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EJB Server User`s Guide

1. seer 55 How EJB Server transactions Work cceesseeseeeeereeeeneeteaes 56 Benefits of using EJB Server transactions c eee 56 Defining transactional semantics 57 Example n sdi ie ave belie beaten ade 63 Dynamic enlistment in Bean managed transactions 64 OTS XA transaction MOdEl eee cece eeneeeeeeeeeeeeeeeeeeteneeeeaeeeeneeenaes 66 Working with EJB Packages and Components 000 69 Packages and Enterprise JavaBean component 00 69 Importing Enterprise JavaBean ee eeceeeeeeeneeteneeeeeeeeeneeeeaes 71 Installing COMPONENTS eean e ede nectishegek aaaea a 74 Modifying COMPONENTS ee e na ae aa aae aaa e a t aiae Ea a Aaa 75 Configuring component properties eee eeeeeeseeeeeeeeeeeeeeeeeeees 75 General component properties 00 ee eeeeeeseeeeneeeeeeeeeeeeeees 76 Transactions tab component properties s 77 Instances tab component properties ee eeeeeeeeeeeeeeeees 78 Contents Resources tab component properties eeeeeeeeeeeereeeeeees 80 Persistence tab component properties ee eeeeeeeeeeeeeees 82 All Properties tabla icc costes orenian a aarte art oa aA 84 Generating stubs and skeletons cccseccceeeeeeeeeeeseeeeeeeeeeeees 86 Creating Enterprise JavaBeans 0 0 00 eee eeceeeneeeeneeeeneeeeneeeeeeeetes 87 Modifying PaCkaGeS 00 eee eeseeeeseeeeseeeeeeeeeeeeeeeneeeeaeeseae
2. Default name service When you call the empty constructor to create a new InitialContext EJB Server sets the Context INITIAL_CONTEXT_FACTORY system property and sets the EJB Server EJB name service as the default An EJB reference identifies the home of an enterprise Bean You can use the deployment descriptor to create a link between an EJB reference and an enterprise Bean contained within an EJB JAR file Deployment descriptor interfaces allow an application component to access an enterprise Bean s home interface using EJB references To locate an enterprise Bean s home interface declare an EJB reference in the deployment descriptor and use JNDI to look up the interface The referenced enterprise Bean must be in the ejb subcontext of the application component s environment You can declare an EJB reference in the deployment descriptor using the ejb ref element The data between the opening and closing ejb ref tags defines an ejb ref element This code sample defines an EJB reference to the Employee entity Bean lt ejb ref gt lt description gt Reference to the Employee entity Bean lt description gt lt ejb ref name gt ejb Employee lt ejb ref name gt lt ejb ref type gt Entity lt ejb ref type gt lt home gt com wooster empl EmployeeHome lt home gt lt remote gt com wooster empl Employee lt remote gt lt ejb ref gt An ejb ref element contains e description This is option
3. Q Session Beans Entity Beans Adaptive Server engines The stub and the skeleton allow EJB Server to appear to run locally on the client Every component instance has its own stub and skeleton created specifically for it The stub resides on the client machine and is connected over the network to the skeleton which resides on EJB Server The stub acts as a surrogate for the client transmitting requests to the skeleton The skeleton listens on an IIOP port for requests from the stub When the skeleton receives a request it determines which method is required and then invokes that method Using the Sybase high speed JDBC driver EJB Server sends the request to Adaptive Server If values are returned the skeleton sends them to the stub which returns them to the client application EJB Server provides efficient management of client sessions threads third tier database connections and transaction flow without requiring specialized knowledge on the part of the component developer As a consequence developers can focus on solving business problems instead of programming the application s infrastructure Developers use classes and interfaces from the javax ejb packages of the JavaSoft API to create and deploy components To implement a component the developer must define interfaces and classes About EJB Server Feature summary Remote interface defines the Bean s business methods and extends javax ejb
4. EJB Bean EJB server EJB Server holds the EJB container which provides the services required by the EJB component EJB client An EJB client usually provides the user interface logic on a client machine The EJB client makes calls to remote EJB components on a server and needs to know how to find the EJB server and how to interact with the EJB components An EJB component can act as a EJB client by calling methods in another EJB component An EJB client does not communicate directly with an EJB component The container provides proxy objects that implement the components home and remote interfaces The component s remote interface defines the business methods that can be called by the client The client calls the home interface methods to create and destroy proxies for the remote interface 32 CHAPTER 3 Enterprise JavaBeans Overview EJB container The EJB specification defines a container as the environment in which one or more EJB components execute The container provides the infrastructure required to run distributed components allowing client and component developers to focus on programming business logic and not system level code In EJB Server the container encapsulates e The client runtime and generated stub classes which allow clients to execute components on a remote server as if they were local objects e The naming service which allows clients to instantiate components by name and components t
5. Property Concurrency Description Enabling this option allows multiple method invocations to occur simultaneously Concurrent access can decrease the response time of client method invocations Enable this option for any component that is thread safe If this option is disabled EJB Server serializes all method calls to the component Concurrency applies to execution of all instances Concurrency option disabled If the Sharing and Bind Thread options are selected the Concurrency option is implicitly disabled Bind Object Applies to stateful session Beans only When this property is enabled an instance is bound to a client s proxy reference until the client destroys or releases the reference If you enable this option your component must be thread safe that is one instance must be able to execute on multiple threads concurrently A client may call the proxy from multiple threads or pass the proxy to another process or component consequently there is no guarantee that calls are serialized with Bind Object enabled Component instances are destroyed when the client instance reference times out the time out period is configured on the Instances tab see Instances tab component properties on page 78 Instances are not pooled Bind Object is most commonly used for storage components which are used to store a component s state information in a database See Persistence tab component properties
6. Specify field to column mapping properties 112 If the table s primary key maps to a single field in the implementation class which must be the same type as the component s primary key display the All Properties tab and configure the properties in the following table Table 8 1 Mapping database columns to a single field Property name Value mapField key The database column name For single column keys only com sybase jaguar The name of the component field that the key component key field maps to To map database fields to columns display the All Properties tab and define properties to map database columns to fields in the implementation class using the name value patterns listed in the table below Table 8 2 Mapping database columns to class fields For columns of this type Property name Value Key fields enter one mapField field key The database property for each key Where field is the name of the column name field field in the implementation class that this key column maps to CHAPTER 8 Managing Persistent Component State For columns of this type Property name Value Non key fields mapField field The database enter one property for where field is the name of the column name each field field that this key column maps to You can optionally append a SQL type name to column names in square brackets For example to specify the column type must be varbinary 1024 ent
