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1. Dispose of entry record buffer Clear report format buffer Print installed report formats Get report data r Search criteria in output yes no Page numbers desired yes no if yes then enter starting page nunber Pause between pages yes no Check printer message e fe A E L Check page length e increment prin out number Get data record l Print proper layout format Record Print record Print record totals if applicable Loop Print spacing between records if applicable Move to next search buffer pointer Check page length for formfeed Dispose of report format buffer and total buffers a ace standard entry screen Get data from last accessed search buffer node Print data record into entry screen qtE_ _ mii VI Code Design pa 53 Figure 15 System Structure Diagram continued Clear search buffer z Lists all fields available in record for search Input loop of chosen set of elements for the search r String Char begin or within search Byte Integer Real mininun naxinun d xxListMenu Input loop of search limitations j Date minimum amp maximun L L y r Get search index required for search criteria Find first record number in search FindData 4 Search loop adds data that meets criteria to search buffer Prints first record found or message of NONE FOUND L t Overlay Structure2. the program then uses the standard I 0 screen shown in Figure 2 and described below The following list contains the description and location of the standard items in the screen layout and their reserved areas Name Line Description of use Mode 1 Displays current mode chosen from the commandline menu Command means it is waiting for a command Add or Update are data entry modes Title 1 displays the title of the item selected from the main menu Name Manual Message Work area Commandline Files SecFile Found Cur RN Input Line i 23 25 23 23 SU Screen Design 31 Description of use always shows how to get the pop on manual or help screen displays messages such as error messages that tell what is wrong and what to do about it how to exit special instructions for the current situtation area for entry and data display commandline menu field level prompts number of records used in current file number of records used in current secondary or relational file such as a file containing sold items related to a primary file of invoice data number of records found in a search and contained in the current search buffer record number of record currently displayed on screen the actual physical location within the file prompt area for absolutely every operator input in these formats Byte H H HH Int H H HHHH Rea l HHH HH HHHHHEH
3. Approved for the Major Division Appro for the Graduate Council 11 IV VI VII VIII IX CONT ENT S Introduction eae ia a oa Sees pa Analysis a a s a a s Design a gt 5s a 8 Screen Design s a ss a Developer Interface a o Code Design a a a a e s The Library s a a 1 s s TeESting s m as te a AAA a Summar y s s s a a a s a s s Bibliography a aas aa a s 16 is 2 41 48 57 68 76 FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE FIGURE 11 12 13 14 15 Main Menu Screen a a 1 0 Screen Format Sample Sample Coding Menu Screen Sample Application Specific Help 4GL General Use Help Screen Entry Screen Code Screen do e Data Search Menu Screen Sample Data Search Screen Sample Sample Sample System System System Report Menu Screen Report Format Report Format Structure Diagram Structure Diagram continued Structure Diagram continued TABLE of FIGURES 38 32 33 34 35 36 36 37 38 3 40 46 31 52 53 I INTRODUCTION Overview This document contains a study of the first three critical phases of the software engineering process as it is applied to the project of creating a fourth generat
4. HH Max Length used for strings A C D F M R U texample of charact er input for command ines IV Screen Design 32 Figure 2 1 0 Screen Format MODE INBNANNANO title area J Fi Manual message line for errors and exits This is the working area used for data display and entry AE T AICA a AA INPUT PERNHHENHHHH HI Figure 3 below demonstrates a feature that an application developer may use for columnar type data entries It exemplifies an actual entry screen as may be defined by an application developer for the entry of an accounting transaction The example shows the screen after three transactions have been entered In this application all entries are made on the line directly under the column headings When the transaction is saved by pressing the Fi key a prompt line is inserted at this location pushing the previous transactions down thus keeping them on the screen as templates for further entries The design of the screen within the entry area lines 4 22 is under the control of the application developer On line 24 is a field level prompt describing the current field at which the cursor is located IV Screen Design pg 33 Figure 3 Sample Entry Screen MODE Add f ACCOUNTING Fi Manual Esc Command Line ENTRY F Del F18 Save F2 CODES BIT of Debit a CREDIT cea nernonnoesaanencrsacnss nal Debit Credit raha Acct Amount
5. Payable Drawing Capital Unexpired Insur i Unearned Fees PrePaid Expense Advanced Rev INCOME SUMMARY Received i Paid temporary proprietorship Decrease Equi ty td Equity Expense evenue l Inventory Begin Inventory End Purchases i Sales 1 ContraRevenue ContraPurchases i Sales Ret Al Pur R amp A Menu om aie pit paler tla Report Podn LES 47 SectILE ONE OS hare 2 am INPUT A C D F N R U Figure 7 46L General Use Help Screen MODE I ACCOUNTING J Fi Nanual Esc exit Manual Window space bar page for more F MANUAL J pu SPECIAL INPUT KEYS Hummm po oo HH BkSpc r Moves cursor to Ld i___ Tab NEXT input field Number Keys at Deletes character Top of Keyboard before cursor ONLY key used to adit WITH S or NumLock NUMERIC fields Ctrl pauses a scrolling screen Press Space Bar to continue ITH TAB moves cursor Shift re PREVIOUS input field as Deletes character ll above cursor in Alt text input field Del Ly Lo Menu Add ate lali rro Report P FILES aA a Fm INPUT A C D F M R U IV Screen Design 37 Data Searches From the commandline the operator may select F for Find to initiate a data search Figure 8 shows an example of a data search menu for a Chart of Accounts application Every possible field is listed and the operator may select one or all of the fields to search by If a st
6. 5 A duplicate key flag yes no Output Report Definitions Output formats for reports use the file field and index definitions entered as parameters by the application developer to create the proper data format to pass to the report routine The report formats are contained in a file called Rep Def PAS It is initialized with a table of 1 Report name 2 Related menu selection number 3 Report number V Developer Interface pg 45 The initialization table is followed by the report formats A format is initialized with The report menu number The report number Page length of the report document Body length of the report document The number of records per group The line spacing between groups A Wao I Items 5 and 6 allow for example for the grouping of data in sets of 5 lines and then double spacing between them for readability The actual body of the report is created in the following manner by the application developer Figure 12 gives an example of an accounting report format The first character per format line describes the use of the line The codes are Title line No data input into this line Divider line No data input Column heading No data input Primary file data line Footer line fields are totals or counters Page number line vnen 1 The symbol represents the location of a field within the report line A V Developer Int
7. Due to the limitation of Turbo Pascal version 3 the management of overlays is necessary in phase 1 Overlays were determined to be more efficient in this project than chaining due to the code design It is also possible for the application developer to create a batch file which automatically loads all compiled overlay modules into RAM disk therefore nearly giving the speed of an EXE program Four overlay files are used in this project Overlay Design Methodology The rules for using overlays can become quite involved when matched with the logic of a program A single overlay file can not contain modules which call any module within the same overlay code VI Code Design po 54 file including itself because they can not exist in memory concurrently For memory efficiency the modules should be of similar size and each overlay file should contain as many individual modules as possible The size of the largest module within an overlay code file is reserved in the main program memory for swapping in the called overlay modules To retain speed two or more overlay modules should not exist in a calling loop to prevent continuous trading of the modules into the memory overlay area for each loop One way to create an overlay system is to create a columnar table showing the calls or interfaces between only overlayed modules Global modules are not considered except for the fact that they must be declared before they are cal
