lt month gt element like this lt xs simpleType name monthNum gt xs restriction base xs integer gt xs minlInclusive value 1 gt lt xs maxInclusive value 12 gt lt Kor restriction lt xs simpleType gt lt xs element name month type monthNum gt Here we created a named type and named itmonthNum Named types are not bound to any particular element so they are useful if you ll be using the same type over and over In this type definition is an xs restriction element from which we will derive a more specific type than the loose xs integer Inside are two facets minInclusive and maxInclusive sett
588. ype and register it with the parser as a call back something that gets called when a given event occurs Streams are good for a wide variety of XML processing tasks Programs that use streams will be fast and able to handle very large documents The code will be simple and fit the source data like a glove Where streams fail are situations in which data is so complex that it requires a lot of searching downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir around For example XSLT jumps from element to element in an order that may not match the lexical order at all When that is the case we prefer to use the treemodel Team LiB downloaded from lib ommolketab ir downloaded from fib ommolkcefab ir Team LiB 10 3 Trees and Objects The tree method is luxurious in comparison to streams To use an analogy think of a stream generator as a hose gushing out XML A tree is that same XML frozen into an ice sculpture You can peruse it at your leisure returning to any point in the document when you need it This structure requires more resources to build and store so you will only want to use it when the stream method cannot help There are many reasons why a tree structure representing a piece of XML is a handy thing to have Since a tree is acyclic it has no circular links you can use simple traversal methods that won t get stuck in infinite loops Like a filesystem directory tree you can represent

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