7. The Database component palette includes icons for adding transaction and query objects to a form You create instances of the Transaction and Query classes by selecting them in the palette and dropping their icons onto a form CHAPTER 9 Developing Applications with PowerJ and EJB Server To display retrieved data you can use either data bound controls with the query object or the DataWindow JavaBeans component On the Standard component palette many of the visual controls such as check boxes text boxes and labels can be connected to a data source and column so that they display the data in the current row of a query object s result set You make the connection to the query on the Database page of the control s property sheet Coding application logic What you do Events Methods Classes You can add your application logic in event handlers methods or external classes In choosing where to add this code keep in mind that effective encapsulation will make your classes more reliable and reusable Don t try to accomplish everything in a single method At design time PowerJ makes it easy for you to write code that gets executed when events are triggered Power takes care of the infrastructure for events such as event sources and listeners You just write event handler code that you want to be run when the event occurs If you want to set up a new event handler in your code then your code must set up the event infra
8. eeeeeeeeeeeiesiesierrierresrrnerrnerrnerrnerresreeet 13 Transaction management eeeeseeeeesereerierrierrrerirerrrerrnerene 13 Thread safety features eeeeeeeeeeeeeeeereererrrerrrerrrerrrereneene 13 Result Set support sssesssessressreerreenrnesrneetnnennnennnennrennnennrennnenne 14 Permissions and roles s sssessseeseeeiessreerreernsennsennsrnnsrnnsennsenne 15 PowerJ OVerv W sesssessiessieesreerrseensennsrnnrrnnsransrnasransrnernecnneee 15 Getting Started A aie aee aaa rear a eile 17 Before you use EJB Server ssssseesiesrresrrserisernsrenstnnrrnnsrnerrnerrneee 17 Terminology and CONCEPTS ce eeeeeeeeeeeeeeeeeeeeeaeeeeneeeeeeeeeeneeeeaes 18 TO rminOlOGy AA e E E E ET ETT 18 CONCEPTS araa a aaa rn a a rara UA Ca a SACAS A RS AA ORASAN E RST uA 19 Developing an application 00 0 eee eeeeeeeeeeeeeneeeeneeteneeeeeeeeeee 19 The EJB Server runtime environment ec eeeeeeeeeeeeeeeeeeees 20 BaSIC TASKS E EE cvenvens ierausacevetets guste EE 21 Using the Adaptive Server plug in to Sybase Central 22 Enabling EJB Server ee eeeeceeseeessereresneeesneeeseeessenersenerees 23 Disabling EJB Server ee eeeeeeseesseeceseeseseeeeseeeesaeeseeeeeseeeees 24 Starting EJB Server automatically eee eeeeeeeseeeeeeeeee 25 Starting EJB Server independently 0 00 0 eee eeeeeeeeeeeeeeeeee 25 Contents PART 2 CHAPTER 3 CHAPTER 4 CHAPTER 5 CHAPTER 6 Shutting down EJB
9. If you selected CT LIB OCI 7 x or 8 x specify the database name Default String The string used to connect to the XA resource You cannot modify this string which is automatically built from the information that you entered in the previous tabs Open String In this optional field you can specify any valid open string options For example for a Sybase Client Library 11 0 XA resource you can enter L logfile where logfile is where you want to store log information Close String In this optional field you can specify a value used by the resource to close a connection See your XA resource documentation for more information about the Open Suffix and Close String syntax Chapter 10 Configuring EJB Server Configuring Listeners A listener is an EJB Server port that communicates to clients using various protocols Supported protocols are IOP TDS and HTTP This section describes the tasks required to configure listeners You can e Create a new listener e Modify listener settings Preconfigured listeners Listener failover EJB Server comes with preconfigured listeners for all protocols The default host for these listeners is specified at installation You can also modify port number settings for the preconfigured listeners For more information see Modifying an existing listener on page 164 If a server cannot retrieve listener information from the repository for an IIOP listener or if a
10. on page 82 for more information on storage components Bind Thread When this option is enabled component instances are bound to the creating thread Enable this option if the component uses thread local storage If the Bind Thread option is selected multiple instances may still run concurrently on separate threads To ensure that only one instance is active at a time make sure that the Concurrency option is not selected When Bind Thread is enabled instances are pooled if the Pooling option is enabled The thread is pooled with the instance in this case Pooling When this option is enabled component instances are always pooled after deactivation If you enable the Pooling option in the Adaptive Server plug in your component is always pooled and these methods are not called 79 Configuring component properties Property Sharing Description When this option is enabled a single shared instance of the component services all client requests A shared component can store data in instance variables However if the component s Concurrency option is also selected you must add code to synchronize access to instance variables Sharing setting overrides Pooling setting If you select both Sharing and Pooling Sharing takes precedence Stateless For EJB session Beans the Stateless option is set correctly when the component type is set and must not be changed Transient For EJB statef
11. Home interface The full path to the Java class file that contains the Bean s home interface Bean class name The full path to the Java class file that contains the Bean s implementation class Primary key class If defining an entity Bean enter the full path to the Java class file that contains the Bean s remote interface If defining a session Bean leave blank Click Next The Adaptive Server plug in displays the Component Properties dialog box The Component s type and Java classes have been filled in by the importer Specify values for the remaining properties before running the Bean Installing components 74 Your component must be installed in a package before it can be run by applications Components that have the same name but are installed in different packages are different components modifying or deleting one does not effect the other CHAPTER 6 Working with EJB Packages and Components You can create a new component and install it to a package as follows 1 2 3 6 Double click the Installed Packages folder to expand it Double click the package to which the component will be added Double click the Add new component icon In the Component Wizard dialog box select Define New Component and click Next Enter the component name in the Enter New Component Name dialog box and click Next The Summary Page window displays Verify the component name The new component appears in the package