8. for scrolling forward and backward sequentially as desired and allows for context sensitive help The standard user manual is pre installed however this manual is accessible to the application developer for editing Data Entry is standardized with I O screens defined by the application developer All data is entered within these screens and also displayed within them when in browse mode to page through a set of records in a search Data entry is also dependant upon file definitions defined by the application developer using parameter tables File sizes access codes indexing and field definitions are contained in these tables Data entry in a field uses the field definition to determine data type field length validity tests and its location within the record Each field has field level prompts displayed as the field is entered by the operator III Design pq 22 Phase 1 includes data types of string integer BCD real byte date and character Automatic sequential fields such as sequential invoice numbering and default fields are supported A key click option is available for keys pressed A lookup facility is built in for coded data fields as explained in the next section on the Coding System Validity tests are performed at the field level Coded fields are allowed which require entry of only preinstalled codes Numeric data is tested for minimum and maximum limits String data entry is not allowed beyo
9. life cycle from detailed design through coding testing and maintenance They focus on process format and documentation disciplines not information or project management A 4GL is actually a type of CASE but is more easily thought of as a subset of the CASE technology and also as the parent of the CASE In its broadest sense it is the the back end or lower CASE tool mentioned above As a response to many new needs fourth generation languages 4GLs are becoming more prevalent and are quickly replacing third generation languages 3GLs such as APA eee A AN OAR oN IN E ENA PE AREYE S AAN A eS I Introduction pq BASIC PASCAL COBOL FORTRAN etc A 3GL requires the application programmer to specifically use the language to tell the computer how to do every detail of each task Using a 4GL the programmer need only tell the 4GL program what to do This is due to the fact that a 4GL is an organized collection of pre written code which contains about 9 of all standard management code needed for all applications Just as an operating system is a collection of standard low level menial tasks that all users need such as device management character manipulation screen management etc the 46L contains a higher level collection of management macros that automate data file record field screen and report management tasks The application programmer no longer needs to re invent the wheel A
10. location of the cursor PROCEDURE WriteSt St Str255 WriteSt is a fast screen access equivalent to Write PROCEDURE WriteStLn St Str255 This is a fast screen access equivalent to WriteLn Window Handling Library PROCEDURE AddWindow WinNum Integer Writle Str8 AddWindow saves the current window contents and current cursor position in a buffer It can create a frame around the new window and then window inside the frame It locates the cursor at 1 1 in the new window and then sets window colors and clears the window screen WinNum is the number of an array of window definitions also set up as initialization parameters by the programmer PROCEDURE RemoveWindow NumToRemove Integer Removejlindow removes a given number of layers of windows resets the final window colors and relocates the cursor to the final windows last cursor position VII The Librar 59 Sound Library PROCEDURE Beep Beep merely beeps to get the operator s attention PROCEDURE Click Click creates a click sound and is called only by InKey below for each key pressed String Handling Library FUNCTION UpCaseStr S Str255 Str255 UpCaseStr changes string S to all upper case using inline code FUNCTION StrL Len Integer Character Char Str255 StrL returns a string of length Len filled with the given Character FUNCTION DelFrontSpc TLine Str255 Str255 DelFrontSpc returns a string
11. 3 editor can only handle 64K of code per source code file and for organization purposes the coding organization of the program includes the following separate protected code files Listed with the VI Code Design pq 49 file names are the contents of each Type Def Pas Library Pas FileMang Pas Pointers Pas Support Pas Controls Pas Menu Sys Pas Init Fin Pas all type declarations and a minimum of global variables a universal supporting library containing independent modules used by the entire 4GL program code for index keys file management pointer managemen t including queues double linked lists trees and buffers search menu print search data window get report option data report selection module data input module record managemen t related to data entry the 3 major controling modules which call the supporting modules in Support above EnterRecord FindData PrintReport menu system initialization and finalization modules Also included are two application specific files accessible to the application developer These are the files that contain the stubbed interface modules for the developer They are Speciall Pas UpDateAcct for accounting modules any data entry specific tests Special2 Pas any tests required for deletions specific report tests VI Code Design 306 eo es aaa System Diagrams The diagrams that follow present the high level logic and design
12. DOS 3 1 or higher and 326K of RAM A hard drive is recommended and mono CGA or EGA monitors are supported The application developer is required to use Turbo Pascal 3 x in the first phase of development and as soon as version 4 is shipped the second phase will use it as its base III Design pa 19 Initialization A parameter passed in with the call to execute the program declares to the program where the data files are located ie the drive and subdirectory specifications This allows the operator to keep sets of files within separate subdirectories Once loaded the initialization of the application program created by the 4GL includes an option for immediate update of files and the initialization of the date Exit from the program is possible even from this point A personalized logo screen designed by the application developer then appears to declare the program name and any copyrights and dates needed Pressing a key continues into the main menu screen Menus The main menu for the entire application created by the 4GL includes a list of installed database applications For example a simple menu may include Codes Chart of Accounts Transactions Audit Trail Whi nou we tl Each menu selected results in the use of the same screen layout described in more detail later When a menu item is selected the appropriate files are opened the I 0 111 Design pq 20 screen is create
13. alphanumeric data entered into numeric fields numeric data outside of the minimum and maximum limits characters not allowed in the field 2 the handling of the decimal point in real data fields 3 the cursor location especially in string input using both insert and overtype modes 4 the use and clarity of error messages VIII Testing DO 67 S the proper return of the input to the calling routine 6 the detection of special key combinations The first 3 stages can be tested simultaneously before merging them together Stage 4 Testing the merged modules with an actual application while attempting additions updates and deletions of every type must be completed before testing the report generation modules Stage 5 Report modules are now tested with standard screen layouts and then with various columnar layouts Record counts columnar totals and paging are tested extensively Stage 6 The final testing is a relational accounting application merged with inventory purchase orders and point of sale invoicing o IX SUMMARY The analysis and design presented here is now ready for another more detailed stage of design and then coding The 4GL is not a substitute for good analysis design and project management The major coding task has been completed for the application developer however a thorough analysis and design of the database iteself is the top p
14. and wild card searches Report formats allow for columnar formats page numbering column totals and counters Printer attributes such as bold and underline can be embedded in II Analysis pq 17 report formats User entered subtitles are also allowed Summar y In summary the functions that will be automated include 1 2 a menu system data entry display screen functions 1 0 screens color coding windowing data entry keyboard handling validity testing error handling data access searches report generation output printer control file management indices saving deleting reading data file internal data management buffers pointers system functions processing of data The top level design concentrates upon the user interface The lower level of design concentrates upon the mechanics and maintenance aspects This chapter will discuss the top level designing phase in terms of general requirements and of the functions to be automated Phased Development Development of this project is designed for two major phases The first phase uses Turbo Pascal 3 x BCD with the top priority features The second phase uses Turbo Pascal 4 and adds the more detailed features described in the following System Requirements Design begins with the declaration of the constraints This project is to be implemented on IBM PC XT ATs or compatibles XT ATs are preferrable with
15. with all front spaces deleted and is used for strings to be converted to numeric data because spaces will create a run time error FUNCTION LSet Len Integer Phrase Str255 Str255 5 LSet left justifies Phrase into a field of length Len FUNCTION Center Len Integer Phrase Str255 gt Str255 Center centers Phrase in a string of length Len Screen Handling Library PROCEDURE StatusLine Which Char Num Integer Message Str255 StatusLine handles all reserved message areas and color coding Any rearrangement of the screen would be done here VII The Librar 68 PROCEDURE ErrMessage VAR err Boolean Message Str255 ErrMessage calls Beep calls StatusLine 2 Messaget KEY TO CONTINUES calls InKey to create a pause and allow for an Esc and returns the previous contents of line 2 PROCEDURE ManualWindow This procedure is called any time an Fi is pressed It displays the manual in a pop on window and allows Paging through the on line manual PROCEDURE CommandLine VAR Command Char CSet CharSet Message Stri6 CommandLine calls ColorCodeLine to display a color coded commandline message on line 24 It then calls CharInput to input a char from CSet and sends Command character back to be used in a case to determine the next mode of operation Input Library PROCEDURE InKey VAR Special Boolean VAR Chari Char2 Char InKey loops until a ke
16. Acct fnount hoc Humbe Comments 98 01 01 1110 334 52 3128 334 52 B6 Beginning Bank Balance 88 01 12 6128 23 67 1110 23 67 CK 3241 Insurance Payment EE Enter Raa as 87 Y 5 zeros not necessar FILES 2 SecFILE OUND CurRN 3 GR INPUT Byte 12 On the fourth line above the name of the debit or credit is printed in the spaces when the respective account numbers are entered and found to be valid This is a result of two lines of specific code added by the application developer This presents an example of what special features can be accomplished with the 4GL Color Coding When the operator sees this screen on a color monitor the data entry area for the month is highlighted in yellow to indicate that this information is what is to be entered Yellow says do something The two bottom lines also verifiy what is to be entered IV Screen Design 34 Column headings are red The mode Fi Manual and status data on the bottom line are coded green Titles are brown Entry data that has already been entered is light cyan while the current data entry field is yellow Pop on Code Screen Figure 4 shows an example of a coding menu screen and Figure 5 shows an example of the screen after selecting a particular code to list This screen is available by pressing the F2 key while in the Add or Update mode Figure 4 Sample Coding Menu Screen MODE Add I ACCOINTING J Fi Manual Esc ex
17. E will also promote standard ization and support better and more accessible documentation resulting in lower maintenance costs In this way CASE will in principle redirect resources to the critical phases of requirements analysis and schematic desion Through extensive user surveys published in ComputerAided Software Engineering CASE BTR Business Technology Research of Wellesley Hills MAI determined that most users have been employing CASE tools for only the past 18 to 24 months las of March 1988 CASE tools break down into two segments design automation and programming Programming tools are primarily available on IBM mainframes at prices in excess of 100 000 according to Bayer David Bayer an industry analyst with Montgomery Securities San Francisco CA The trend however is to less expensive products that can run on micro and minicomputer workstation platforms He expects more sophisticategd programming tools to appear this year 1988 The project included herein is following the trend toward the micro market The CASE definition includes two distinct technologies Front end or upper case toals include the analysis and design aids Back end or lower case tools include application generators This project centers around the back end or lower case tools which are also labeled 4GLs or Fourth Generation Languages 4Gis These application generators assist the later phases of the software engineering
18. L I Introduction bd itself requires quite an involved programming project The ASCII programming team spent three and a half years work on their GhostWriter written in Turbo Pascal This document q y a 1 analyzes the type of product produced by this company II ANALYSIS A high level analysis at this point involves several directions The first step is to define the users and their respective needs The User Defining the needs or requirements of a software project also initially requires defining the user In order to avoid any confusion three terms are used consistently within this document 1 gt The software engineer who creates the 46GL 2 The application developer who uses the 4GL 33 The client end user or operator who uses the application created with the 4GL In this situation the application developer also known as a system developer is the user of the 4GL however while using the 4GL this developer produces applications for a variety of clients or end users This requires that the 4GL be written in such a manner as to allow for many different variations in database applications Therefore analyzing the needs of the application developer also involves analyzing the needs of as many client applications as possible The application developer becomes the middle man for the client the final application end user Thus two levels of
19. L can contain the characters or or sets bold attributes for printer output and sets highlighting for screen output sets underline on for printer output and sets low lighting for screen output turns off all attributes LineFeed is true to produce a linefeed Tk returns an incremented line count if output is to the printer and Prt gt 1 fue VII The Library pq 63 File Handling Library FUNCTION FileLen DF Datafile gt Integer FileLen returns the number of records contained in file DF It includes the number of records used and number deleted and ready for reuse FUNCTION UsedRecs DatF DataFile Integer UsedRecs returns the number of used records with current data in the file DatF PROCEDURE OpInterrupt This procedure checks for an operator interrupt using the END key It calls CommandLine to ask Do you wish to ABORT CY N This is used during reports FUNCTION IndexKey IndNum Integer RN Integer VR VariantRec IndexKey creates the index key for index number IndNum using the record number RN and the data record contained in VR a variant record used to pass all data records PROCEDURE NextKey VAR IndFile IndexFile VAR RN Integer VAR Key NextKey goes to the index file IndFile to get the record number RN of the next record in the index and returns the untyped Key for the next record PROCEDURE PrevKey VAR IndFile IndexFile VAR RN Integer VAR K
20. THE ANALYSIS AMD DESI GM OF a FOURTH GENERATION LANGUAGE A Thesis Presented to the Division of Mathematics and Physical Sciences EMPORIA STATE UNIVERSITY In Partial Fulfillment of the Requirements for the Degree Master of Science by Karen I Craft May 1988 AN ABSTRACT OF THE THESIS OF Karen I Craft for the Master of Science Degree in Mathematics presented on March 1988 The Analysis and Design of a Fourth Generation Language The enclosed thesis contains a study of the first three phases of the software engineering process as applied to the project of creating a fourth generation language C4GL gt Initially the 4GL is defined Three levels of users are also defined the software engineer who creates the 4GL the application developer who uses the language to develop a specific application program and the final end user who operates the application program created with the 4GL Included are schematic diagrams to show the logic flow of the language Sample screens are also included to show the results of using the language for an application The fourth generation language automates the code writing process with modules to handle menu systems data entry screen handling keyboard handling validity testing error handling data access and searches report generation printer control file and index management and internal data management of buffers pointers and system functions 463000 DP oct2 s
21. VELOPER INTERFACE The third priority of a 4GL must be the interface between the application developer and the 4GL itself The discussion in this chapter involves the communication between the 4GL and the application developer in terms of parameters which define I O screens output report formats and the database itself records and fields The major time spent by the application developer should now be in the area of the database analysis and design Once the design is established the installation of the parameters involves the following steps 1 Parameter tables define the base application for A the file data structure B the entry screens C the output or report formats 2 Specific non standard code is added using A the 4GL macro language described later B the Turbo Pascal language C inline and external code allowed through Turbo Pascal In phase 1 the implementation of the parameter tables is through tables set up in standard text files Phase 2 uses the 4GL itself to create these interface definition files The structure and content is the same with each method The phase 2 method allows for greater security and speed in reading the files and initializing the file definitions internally within the program V Developer Interface 42 Initialization The application developer must provide parameters for initialization of the system These include 1 the locatio