12. PowerDesigner PowerDimensions PowerDynamo PowerJ PowerScript PowerSite PowerSocket Powersoft PowerStage PowerStudio PowerTips Powersoft Portfolio Powersoft Professional PowerWare Desktop PowerWare Enterprise ProcessAnalyst Report Workbench Report Execute Replication Agent Replication Driver Replication Server Replication Server Manager Replication Toolkit Resource Manager RW DisplayLib RW Library S Designor SDF Secure SQL Server Secure SQL Toolset Security Guardian SKILS smart partners smart parts smart script SQL Advantage SQL Anywhere SQL Anywhere Studio SQL Code Checker SQL Debug SQL Edit SQL Edit TPU SQL Everywhere SQL Modeler SQL Remote SQL Server SQL Server Manager SQL SMART SQL Toolset SQL Server CFT SQL Server DBM SQL Server SNMP SubAgent SQL Station SQLJ STEP SupportNow Sybase Central Sybase Client Server Interfaces Sybase Financial Server Sybase Gateways Sybase MPP Sybase SQL Desktop Sybase SQL Lifecycle Sybase SQL Workgroup Sybase User Workbench SybaseWare Syber Financial SyberAssist SyBooks System 10 System 11 System XI logo SystemTools Tabular Data Stream Transact SQL Translation Toolkit UNIBOM Unilib Uninull Unisep Unistring URK Runtime Kit for UniCode Viewer Visual Components VisualSpeller Visual Writer VQL WarehouseArchitect Warehouse Control Center Warehouse Studio Warehouse WORKS Watcom Watcom SQL Watcom SQL Server Web Deployment Kit Web PB Web SQL
13. Use the home interface for the called component For transactions to occur with the intended semantics you must perform intercomponent calls using the home interface Do not invoke another component s methods directly EJB Server provides transaction state primitives that methods can call to direct the outcome of the current transaction Each component model provides an interface containing methods for these primitives These methods end a component s participation in a transaction both cause the current instance to be deactivated e completeWork The component finished its work for the current transaction and should be deactivated when the method returns e rollbackWork The component cannot complete its work Doom the current transaction and deactivate the instance when the method returns These methods are used to maintain state after the method returns they delay deactivation of the component instance e continueWork Continue this component s participation in the current transaction after the method returns and allow the transaction to be committed if the component is deactivated If a method calls no transaction primitive this is the default behavior e disallowCommit Continue this component s participation in the current transaction after the method returns but roll back the transaction if the component is deactivated before calling another primitive besides disallowCommit These primitives can be used to query
14. WebSights WebViewer WorkGroup SQL Server XA Library XA Server and XP Server are trademarks of Sybase Inc 3 01 Unicode and the Unicode Logo are registered trademarks of Unicode Inc All other company and product names used herein may be trademarks or registered trademarks of their respective companies Use duplication or disclosure by the government is subject to the restrictions set forth in subparagraph c 1 ii of DFARS 52 227 7013 for the DOD and as set forth in FAR 52 227 19 a d for civilian agencies Sybase Inc 6475 Christie Avenue Emeryville CA 94608 Contents About This Book PART 1 CHAPTER 1 CHAPTER 2 Dempa aream earar mi ctuuieunase suudegevav wands eutwbedduavyuudghath ctivesceuersdacekccudsstuereauateucwuyens ix OVERVIEW About EJB Server sainan aien na ania iaaa iaaa iaaii 1 About EUB Servet eecceeecseeseeecseneceeneresneeesaeeseeeecsanerseneeeesaeeeneners 1 Foaturo Siei rire piian intoa pi apia enana anian aa iae eia ana ieas Eaa teta aia diet 5 The EJB Server execution engine eseeeceeereerrerrerrierrrernere 6 COMPONENT SUPPOST ee eeeeeeeeeeeeeeeeeeeeeeseeeaeeeeeeeaeeeaeeeaeeeaeeeatee 7 Network protocol SUpport eee eee eeeeeeeeeeteaeeteneeteeeeeteneeeeaes 8 Administration and development tools eeeeeeeeeeeeeeeeeeeee 9 Client session and component lifecycle managemert 10 Naming Servico Spei ee eat aeaaaee iaai inai niaaa daana Satt 12 Connection caching
15. and the EJB Server name server updates this information whenever it creates new bindings or unbinds existing ones Chapter 11 EJB Server Naming Services To use an external naming service specify the URL of the external server in the Naming Service properties of the designated EJB Server name server You must also provide a manager DN distinguished name and password that has exclusive access to all objects in the LDAP server database for EJB Server to be able to update the stored name context information JNDI support Java Naming and Directory Interface JNDI is a standard Java interface for accessing distributed objects and services by name It provides a portable unified interface for naming and directory services The JNDI specification is independent of any specific directory or naming service such as LDAP NDS DCE CDS or NIS The EJB Server JNDI implementation includes the JNDI service provider interface SPI which enables you to use a variety of custom directory and naming services EJB Server uses the SPI in conjunction with the CosNaming interface to provide component lookup capability Given a bound name the SPI locates the referenced package and component Once it locates the component the SPI works with the client stub interface to instantiate the component and return the requested object JNDI version level In EJB Servers the JNDI InitialContext object follows the JNDI 1 2 interface specification When you s
16. configure an EJB Server to be a name server or point to another EJB Server as its name server The Naming Service property sheet includes e The EJB Server s initial context e Whether or not the EJB Server is enabled as a name server e Ifthe server is not enabled as a name server the URL for the EJB Server acting as the name server e Heartbeat detection periodically verifies that name servers are either accepting client connections or have failed Chapter 11 EJB Server Naming Services e If you are using an LDAP server to provide persistent name storage the URL of the LDAP name server as well as the manager DN distinguished name for the LDAP server For complete information about setting the Naming Service properties for an EJB Server see Naming Service on page 148 Name binding password security You can establish password protection on the EJB Server naming service to allow name binding only from designated EJB Servers This prevents unauthorized applications from creating name bindings using an EJB Server name server To use the name binding password feature you must set the com sybase jaguar server CosNaming bindpassword property for the name server and each server participating in the naming service You set this property using the All Properties tab in the Server Properties window The default value is jaguar All servers participating in the password protected name service must have the s
17. instead of connecting to your finance component server at host badger using port 9000 you can specify the initial naming context for that server such as USA MyCompany FinanceServer Components are identified by specifying an initial server name context plus the package and component name For example USA MyCompany FinanceServer FinancePackage PayrollAdmin This layer of abstraction allows you to move a server to another host without affecting deployed client applications Naming does require that one EJB Server use a well known stable host and port This server acts as the name server for other servers that participate in your application and clients connect to that server to resolve name requests You have the option of using persistent or transient storage for the naming database For transient storage the EJB Server builds the name database in memory when it starts based on the contents of the EJB Server configuration repository Naming configuration for a multi server application is briefly summarized as follows CHAPTER 1 About EJB Server Client APIs for naming 1 Choose one EJB Server to act as name server for the application You can configure this server to store names in memory transient storage or to store names in a third party directory server persistent storage 2 Configure each of the remaining servers to connect to the designated EJB Server naming server to resolve names Each server will also update the na