22. a similar approach is also needed for real time systems and many other areas The quest for efficient well engineered methods still goes on There has never been a program that is totally finished There is always another need that it might fulfill thus one revision after another Herein is only the beginning of a new 4GL adventure l urbo GhostWriter Taking the Time Out of Turbo Pascal This Month s MENU Vol 1 No 2 August 1987 pp 4 Paul Winsberg CASE Gettin the Bi Picture Database Programming amp Design March 1988 pp 54 Jan Snyders The CASE of the Artful Dodgers Infosystems March 1988 pp 28 he Reality of the Promise InfoSystems November 1986 pp 32 Kent Lawson Thinking About 4GLs Information Center January 1988 pp 28 brochures ASCII Automated Sof tware Concepts International Inc gt received January 1988 Pascal GhostWriter amounts to instant software Comdex Show Daily Vol 5 No 6 November 2 1987 pp 128 Siames R Hughes Moving Out of the Middle Ages Infosystems October 1986 pp 76
23. always be fixed later seems to be the attitude of the day Programming is costly enough when it is done correctly this haphazard rush to completion only adds to the costs both in maintaining the software a in producing truly useful applications In a software engineering project the greatest effort is expended in the later phases of the life cycle Coding testing and maintenance take far more time than analysis and schematic design In contrast decisions made early in the life cycle have the greatest impact on the quality and maintainability of the resulting software Studies have shown for example that errors detected during the requirements phase are corrected in far less time than errors detected during implementation or maintenance In other words the least effort is invested in the most important phases of the life cycle I Introduction pq 4 CASE A CASE product is any computer tool that assists any phase of the software engineering process The definition is quite liberal due to the fact that software engineering itself is a broad activity Any computer tool that assists in the process can legitimately claim the CASE label CASE tools perform analysis and design code generation testing and maintenance Few if any do all these things however gt CASE can partially automate the coding and testing phases This is the goal of application builders and code generation products CAS
24. analysis are considered the needs of the ERA A A o II Anal ysis pg 11 application developer and the needs of the developer s clients James Hughes explains a standard approach to the analysis process At project initiation a project team consisting of systems analysts and users assigned full time to the team must define the preliminary requirements of the system Traditionally at this point analysts would interview dozens of users to determine requirements This often produces a long list of wants and needs that are difficult to analyze and use for system development A better approach is to involve a few experienced users in the definition of preliminary requirements and major system externals such as menus data entry screens on line query displays and reports These system externals should then be incorporated into a horizontal prototype Users can review and rank the functions in the horizontal prototype to determine which functions should be automated Software Engineer and Application Developer Needs The software engineer the 46L developer and application developer user of the 4GL gt have much in common They are 4 a II Analysis 12 both developers for a client The software engineer creates general applications for the application developer and the application developer creates specific applications for the client end user As mentio
25. code files created by the 4GL developer are designed to handle 88 99 of all application needs These include automatic handling of the functions listed in the Standardizing Applications paragraph above Additional code added by the application developer is typically 1 5 of the total II Analysis pg 16 Client End User Needs Quite often the client end user is a novice with respect to computer operation ATI design is directed to the needs of the new computer user As mentioned earlier maintenance is the top priorty of the entire project but consistent user interface is the second priority Every move required from the operator is to be thoroughly prompted In more specific terms this first of all requires a standard screen layout in order to assure the operator that all prompts will be consistently seen in the same format throughout the entire program operation Color coding aids in prompting the user also Help screens are available at all times Data input is prompted at the field level with data type data limitations and field descriptions All data is checked for validity and any required or coded fields are tested before saving the record to the database Searches of the database allow for multiple searches for any limitations on any or all fields available in the file The first phase of development allows for searches of concurrent search criteria however the second phase allows for OR NOT XOR
26. d and the file and field definitions are initialized Command Line Once within a menu selection a commandline appears at the bottom of the screen Two forms are used The first allows adding and updating of records and the second allows only reading of data Menu Add Update Find Data Clear Report Pollp Pon gt Nenu Find Data Clear Report PgUp PgDn gt Phase 2 includes security password options which allow for read write access or read only access therefore determining which commandline the end user will see I O Screens Data entry and display for browsing through a search buffer screens are the same Standard I O screens contain the following the menu title the current mode of operation a message area for errors and how to exit a data entry area a commandline area a field level prompt area an input prompt for data entry limitations a status line including the number records in the current files the number of records in the search buffer the record number of the record currently being entered or viewed Ono ANA wM II Design ES 21 Help Screens Help screens are constantly available by pressing the Fi key Phase i help screens include user specific information such as accounting aids and a user manual displayed sequentially in a circular list as the space bar is pressed Phase 2 screens allow for going to specific pages in the on screen manual
27. d the data entry area line 8 in the example must be created File and Field Definitions The file structure of the database is the basis of all specific data input routines file and record management routines and output report routines The file and record definitions are created in table form in a text file called File Def PAS The file contains the following data pertaining to a specific file File security code read write read only Record size Number of fields per record Set of indices indexing the defined file The major index for the file aim wh l V Developer Interface f pg 44 It must be remembered that the 4GL does reserve menu B and file for the code library described earlier File Def PAS also contains a table of the following data pertaining to specific fields within a file Field data type Field name used in the search menu Field level input prompt An upper case flag for string data yes no Field length internally within the record Field offset internally within the record Field minimum and maximum acceptable values Character set possible for character data QnA Wd whe 1 The final table included in File Def PAS is another table containing the definition of the indexing system 1 The source file for the index data 2 The total number of fields used in the key 3 The set of ordered fields to create the key 4 The key size in bytes
28. earch If a report is requested and a search has not been executed then one is automatically requested from the operator A search menu is then listed as in Figure 18 below The operator has the option to see the report format Figure 11 before executing the report in order to be sure it is the correct one Following that the operator may opt to have the search criteria listed in the heading of the report to have page numbers and to send the report to the screen printer or both Figure 18 Sample Report Menu Screen MODE Report I CHART OF ACCOUNTSI Fi Manual EXIT Search Menu Esc aas REPORT MENU ena Chart of Accounts Account Balances Yearly Account Balances ist Quarter Account Balances 2nd Quarter 2 4 Account Balances 3rd Quarter oe Account Balances 4th Quarter 1 3 5 ccount Financial Report Account Balances Beginning Enter report number gt q _ _ ________z_ _PE9A ORO FILES 48 SecFILE FOUND 28 Curie INPUT int i 8 IV Screen Design pq 489 Sample Report Format CHART OF ACCOUNTS KEY to CONTINUE ACCOUNT BALANCES 15t QUARTER HHN aa a Balances January February March ist Quarter Figure 11 MODE Report Fi Manual SADA sd a o a aaia A A e are i n A A e SS E ROT SOIN Accti Account Nane NAANA listed ae A A aE I Page HiH b FILES 48 SecFILE FOUND 28 CurfW MN INPUT E 3 3 E Y DE
29. ed report he may opt to have the report format displayed before continuing This allows the operator to be sure he has the proper report Counters paging column totals and numeric grouping by groups of 5 for example are available directly through the formats created by the application developer To implement control breaks other than numeric grouping the application developer adds specific code The page length is set in the report format and is the key that automatically manages pagination and the creation of a title block at the top of each report One line in the report is required to contain fields from one common file Phase 2 allows for a more free form type report in which fields on the same line can be contained in different data files Phase 2 uses the 4GL itself to create the report formats and parameters and also allows a maximum width report of 132 characters A mathematical formula or a special logic procedure can be manually coded by the application developer E III Design pq 27 Printer Support Due to the fact that there is l little standardization for the many printers on the j market each printer requires its own set of driver codes for special attributes such as bold underline compressed 6 or 8 lines per inch italics and double wide Printers are supported by a parameter file containing these code numbers The file is created by the application developer and allows him to install code
30. eger VAR Bite Byte Bot Top Real UnderL NextLine Integer Prompt Str255 PROCEDURE Linelnput lt Ins TabOver Integer VAR TLine s Str255 Bot Top Real UnderL NextLine Integer Prompt Str255 PROCEDURE Datelnput Ins TabOver Integer VAR TDate Bytes Bot Top Real UnderL NextLine Integer Prompt Str255 PROCEDURE CharInput Ins TabOver Integer VAR TChar Char Bot Top Real UnderL NextLine Integer Prompt Str255 PROCEDURE RealInput lt Ins TabOver Integer VAR TReal Real Bot Top Real UnderL NextLine Integer Prompt Str255 VII The Librar o 62 EO eee Output Library PROCEDURE PrtStat PrtStat checks to see if the printer is turned on and select is on If either is off then it gives an error message and waits for the operator to input to continue or to exit PROCEDURE PrtPrint Prt Integer Format Str255 Prt is 1 for screen only output 2 for printer only output and 3 for both outputs If Prt is 2 or 3 then PrtStat is called Format is the message to be output with no linefeed PROCEDURE PrtPrintin Prt Integer Format Str255 This is identical to PrtPrint with a linefeed added PROCEDURE FormFeed This sends a formfeed to the printer if Prt is gt 1 PROCEDURE ColorCodeLine lt Prt s Integer L Str255 LineFeed Boolean VAR Ik Integer Prt is 1 for screen output only 2 for printer output only 3 for both outputs
31. erface pg 46 Figure 12 Sample Report Format T HHHH ACCOUNT BALANCES 4th QUARTER HHHH D C Acti Account Nane October November December Quarter Bal N A a e io dl ES MR Rs F AHH listed HAHHH HHHH HIHHH F P Page HiH MA Source Data M line Source Nun MNun FileSub Fids Source Field Array gt 3 1 6 2 3151617 21 2 1 4 86 151617 The lower source data part of the table above defines the field content of each input area for the fifth and seventh lines in the format The example defines the primary file as the source for the fields listed in the source field array The fifth line for example has 6 fields which are numbered 2 3 15 16 17 and 21 input into the format This works much like the FORM command in Turbo Pascal or like the PRINT USING in BASIC Field number 8 the first source field on the seventh line represents the record count at the bottom of each page of the report If the page numbering option is selected at the time of the report then the page number will be printed using the format line preceded by the P es in a Y Developer Interface pg 47 Specific Code A standard logic for IPO Cinput processing output is embedded into the system however it is impossible to foresee all uses for a program as the many versions on the market prove Therefore the use of unprotected stubbed procedures within the 4GL system allow for the application developer to further custom
32. ey 3 This is identical to NextKey above but gets the previous record PROCEDURE ClearKey VAR IndFile IndexFile ClearKey sets the index pointer to the beginning empty node of the index VII The Librar 64 PROCEDURE FindKey VAR IndFile IndexFile VAR RN Integer VAR Key FindKey must be preceded by a ClearKey command for IndFile It searches for the given index Key in IndFile It finds the first occurance of an exact match PROCEDURE SearchKey VAR IndFile IndexFile VAR RN Integer VAR Key SearchKey must be preceded by a ClearKey command for IndFile It searches for given index Key in IndFile For example if IndFile has keys of CATALYST CATAMOUNT etc and Key is CAT then the RN associated with CATALYST is returned and Key CATALYST It finds the first occurance of the first part of a key If none is found then returns a global flag OK as false PROCEDURE ManageFileSet DoWhat Char FSet FileSetType DoWhat is either 0 for open or C to close files FSet is the set of numbers of the files to be operated upon Indices are automatically updated and the existence of files and indices are tested if a file or index does not exist the operator is asked if the file should be created Miscellaneous Modules FUNCTION Yes Ins TabOver NextLine Integer Prompt Str255 Boolean Yes calls CharInput with character set of Y N and returns a boolean value o
33. f true if the character is Ys PROCEDURE ClrLine CirLine clears the current line where the cursor is located PROCEDURE IntDate VAR IDate Byte3 IndDate returns the system date in three bytes of information Cyear month day VII The Librar mm 69 PROCEDURE IntTime VAR ITime Byte3 IntTime returns the system time in three bytes FUNCTION Date Str8 Date returns the system data in string form C CC CC FUNCTION Time Str8 Time returns the system time in string form QG 0 All other procedures and functions are self managing and will not be called by the application programmer They are the kernel of the system and are called only by the the program itself Testing of the 4GL must be extensive because it is the basis of many applications To prevent compounding errors separate testing stages are as follows Stage 1 File management is tested as a separate module to guarantee that all data is saved retrieved and deleted properly Stage 2 The menuing system and screen handling are tested with stubbed calls to the file management routines This includes testing the windowing system It must be verified that all screens retain their consistency according to the design described earlier Stage 3 Input routines are tested separately before integrating them into the Data Entry system The major features to be tested include 1 the error handling for invalid entry of data
34. for browsing through the data on the screen paging to the previous or next record or to print out numerous reports Once the search has been III Design pq 25 used the search buffer can be cleared To see what search criteria have been used for the current search buffer the operator can enter D for data at the commandline A pop on window will display the list of criteria used for the search The count of records contained in the current search buffer will be displayed at the bottom of the screen Phase 2 will add the OR XOR NOT IF THEN ELSE and wildcard searches and also will allow for ascending or descending sorts according to any chosen combination of fields Search and replace features will be added in this phase An operator option is available to search for case sensitive data Ad hoc searches are allowed in this phase and commonly used searches are saved as standard macros Data Reports Report formats are initialized by the application developer In phase 1 these will be implemented using text files These formats will include field locations and field numbers Special printer options such as bold underlining and compressed print will be imbedded within the formats When requesting a report the end user is requested to initialize a search if none exists A numbered list of installed reports is 111 Design pq 26 displayed in menu fashion When the operator selects the desir
35. in a form similar to a Warnier Orr diagram Figure 13 contains the most general logic of the program Figures 14 and 15 continue with more detail for the Record Menu Keys section in the lower right corner of Figure 13 VI Code Design gt 31 Figure 13 System Structure Diagram Set screen Get data drive parameter where data will be located Initialize 5 global variables and flags E Initialize global postre for buffers files indices menus Read defaults and file definitions m _ currently in sequential data file Initial Up Screen ization Collect Record Definitions Retain original video mode set new default video mode Request inmediate upeate yes no Initalize menus file definitions buffers and printer codes Clear ring buffer pointers Re initiali ize 5 global flags Close open files to update disk directory Dispose of previous screen definition pointers Menu Main menu screen Input new menu selection Open new file set Create new entry screen and saves current work windows Initialize menu variables and pointers Control l Loop nitialize search record Initialize quit nap Read Only Nenu sFind Data Clear Report PgUp PgDn Conmandl i ne Read Wri te Nenu Find Data Clear Repor t PgUp PgDn Add Update Command Loop Tests for empty files and buffers Pagelp Key get prev record data print fields Case key of PageDn Key get next reco