18. s list of installed components Configure the settings as described in Configuring component properties on page 75 Modifying components To modify a component 1 Highlight the component you want to modify 2 From the File menu select one of the following options e Properties Displays the Component Properties window described in Configuring component properties on page 75 Make any modifications required and click OK e Delete Removes the component from the package Configuring component properties The Component Properties window allows you to configure the settings that EJB Server uses to load the component and invoke its methods Component properties are organized on the following tabs 75 Configuring component properties Tab Description General Defines basic information about the component including the supported IDL interfaces the component type and implementation details Transactions Defines the components transactional properties such as how the component participates in transactions and whether the component explicitly commits its work Instances Defines how instances of the component are managed including instance creation thread binding and client component bindings Resources Configures properties that govern the component s use of server and database resources Persistence Specifies the primary key type for EJB entity Beans All Properties Allows you to
19. 16 properties to control instance allocation 78 recycling of instances 54 refreshing 85 refreshing after modifying 10 stateful 54 stateful vs stateless 54 stateless 52 54 storage 116 supported types 7 transactional properties 58 77 typesof 7 concepts 19 concurrency component property 79 configuring listeners 163 connecting to the Adaptive Server 23 180 connection cache properties 155 156 Advanced 156 cache by name 156 connection cache sanity 156 description 155 General 155 JDBC 157 name 155 number of connections 156 servername 155 service name 156 connection caches creating 153 defining 46 installing 153 managing 153 modifying 154 removing 154 support for 13 connection caching 128 connection timeout configuring for EJB clients 103 container 33 conventions Java SQL syntax xiii Transact SQL syntax xiv create methods IDL design pattern for 89 creating listeners 164 curly braces in SQL statements xv custom class list configuring 85 93 D databases data access and EJB Server 134 PowerJ JDBC access 126 138 transaction management 132 transactions inJava 138 deactivation definition of 53 default packages 70 deleting EJB Server packages 75 94 listeners 164 deploying components EJBJAR 48 PowerJ 48 deploying packages 10 description component property 77 EJB Server package property 94 design application 44 developing EJB Server applications 41 developing clients 49 developme
20. Adaptive Server host 1 Highlight the Adaptive Server host 2 Select File Disconnect Enabling EJB Server The installation process enables the EJB Server option in Adaptive Server Later on you can enable or disable an EJB Server in either of two ways e From the Adaptive Server plug in to Sybase Central e From the command line using isq Enabling EJB Server is a dynamic process You do not need to restart Adaptive Server for it to take effect After you enable EJB Server select File Refresh All to display the Enterprise JavaBeans folder beneath the host Adaptive Server 23 Basic tasks h lt h lt To enable EJB Server from the Adaptive Server plug in 1 Highlight the Adaptive Server host for the EJB Server 2 Select File Configure 3 Select enable enterprise java beans from the alphabetical list of configuration parameters 4 Change the number in the Value column to 1 5 Click OK To enable EJB Server using isq 1 Log in to Adaptive Server using isql 2 Enter sp_configure enabl nterprise java beans 1 Disabling EJB Server 24 You can disable the EJB Server option in either of two ways e From the Adaptive Server plug in to Sybase Central e From the command line using isql Disabling EJB Server is a dynamic process You do not need to restart Adaptive Server for it to take effect After you disable EJB Server select File Refresh All to remove the Enterprise JavaBeans fol
21. Adaptive Server plug in and configure the following fields on the Persistence tab Persistence Choose Automatic Persistent State Primary Key Enter the name of the primary key type see Allowable primary key types on page 89 If you have imported an EJB entity Bean the primary key has been defined already Storage Component Enter or choose the name of the component that manages interaction with the database See Storage components on page 116 for more information Connection Cache Enter the name of a JDBC connection cache that connects to the database The cache must have by name access enabled and be installed on all servers where your component is installed 111 Persistence for entity Java Beans e Table If using mapped table fields enter map table Where table is the database table name If you are using binary storage simply enter the table name e Time Stamp When you are using mapped table fields the Time Stamp setting determines how the server uses optimistic concurrency control to prevent overlapping updates to the same column Specify Acolumnname The name of a column in the mapped table that serves as a timestamp By default EJB Server uses a 4 byte integer timestamp and explicitly increments the value with each update The timestamp column need not be mapped to the component s persistent state fields Other processes that update the mapped table must increment the timestamp with each update
22. All clients for EJB Server components must be Java clients The Java client Java applets do not require customer installation and simplify the task of providing upgrades The customer always downloads the most recent applet If you do not want the customer to wait for the Java classes to download from the EJB Server you can install the Java classes on the client machine or use Marimba Castanet to speed up the download time If the client application is large and requires many Java classes download time might be unacceptable In this case use a Java application that is installed locally on the client machine This approach is ideal for intranet customers or even regular Internet customers Although not as simple as providing upgrades with an applet Java applications are no more difficult to upgrade than conventional software In fact Marimba Castanet can be used to automatically upgrade the Java application across the Internet Java IDEs such as PowerJ offer visual interface builders that greatly simplify the implementation of the user interface In some situations you might want to implement different versions of a client for different users For example you may implement a Java applet version to allow new customers to connect over the Internet without installing a client program For established customers who use the application heavily you can implement a standalone client program that offers improved performance Client design issues