36. ion language Initially it is necessary to provide some background information which defines the terms software engineering CASE Computer Aided Software Engineering and JGL Fourth Generation Language Understanding these terms will aid in better understanding the goals of the project Background Information Within the past few years the ever changing micro computer software market has presented many new problems to solve In the world of value added computer retailers VARS specific target markets have become the emphasis such as medical dental retailer inventory accounts receivable or general ledger applications to name a few Off the shelf software is too general for these specialized fields therefore custom software becomes a necessity With the recent flood of these market needs the software engineer is forced to develop more efficient methods to produce the volume of 1_ _Intreduc tion applications needed Tom Adams team leader at ASCII Automated Software Concepts International Inc and the designer of GhostWriter describes the changes required in the programming approach at ASCII We had to find a competitive and affordable way to do custom software We decided to develop a package that automated the code writing process Custom programmers find it necessary to increase productivity and coding efficiency to standardize their applications for maintenance efficiency and still retain versati
37. it Code Window space bar for aore 1 SOURCE DOCUMENTS 2 SUPPLIER CREDIT CODES 3 CUTOMER CREDIT TERNS 4 INVENTORY CATEGORY CODES 3 SALE CODES 6 SALESMEN 7 INSTALLERS Enter Code number desired FILES Sectiles FOUND Curf 36 INPUT Int 8 255 EE EERE SE EE SS ERE EW Ee TE ERE SRE OR Hips IV Screen Design pO 35 After selecting the code listing desired 1 for example a screen similar to Figure 5 is seen Figure 5 Sample Code Screen MODE Add ACCOUNTING J F1 Manual Esc exit Code Window ce bar for more CODES EERE EEEE CODE DESCRIPTION DELETE amn enmeno wee ee eeee Zee se e e O O o 1 SOURCE DOCUMENTS 1 CH Cash Transaction 1 CK Check Transaction 1 IN Invoice 117 Interest ZLZZZ 1 FILES Sectiles FOUND Curie 3 GH INPUT Int 8 255 Manual Hel p Screens The on line manual is available at any time by pressing the Fi key Below is an example of an application specific help screen and of a 4GL general help screen IV Screen Design pq 36 Figure 6 Application Specific Help Screen MODE t ACCOUNTING J Fi Manual Esc exit Manual Window space bar page for more FT MANUAL G s A ACCOUNTING EQUATION emma Transport in Sales Discts i Pur Disc Uncollect Accts LIABILITIES EQUITY Increase e gt Y Decrease Assets Decrease i Increase Decrease i Increase New Assets Accum Deprec Paid
38. ize the final application Turbo Pascal commands inline code external code and internal 4GL macros are available for the application developer to complete the specific code The following chapter describes the macro language in more detail and lists the major macro Jibrary procedures and functions This specific code should be the only part of the final application that would possibly require maintenance thus greatly reducing the cost in time and manpower for maintaining each application WI CODE DESIGN This chapter concentrates upon the design and organization of the actual 4GL code modules A more detailed level of design requires a data structure an organization of the code files and system diagrams 46L_ Data Structure The internal data structure of the 4GL must be well designed in order to be parameter driven compact enough for PCs and as unfettered with limitations as possible The major structures designed within the system are The use of the B tree indexing structure The use of pointers and linked lists The direct or absolute addressing of data The allowance for subscripted arrays of pointers to records for menus files fields indices and buffers bn l Dynamically created definition records are used to contain all current working data needed for the current menu item selected Organization of Code Files Due to the fact that the Turbo Pascal version
39. lays and managing data files Both the software engineer and the application developer have access to the use of inline and external code to speed up processing Memory efficiency can also be implemented using inline and external code Due to the fact that the constraints of the project include use of PC XT equipment it is necessary to keep the code as compact as possible The 4GL developer can compare the memory required by one algorithm over another in order to determine the memory efficiency Maintenance efficiency is included here as the top priority requirement It is not a truely measurable feature However all design for the software engineer and application developer must have an underlying purpose of II Analysis 14 being easily updateable as new needs surface This becomes a gray area An elaborate algorithm may be quite efficient time and memory wise but too difficult to maintain because of a lack of readability Readability is based upon the opinion of the programmers and dependant upon their expertise Readability and maintenance have top priority over speed and memory Standardizing applications is important in two major ways From the programming and maintenance point of view standardized algorithms prevent reinventing the wheel and save much development time From the application developer s point of view this is the major purpose for using the 4GL The application developer no longer needs to be co
40. led The major controlling modules are singled out In this case that includes the main module which calls Initialization Menu and Finalization The first and last are ignored since they are only called once at the beginning and the end of the program and therefore can be located in any of the overlay files conveniently The control loop logic is then the next area to consider The control loop calls EnterRecord PrintReport and FindData which are the three major operations of the entire program VI Code Design ts pda A column is then created for each overlay file in the design and each column contains the names of the modules in it To make it easier to design overlays the software engineer should use color coding with high lighter pens For example use green to high light the modules involved in the input of data into the program ie those used by EnterRecord One might use pink to mark all modules involved in the output of data from the program ie those used by PrintReport Yellow could be used to mark all modules involved in searches ie those used by FindData Any other modules might be marked with blue The next step is to draw color coded lines from one module to another to show what module calls another To complete the process each column must be checked to find the dominant module in other words the one that will be in memory the most The dominant module should be marked perhaps with red There may be one dominan
41. lity Continuity from one application to another keeps the maintenance and training effort to a minimum Software Engineering Software engineering is not just a matter of writing code The software engineering ife cycle involves a more or less standard sequence of phases At the outset of a software project a set of reguirements are gathered describing the objectives that the software must satisfy Next is an analysis of the requirements exposing important patterns and structures These are called the design specifications At this point software design begins Usually a schematic design phase precedes detailed design Upon completion of design code is written this is the implementation phase followed by testing and maintenance I Introduction 3 Software engineering therefore involves the following phases in the life cycle 1 Requirements gathering the objectives 2 Analysis exposing patterns and structures 3 Design schematic and then detailed design 4 Implementation actual coding 5 Testing verifying correctness 6 Maintenance correcting updating revising Advances in technology and techniques to improve the process have not kept up with the demand for new software or perhaps programmers have been too busy to learn them Whatever the cause many programmers have apparently decided to skip designing software in favor of just getting the job done It can
42. ll programs developed with the 46L then become standardized in these tasks and all standard or common tasks are handled the same from one application to the next A 4GL does the same thing for application programs that the operating system does for hardware only at a higher level The operating system standardizes the interface between the programmer operator and hardware devices and the 4GL standardizes the interface between the programmer operator and the application A truely I Introduction a pq 7 efficient 4GL will automate as many standard or normal tasks as possible All that is left for the application programmer to do is to add the non standard tasks specific to the application 4GLs have also been described as a continued evolution of languages a specialized language that has been designed to do a specific function as being able to do a task with roughly one tenth of the code needed in a 36L With 4GLs the precise instructions have been automated The language has been demystified 4GLs employ a dialogue between user and computer interacting to solve the user s problem The focus is on the task not on the computer Many levels of 4GLs exist from simpler 4GLs which allow an end user to create a simple database to powerful system house 4GLS used by sof tware engineers The difference between the two is the degree of flexibility and of the detail allowed in its use The simple 4GLs allow for o
43. n easily be re configured by the application developer with the simple reassignment of key constants Within the next four chapters are the more detailed aspects of the project This chapter concentrates upon the 1 0 screen designs used by the data entry routines and report browsing routines Standardized screens Standardized screens are not only a benefit to the end user but also to both the software engineer and the application developer End user interface is of utmost importance due to the fact that the majority of users are novices Being able to consistently find error and status messages and prompts in pre set locations aids greatly in the operation of the application program However the major advantage for the developers is the fact that all screen handling can be channeled through one screen formatting module Any desired changes in the screen layout are made in that one module Figure 1 is an example of a main menu screen from an application using the 4GL 1 IV Screen Design po 38 FIGURE 1 Main Menu Screen MODE Command Fi Manual MAIN MENU EXIT Program Esc Rewowoooo Nwm saooaqoawmxXn x woaaes_ _osos gt CODES CHART OF ACCTS ACCOUNTING AUDIT TRAIL SUPPLIERS CUSTONERS INVENT SALES Select A from above gt _ wl On OF Es OG PI Ak C 0 0 40 00 40 T wa FILES SecFILE FOUND Cur R MA INPUT Int 8 7 1 0 Screen When a main menu item is selected
44. n of the data files 2 The computer type PC XT AT gt 3 video mode 4 the filler character for entry areas 5 the client end user name 6 the program name 7 the logo screen with copyright and date 8 the option to have the click sound for keys a table of the main menu selections and their related files The menu title is used in the main menu and when a selection is made it is used in the title area of the entry screen The related files are automatically opened managed and closed during the use of that menu item I O Screen Definitions Screen definitions start with the definition of the window environment This includes 1 The related file number 2 The upper left corner location 3 The lower right corner location 4 Background color 3 Foreground color 6 The window frame type number The title color Y Developer Interface pq 43 Screen definitions include a table of the following data per source field The source file number The entry order number 3 for 3rd field entered in the input sequence Field location on the global screen Field number within the data file Location of the lower right corner for a windowed field as for a multiple line comment field Cn amp w ho The final step in defining a screen is the actual contents of the working or data entry area of the screen such as the entry screen in Figure 3 The column headings an
45. ncerned with how the application handles menus input keyboard handling validity testing and error handling output and printer control serein functions calor coding and windowing search routines buffers pointers system functions or even the processing of data indices and file management These are totally in the control of the 46GL The application developer then is concerned with what the system must do for the special application and not how it does it 11 Analysis pq 15 Versatility is a quality that can really only be measured with time Due to the vast range of specific application requirements of client end users it is impossible to foresee and allow for all possible features that might be needed by the application developer After the major design requirements are defined a further requirement is to allow for direct application programmer code within the program to add the non standard features Standard code is code that is protected and not allowed to be changed by the application programmer The requirement of versatility is provided for with code files accessible to the application developer that contain stubbed procedures in which any unforeseen specific application requirements are coded by the application programmer Standard Pascal commands and an extended language set of 4GL macros described in more detail later are available to the application programmer as the specific code is added The standard
46. nd in a circular list for paging through The operator then returns to the data entry from whence he came Once a code is used as a reference in a coded data field that is saved to a file the code is flagged and will not be allowed to be deleted to guarantee that it can be referenced by the coded field later Ill Design pq 24 Data Searches A data search menu includes a numbered list of all the fields in the records involved with the current menu selection The end user has the option to select any or all numbers of the fields for which he wishes to request concurrent special criteria a logical AND search After selecting the proper fields the end user is prompted for the special search criteria String searches are case independent and allow for two search type options Begin End searches locate data matching and between a user input beginning string to an ending string Data is matched from the beginning of the data field It allows for a search such as all names beginning with a to m Within searches locate all data fields which contain the user input string within them Numeric and date fields allow the user to input minimum and maximum limits on the search Searches involving an indexed field will be implemented using B tree indexing and other searches will be sequentially implemented Data search records are saved in a circular linked list called a search buffer The search buffer can be used
47. nd its maximum length limit Date entries are also tested for valid dates When an entry is executed using the Fi key the record is tested for the existence of required fields If the record is acceptible it is recorded and any updates to related files are also updated at that time such as updates to chart of account totals when a transaction is entered Phase 2 adds data types for telephone numbers zip codes social security numbers time and short dates tmm dd gt IlI Design pq 23 Coding System Due to the fact that it is storage efficient to use codes for some data fields a standard for all applications is a built in coding system Menu is reserved for Codes This menu selection allows the initialization of a coding library which contains lists of available codes used in the data entry of the entire program All coded fields used throughout the program reference this code library to test the validity of the data entry for that field Therefore all codes must be entered in the coding library before they will be accepted as valid data in the coded data fields No duplicates are allowed An example would be codes for source documents in a transaction such as CK for check or IN for an invoice These codes are indexed and quickly accessible at any time during data entry adding or updating by pressing the F2 key A pop on window lists the installed codes and their descriptions in alphabetical order a
48. ned in the introduction several quality requirements include increased product ivity code efficiency maintenance efficiency standard ized applications and versatility Further clarification is now needed Increased productivity involves the production of an application in less time than with previous methods This is easily measureable by keeping time logs on all projects however one must remember that not all projects are created equal Maintenance includes updating the system for changing needs correcting errors and adding new capabilities In most organizations it is estimated that 76 of the programming is dedicated to maintaining existing systems With 4GLs 76 of the time is spent on original coding and 36 on maintenance A ratio of 86 26 is the minimum acceptable goal of this project with the ultimate goal of a 95 S ratio The application developer is required to provide parameters to the 4GL to define the data file II Analysis pq 13 structure entry screens and report formats In other words the majority of the time for using the 4GL is spent in designing the application database as is necessary in any application however little additional time is needed beyond that stage Efficiency involves three major areas of concern speed memory and maintenance efficient code Speed efficiency can be measured with timing tests The 4GL developer must consider disk access time when using over
49. nly very basic standard functions while the powerful 4GLs allow the versatility of adding the unusual nonstandard functions when needed using the host language and the extended macro language of the 4GL itself This study considers the later the powerful system house 4GL I Introduction 0 8 ASCII the producers of GhostWriter define their product as 1 an automated code writing process 2 an application generator 3 an application development system and 4 a CASE Computer Aided Software Engineering product for program development The engineering approach contained herein echoes these four definitions and considers the 4GL as an extension of the Pascal language with the creation of macro procedures and functions for system house use to create relational database management applications Summary In summary this document contains the study of the first three critical phases of the software engineering process the requirements analysis and design phases for a fourth generation language Briefly this involves a subset of the CASE technology called the application generator technology also called back end or lower CASE It can also be described as an automatic code generator with screen report creation dictionary definitions data base management procedural language and functional integration as described in The James Martin Productivity Series The creation of a fourth generation language 4G