23. EJBObject Home interface defines the Bean s lifecycle methods and extends javax ejb EJBHome Bean class implements the Bean s business methods and extends javax ejb EnterpriseBean Primary key provides a pointer into the Adaptive Server database and must implement Serializable Necessary for entity Beans only Sybase provides a graphics based management tool the Adaptive Server plug in to Sybase Central for EJB Server developers and administrators From this graphical interface developers can deploy components and administrators can configure the server For detailed information about creating and implementing EJB clients and components see Chapter 6 Working with EJB Packages and Components For detailed information about configuring EJB Server see Chapter 2 Getting Started and Chapter 10 Configuring EJB Server EJB Server features include the following A scalable multithreaded platform independent execution engine Dispatch and stub proxy support for the EJB component model High speed communication through Adaptive Server shared memory Graphical administration with the Adaptive Server plug in to Sybase Central Easy integration with Sybase PowerJ development environment Transparent client session and component lifecycle management Connection caching to allow reuse of database connections Industry standard naming services to resolve components using logical names rather than server
24. Full Text Search Specialty Data Store User s Guide describes how to use the Full Text Search feature with Verity to search Adaptive Server Enterprise data Historical Server User s Guide describes how to use Historical Server to obtain performance information for SQL Server and Adaptive Server Monitor Server User s Guide describes how to use Monitor Server to obtain performance statistics from SQL Server and Adaptive Server Monitor Client Library Programmer s Guide describes how to write Monitor Client Library applications that access Adaptive Server performance data Use the Sybase Technical Library CD and the Technical Library Product Manuals Web site to learn more about your product Technical Library CD contains product manuals and technical documents and is included with your software The DynaText browser included on the Technical Library CD allows you to access technical information about your product in an easy to use format Refer to the Technical Library Installation Guide in your documentation package for instructions on installing and starting the Technical Library About This Book Sybase certifications on the Web Java syntax conventions e Technical Library Product Manuals Web site is an HTML version of the Technical Library CD that you can access using a standard Web browser In addition to product manuals you ll find links to the Technical Documents Web site formerly known as Tech Info
25. Getting Started describes basic concepts terminology and basic task information you need to use EJB Server Part 2 Information for Developers describes EJBs and presents information about using the Adaptive Server plug in for Sybase Central and PowerJ to create EJB clients and components Chapter 3 Enterprise JavaBeans Overview describes Enterprise JavaBeans components Chapter 4 Creating Component Based Applications describes the process of designing building and deploying applications with components executing in EJB Server Chapter 5 Understanding Transactions and Component Lifecycles explains the EJB Server component lifecycle and transaction processing models Chapter 6 Working with EJB Packages and Components provides instructions for creating deploying and modifying EJB components and packages Related documents e Chapter 7 Creating Enterprise JavaBean Clients describes how to implement EJB clients using the Sybase EJB client runtime e Chapter 8 Managing Persistent Component State describes how to manage persistence for Enterprise JavaBeans e Chapter 9 Developing Applications with PowerJ and EJB Server gives an overview of how to develop applications using PowerJ and EJB Server Part 3 Information for Administrators describes how to set up and manage the EJB Server It also describes the system procedures that support EJB Server e Chapte
26. Ifyou change the connectivity library setting cache references held by components become invalid Attempts to retrieve connections or query cache properties will cause errors In this case the component must retrieve a new cache handle e Ifyou change other properties such as user name password server name or the number of connections in a cache cache references remain valid but components may be affected by the changed settings For example if you change the server name connections retrieved after the cache has been refreshed will go to the server indicated by the new name Connection cache ping This feature allows you to test the cache configuration to verify that connections can be made using the supplied parameters To ping the connection must be installed in the server that the Adaptive Server plug in is connected to If you have just installed the cache or changed any settings refresh the cache before testing it To test the cache with Ping 1 Open the Installed Connection Cache folder under the EJB Server icon where the cache is installed Right click on the icon of the cache you want to ping Choose File Properties In the General tab of the Connection Cache Properties dialog click Ping a A N The Adaptive Server plug in reports whether the connection attempt succeeded If Ping fails check the message text for a description of the problem The server log file may contain additional information about the
27. In designing your client plan to optimize network performance by keeping traffic between the client and components on the server to a minimum To optimize network performance plan to e Cache property changes in client data structures e Validate field values on the client 47 Deploying the application Deploying the e Update only the rows and columns that have changed For example do not implement a client to update an entire table when only a few rows have changed e Group data changes into larger sets with fewer method calls application After you have tested and debugged the application on your test server it is time to deploy the component files to a production server and make the client application files available to the application users Follow these steps to deploy the application 1 Deploying components on page 48 2 Developing clients on page 49 Deploying components Using PowerJ Importing an EJB JAR 48 To deploy components you copy component definitions and implementation files to EJB Server There are two ways to do this e Using Power e Importing an EJB JAR If developing Java clients and components you can deploy your application to the EJB Server directly from the Power IDE To deploy components configure deployment options using the Run Deploy options menu item then deploy using the Run Deploy menu item See the PowerJ documentation or online help for more informatio