50. rd data print fields Alt Pagel Keys print prev sub pg within record ees ee pa Alt cone Keys print next sub pg within record ee call ax EnterRecord U call EnterRecord A Record Report call 2 PrintReport Menu Key 9 Clear search buffer s Find data PP we ei Window whole screen Finali Clear screen zation Video set to original video mode Be sure all pointers are nil and files closed 9 represents exclusive or or XOR logic a continued in more detail on following pages VI Code Design 32 Figure Enter Record PrintReport 14 System Structure Diagram continued Clear record buffer IF add Print entry screen Print new record number Initialize record variables Set current entry field location field length and offset Set input window if needed for large text fields Locate cursor Save entry field screen Initialize field variables Field Loop Print immediate input prosp da td routine according to type until get valid answer PutDatalntoRecord if no quit flag Goto next entry field ES SS SS a m m o o 3 re ee A 4 F18 P Save if PostOK ie if correct data then Savedata F9 Archive not currently installed Case of ce F7 Delete if deleteable then ask again print next record ey F2 A Codes pop on window Enter Tab go to next field in record Shift Tab go to prev field in record
51. ring field is selected the operator has the option to select a Begin End or Within search as described earlier If a numeric or date field is selected the operator is prompted to enter the minimum and maximum desired in the search Figure 8 Data Search Menu Screen MODE Search ICHART OF ACCOUNTS Fi Manual EXIT Search Menu Esc ase SEARCH MENU eee Comp mie 2 NoDelete Acc thun amp Acct Nane 5 Descript amp Begin Ba 7 Jan Total amp Feb Total 9 Mar Total 16 Apr Total 11 Ma oF tal 12 Jun Total 13 Jan Total 14 Aug Total 1 Sep Total 16 act Total 17 Nov Total 18 Dec Total 19 istOtTotal 20 2ndQtTotal 21 3rdOtTotal 22 4th tTotal Enter of items to be searched _ __ Q_ _ _ EEE FILES 48 SecFILE FOUND CurRN 42 INPUT 8 22 IV Screen Design pg 38 Search Data Window The operator may request a listing of the search criteria used to collect the current search buffer just in case one forgot by pressing D in the commandline A pop on search criteria screen appears listing all limits of the search as in Figure below Figure Sample Data Search Screen MODE Command CHART OF ACCOUNTS Fi Manual Esc exit from Window t SEARCH ITEM FROM i begin srch TO 3 Acct Num 2008 497 4 Acct Nane aF FILES Secfile FOUND CurRN 3 BM INPUT A C D F M R U IV Screen Design pq 3 Data Reports A report may be initiated after a s
52. riority before using the 4GL It will be only as good as the database design itself The 4GL has simplified the major functions that have now been automated The wheel has been invented and the six spokes are the following management routines 1 Menus and command ines 2 Screen management 3 Data entry management 4 Data search management 5 Report generation o I File and record management The 4GL now contains from 88 98 of the code needed for a relational database application With the modular design presented herein the application can be expanded to IX Summary mma 67 include more functions by 1 specific code added by the application developer or 2 by additional modules or expanded current modules by the 4GL developer These can both be done without disturbing the structure of the data files themselves Therefore the primary goal of maintenance efficiency has been maintained The secondary goal of consistent user interface has also been maintained with the above management routines Any additional management capabilities will still be implemented through the existing structure for screen management data entry management etc The acceptance of 4GLs has grown rapidly within the past few years It is however only the beginning Even more advancements must be developed to keep up with the never ending specialized needs of both today and tomorrow Database management has led the way but
53. s based Within this chapter is a list of the major library modules External Call Library PROCEDURE FrameWin UL UR LL LR Hor Ver Char FrameWin creates a frame around the current window using the given characters passed into it PROCEDURE GetScrn X Y NumChars Integer VAR ChArray ChArray is an untyped variable used to pass in a variable sized array of pixel data GetScrn gets the pixel data from the screen starting at position X Y which are global coordinates PROCEDURE PutScrn X Y NumChars Integer VAR ChArray ChArray is an untyped variable used to pass in a varing sized array of pixel data PutScrn puts the pixel data onto the screen starting at position X Y which are global coordinates FUNCTION GetVideoMode Integer GetVideoMode retrieves the current video mode from DOS PROCEDURE GotoxYAbs X Y Integer GotoxYAbs goes to the global coordinate position of X Y regardless of the current window VII The Librar e 58 PROCEDURE InitVideo Mode Integer InitVideo initializes the video mode to Mode which can be 6 7 Standard settings are 7 for 8 x25 text and 3 for 88x25 color text PROCEDURE SetCursorSize StartLine EndLine Integer This procedure sets the cursor size like the BASIC Locate statement FUNCTION Wherex bs Integer WherexXAbs returns the current global screen column location of the cursor FUNCTION WhereYAbs Integer WhereYAbs returns the current global screen row
54. s for for any or all printer interfaces for which he has codes File Management File management will be implemented with a B tree and indexing system Parameters will be supplied by the application developer to define files and their respective fields Restructuring of files is not allowed however a transfer from one file to another can be made A re indexing utility re indexes files that have been corrupted It uses the file field and index definitions to restructure indices after renaming the old indices to have as a backup until the process has been verified The operator then has the option to delete the old indices User Interface User interface is well served by pii Design pq 28 the several requirements previously mentioned standardized screens a pop on code window a pop on q manual or help window and constant prompting at the field level The user will know that he is expected to enter data when the color yellow or reverse video on monochrome monitors appears on the screen Even character input will be prompted by listing all possible characters allowed in the input Error messages must be preceded by a beep to signal the user to look in a pre determined message area At all times the user will have a message explaining how to exit the current situation The use of keys will be consistent throughout the application for the operator Standard key combinations are pre installed however these ca
55. t module in each column for EnterReport one for FindData and one for PrintReport However there should not be more than one per each of the three major controlling modules If there is any problem in deciding between several modules then perhaps a redesign should be considered VI Code Design pq S By looking for the dominant module in each overlay file the speed factor can also be considered An overlay may be more efficient if it is broken down into more overlays if very many of its modules are called frequently or are contained in loops that conflict In the diagram that follows the indicates the dominant module Overlay Overlay 2 Overlay 3 Overlay 4 NM Menu Managef ileSet Codeldindow InputData MenudEntry0K 4 MenviEntry0K H gt Entry0K Menv2Entry0K 4 H EnterRecord Delete0K MenuBPost0K 4 MenuiPost0K H gt Postik Menu2Post0K 4 Menu ScrDef 5 MenuiScrdef H gt CreateEntryScreen Menu Menu2ScrDef 4 Pointer library Key library xxListNenu PrintSearchData _ _ ____________ __ FndData SetUp GetReportData ReportSelection 4 cd die EEA WI I THE LIBRARY The master support facility for the modules contained in the system diagram is the protected code library of universally used procedures and functions which create a pseudo language or macro language from which everything else i
56. y is pressed If the click flag is true then it also calls click when a key is pressed and returns the key that was pressed as 2 characters The Special boolean is a flag that is true if the key pressed is a 2 code key InKey is implemented with an MsDos call PROCEDURE ReadStr VAR TStr str255 LMax Integer which Char SpecialWindow Boolean VAR BackX BackY Integer Absolutely all user input is entered through ReadStr in string form ReadStr locates the cursor tests for actual character input and special keys and key combinations VIT The Library pq l PROCEDURE IntInput Ins TabOver Integer VAR IntNum Integer Bot Top Real UnderL NextLine Integer Prompt Str255 Ins is for a no insert option any other number tells the program to insert a line at the input location TabUOver is the column position of the prompt message IntNum is the integer to be input if an original value is passed in then that value is displayed in the input area Bot and Top are minimum and maximum values allowed UnderL is the length of the underline prompt in other words the maximum length of the input area or maximum number of characters allowed to be entered NextLine is to flag for no linefeed carriage return and any other number sends the cursor to the next line Prompt is an input message preceding the input area The following are similar and related to IntInput PROCEDURE Bytelnput Ins TabOver Int
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