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29. an EJB Server name server to an LDAP server 1 On start up the EJB Server name server connects to the LDAP server using the URL specified in the EJB Server name server s Naming Service properties The EJB Server name server authenticates the connection to the LDAP server using the manager DN specified in the EJB Server name server s Naming Service properties The EJB Server name server attempts to retrieve any existing matching name contexts from the LDAP server If successful the EJB Server name server uses the existing name context information The EJB Server name server prepares the server object with the required attributes The EJB Server name server attempts to add the server object to the LDAP server If the object already exists the LDAP server updates the existing object with the current attributes The EJB Server server adds any new package component name context information or modifies the existing information if necessary Index Symbols comma in SQL statements xv curly braces in SQL statements xv parentheses in SQL statements xv square brackets in SQL statements xv A activation component definition of 53 Adaptive Server plug in 46 131 application objects managed in 10 capabilities 22 generating EJB stubs with 98 overview of 9 setup 22 starting 22 addresses network configuring 8 specifying in EJB clients 102 afconfig dat file 159 applets about 119 distributed appli
30. aspect of your application s business logic A package defines a boundary of trust within which components can easily communicate Each package acts as a unit of distribution grouping together application resources for ease of deployment and management A stub is a Java class stub generated by the Adaptive Server plug in for Sybase Central and acts as a proxy object for an EJB component A stub is compiled and linked with your Java applets or client application A stub communicates with EJB Server to instantiate and invoke a method on a component in the middle tier Stubs make a remote EJB component appear local to the client A skeleton acts as the interface between the EJB runtime environment and the user code that implements the method Skeletons are compiled and linked with each of the components and at runtime they enable EJB Server to locate and invoke an appropriate method CHAPTER 2 Getting Started Concepts e EJB Server transparently maintains a session between a client application and the EJB Server Unlike a typical HTTP scenario where a new connection is created for each request and response sessions allow a browser to maintain a connection with the server across a multiple request response cycle EJB Server implements distributed computing architecture In this model three sets of elements work together to give users access to data e Client side applet or application e EJB Server components e Adaptive Server data
31. associated EJB Server Verifying the status of EJB Server To determine if EJB Server is running use the sp_extengine system procedure Log in to Adaptive Server using isql and enter sp_extengine SYB_EJUB status where SYB_EJB is the logical name of the EJB Server 27 Basic tasks 28 PART 2 Information for Developers This part provides an overview of Enterprise JavaBeans EJBs and information about using the Adaptive Server plug in for Sybase Central and PowerJ to create EJB clients and components CHAPTER 3 Enterprise JavaBeans Overview EJB Server supports Enterprise JavaBean EJB 1 1 components For details on EJB architecture see the EJB 1 1 specifications from Sun Microsystems at http java sun com products ejb Topic Page About Enterprise JavaBean components 32 EJB support 38 31 About Enterprise JavaBean components About Enterprise JavaBean components The EJB technology defines a model for the development and deployment of reusable Java server components called EJB components An EJB component is a nonvisual server component with methods that typically provide business logic in distributed applications A remote client called an EJB client can invoke these methods which typically results in the updating of a database The EJB architecture looks like this EJB Server EJB Container EJB Home Interface EJB Client EJB Remote Interface
32. compilation feature is disabled Set the value to true the default to disable the JIT feature com sybase jaguar server jvm options Specifies initialization options for the Java Virtual Machine You can specify any option that is valid for the java command line Separate options with commas for example Dmy system prop rty 1l foo Dmy system property 2 bar com sybase jaguar server jvm verbose Specifies whether the Java class loader should write information about each class loaded to the server log The default is false which indicates that class loader logging is disabled com sybase jaguar server jvm verboseGC Specifies whether the Java garbage collector should write information about each that is destroyed to the server log The default is false which indicates that garbage collector logging is disabled com sybase jaguar server roleservice The name of a custom component that evaluates user s role membership to control access to components and HTTP URLs The default value is AseAuth DbAuth com sybase jaguar server services A list of components that run as service components in the server com sybase jaguar server timeout Specifies the default instance timeout for stateful components running in the server com sybase jaguar server tx_timeout Specifies the default transaction timeout for components running in the server See Configuring server stack size on page 151 for information about setting server stack si
33. component attribute 58 2 Specify the component s transaction attribute Each component has a transaction attribute that determines whether instances of the component participate in transactions Transactional component attribute on page 58 describes the attribute settings and their meanings 3 Code methods to call the EJB Server transaction state primitives Each method should call the appropriate transaction state primitive to reflect the state of the work that the component has contributed to the transaction Using transaction state primitives on page 61 describes the state primitives in detail 4 Specify a transaction timeout period if needed By default transactions are never timed out You can configure a finite timeout period in the Adaptive Server plug in See Transaction Timeout property on page 62 for more information All components installed in one EJB Server share the same transaction coordinator Choices for transaction coordinator include e Shared connection This pseudo coordinator is built into EJB Server In this model all components participating in a transaction share a single connection To use this model all of your application data must reside on one data server and all components that participate in a transaction must use a connection with the same user name and password e OTS XA transactions For NT or UNIX users this option complies with the Object Transaction Service OTS and X
34. expire If you are creating an entity Bean specify the primary key as follows a Define the primary key type as one of the Allowable primary key types on page 89 b Click on the Persistence tab and type the name of the IDL primary key type into the Primary Key field The Persistence field must be set to Component Class the default Leave all other fields besides Persistence and Primary Key blank Click OK to close the Component Properties dialog box The Adaptive Server plug in has created default home and remote interfaces named package componentHome and package component respectively where package is the Adaptive Server plug in package name and component is the component name Edit the home interface methods following the design patterns described in Defining home interface methods on page 89 Edit the remote interface methods See Defining remote interface methods on page 91 Note If portability to other EJB Servers is required use only in parameters in remote interface methods If creating an entity Bean with container managed persistence configure the persistence settings as described in Chapter 8 Managing Persistent Component State Optionally configure the transaction properties for each method in the home and remote interfaces or if all are the same configure the component s transaction properties Generate stubs and skeletons for the component as follows a Highlight the c
35. export and choose File Export EJB 1 1 JAR 2 Enter the path and file name for the new JAR file and click Next 3 The Adaptive Server plug in creates the JAR file displaying status messages in the Export wizard 95 Exporting packages to EJB JAR files 96 CHAPTER 7 Creating Enterprise JavaBean Contents Clients This chapter describes how to implement EJB clients For general information on implementing Enterprise JavaBeans and EJB clients please see the EJB Specification available for download from Sun Microsystems Web site at http java sun com products ejb docs html If your site uses PowerJ please see the PowerJ documentation for information on code generation wizards for EJB clients Topic Page Developing an EJB clet 97 Generating EJB stubs 98 Instantiating home interface proxies 100 Instantiating remote interface proxies 104 Calling remote interface methods 106 Managing transactions 106 Serializing and deserializing Bean proxies 107 Developing an EJB client Follow the steps in the table below to create an EJB client Step Action For more information 1 Generate EJB stubs See Generating EJB stubs on page 98 2 Add code to create the initial See Instantiating home interface naming context and instantiate the proxies on page 100 home interface proxies 3 Add code to instantiate remote See Instantiating remote interface interface proxies proxies
36. for the components and clients CHAPTER 4 Creating Component Based Applications Figure 4 1 EJB Server architecture Host As in client server applications the client contains the user interface Unlike client server applications however business logic such as stored procedures is separate from both the clients and the database Instead business logic resides in the second tier as components that analyze data perform computations or retrieve information from data sources and process it You design an EJB Server application by coding these tasks into an interface and into method prototypes A primary benefit of this model is that you can include pre built components in the EJB Server application If these components have been built outside EJB Server you can import them using the Adaptive Server plug in Importing components adds their interfaces and method prototypes to EJB Server The client and components are built from the same interface and method prototypes You can build the client and components concurrently as long as the client and component development teams notify each other if either of them changes the interface or method prototypes 43 Designing the application Designing the Plan for server infrastructure needs Define EJB Server packages 44 application In the design stage you plan the infrastructure for developing and deploying the application define the EJB Server components
37. in connection with a user name to connect to the database identified by the server entry Passwords are encrypted in the EJB Server configuration file The Adaptive Server plug in does not display passwords for existing caches If you need to change a password enter the new password and click OK Select the Advanced tab on the Connection Cache Properties window to set the cache options described in Table 10 4 Table 10 4 Advanced tab connection cache properties Description Select this option to allow retrieval of a database connection using the connection cache name instead of requiring a user name and password Comments Example By default a cache cannot be retrieved by its name You must be logged in as sa to update the cache s properties to allow the cache to be retrieved by name Cache by name is less secure than requiring a user name and password Enable connection sanity check Whether connections should be verified before releasing them into the cache Components may release a connection that is not ready for use by another component For example there may be unretrieved results on the connection Enabling this option causes EJB Server to test whether the connection is usable before replacing it in the cache Disabling the option increases performance but may complicate debugging Number of The number of connectionsin After a connection is released it is returned to the pool The Connections the
38. limited to one word which can Cache configuration contain letters numbers and underscores Names are case Name sensitive You cannot modify the name of an existing connection cache Description The description of the The description is a string of up to 255 characters for the connection cache section cache Server The URL appropriate foruse in For the Sybase shared memory JDBC driver use Name JDBC calls jdbc sybase shm null 0 where host name null and port 0 zero because the connection is made through shared memory and not through the network Driver name User Name Set the driver name and properties using the Driver tab on the General window Your choice for library type is e JDBC for connections using the Sybase shared memory JDBC driver The user name for this cache The names for each of the cache types are For NT platforms JDBC the Java class name for the driver class For example the Sybase jConnect 5 2 driver requires com sybase jdbc2 jdbc SybConnectionPoolDataSource e For UNIX platforms JDBC the Java class name for the driver class for example com sybase jdbc2 jdbc SybDriver The name used along with a password to connect to the database identified by the server entry 155 Managing connection caches Property Password Advanced Property Enable cache by name access Description The password for this cache Comments Example The password used
39. manually edit component property settings in the EJB Server configuration repository For advanced users General component properties 76 The General tab defines basic information about the component including the supported IDL interfaces the component type and implementation details These properties may have already been configured correctly by the import process The following table describes the window controls CHAPTER 6 Working with EJB Packages and Components Table 6 1 General component properties Property Description Notes Component Specifies the type of the EJB components must be Type component which can be implemented in accord with version EJB Stateless Session 1 1 of the Enterprise JavaBeans Bean A stateless session specification bean EJB component EJB Stateful Session Bean A stateful session Bean EJB component EJB Entity Bean An entity Bean EJB component Comment Specifies description of the Enter a comment that describes the component The description purpose of the component can be up to 255 characters Class The name of the class that implements the Bean in Java dot notation Transactions tab component properties The Transactions tab configures the component s transactional properties Chapter 5 Understanding Transactions and Component Lifecycles provides useful background for the transactional properties Transaction attribute values The transaction attribute
40. on page 104 4 Add code to call remote interface See Calling remote interface methods methods on page 106 97 Generating EJB stubs Step 5 Action For more information Optionally add code to control See transactions and serialize and deserialize instances e Managing transactions on page 106 e Serializing and deserializing Bean proxies on page 107 Generating EJB stubs Stub classes act as proxies for an instance of the EJB component You can generate EJB stubs for components that are implemented in any of the EJB Server supported component models 98 h lt To generate Java source files for stub classes 1 Highlight a component to generate stubs for all interfaces and types required by a component Select File Generate Stubs Skeletons The Generate Stubs amp Skeletons dialog box displays Select the Generate Stubs option and the Generate Java Stubs option Enter values in the Stubs fields as follows Java Version Choose Java 2 0 if any home interface has finder methods that return java util Collection Java Code Base Enter the top level directory path where generated files should be created The path must be valid It can include a drive and as many directories as you want You can use SYBASE SYBASE_EJB Windows NT or SYBASE SYBASE_EJB UNIX to specify subdirectories within the EJB Server installation directory for example SYBA
41. on start up 148 server log srv log file 148 server properties General 146 initial context 168 Log Trace 147 Naming Service 148 167 servers as managed in the Adaptive Server plug inr 10 configuring network addresses for 8 overview of 6 protocols supported by 8 services provided by 6 use during development and testing 44 service components definition of 6 services provided by EJB Server 6 session client management of 10 definition 19 session Bean EJB component type 33 stateful 33 stateless 34 session management 10 shared memory connections 152 sharing component property 80 shutting down EJB Server 26 skeleton definition 18 sp_extengine stored procedure 26 sp_serveroption stored procedure 25 square brackets in SQL statements xv srv log file serverlog 148 starting EJB Server 25 state primitives for transactions 61 stateful components definition of 54 stateful session Bean 33 stateless components creating 54 deactivation and instance pooling of 52 definition of 54 stateless session Bean 34 states in component lifecycle 52 storage components configuring 116 definition of 116 stored procedures sp_extengine 26 sp_serveroption 25 stub object definition of 8 stubs and proxy objects 18 compiling 99 explanation of 8 generating 86 Sybase Central Adaptive Server plug in for 9 explanation of 9 syntax conventions Java SQL xiii Transact SQL xiv System Administrator role 22 Index T terminology component ba
42. resource configured for a database the EJB Server connection manager returns CS_FAIL By default EJB Server uses the XA resource library for the JDBC connection com sybase jdbc2 jdbc SybXADataSource You can also use these shared libraries or DLLs to obtain an XA resource that is exported from the database connection libraries 160 Chapter 10 Configuring EJB Server Connection library Shared library DLL Sybase Client Library 11 0 libjxa so libjxa dll Oracle OCI 7 x libcIntsh so xa73 dll Oracle OCI 8 x libclntsh so xa80 dll To change the shared library or DLL edit the connection cache properties file SYBASEY SYBASE_EJB Repository ConnCache lt cache_name gt props For example to instruct EJB Server to use oraclient8 dll instead of xa80 dll for Oracle OCI 8 1 x add this line to the connection cache properties file com sybase jaguar conncache xadllname oraclient8 dll Note You must install XA resources in an EJB Server before components in that server can access the XA resources You must refresh XA resources or refresh the server using View Refresh All in the Adaptive Server plug in or restart the server before any changes to the list of installed XA resources or to XA resource properties take effect If a configured XA resource is not running or cannot be connected to the EJB Server cannot initialize Copy an uncorrupted version of the SYBASE SYBASE_EJB config afconfig dat file back into the
43. s interfaces and implementation class but have not created a deployment descriptor You will need to manually configure properties that would otherwise be read from the deployment descriptor afterwards Importing EJB class files Before importing class files Verify that the code base under which the class file is deployed is specified in the CLASSPATH environment variable as inherited by the Adaptive Server plug in process Create a package to contain the component if necessary Import EJB class files as follows 1 Specify the package in which to install the component as follows a Open the Installed EJB Packages folder b Double click the package to which the component will be added 2 Double click the Add new component icon in the right window 73 Installing components The Component wizard displays In the Type of Component window select Import an EJB Class File and click Next Enter the component name and EJB class and interface names as follows Component name The name of the component to be created in the Adaptive Server plug in for example FinanceBean Component type Choose one of the following to match your implementation Type Description StatelessSessionBean A stateless session Bean StatefulSessionBean A stateful session Bean EntityBean An entity Bean with Bean managed persistence Remote interface The full path to the Java class file that contains the Bean s remote interface
44. supports instance pooling is said to be a stateless component because the component s state is reset across the boundary of a transaction and activation Early deactivation and instance pooling promotes greater scalability by enabling an increasing number of clients to use a static number of instances An application design based on stateless components offers the greatest scalability Generic component lifecycle EJB Server components in any component model follow the state diagram illustrated in this figure Figure 5 1 States in the EJB Server component lifecycle New instance Destruction gt gt 7770 kie Activation Deactivation Active Invoke method Invocation complete In Method The state transitions are as follows CHAPTER 5 Understanding Transactions and Component Lifecycles New instance The EJB Server runtime allocates a new instance of the component The instance remains idle in the instance pool waiting for the first method invocation Activation Activation prepares a component instance for use by a client Once an instance is activated it is bound to one client and can service no other client until it has been deactivated If a component is transactional activation also indicates the beginning of the instance s participation in a transaction In method In response to a method invocation request from the client the EJB Server runtime calls the corresponding method in the component The
45. t have to worry about deployment to individual users The main disadvantage of the Web architecture is that an applet must be downloaded each time it is run and unless it is marked as trusted cannot provide full application services such as accessing other files running other programs or making native calls EJB Server as Web server EJB Server can fill the role of Web server using the HTTP protocol as well as provide support for IIOP connections that invoke the services of the EJB Server transaction server Creating a distributed The general procedure for using Power to create a distributed or Web Java or Web application application that uses EJB Server is 1 Decide what functionality will be encapsulated in an EJB Server component Typically the component implements business logic that analyzes data performs computations or retrieves and processes data from the database 2 In PowerJ write the code for the component In addition to implementing the component s business logic you may also call EJB Server methods to take advantage of transactions and other EJB Server performance features information about these features follows 3 In PowerJ or the Adaptive Server plug in to Sybase Central define connection caches to manage pools of connections to the remote databases that your component connects to 129 Building distributed and Web applications that use EJB Server 4 In PowerJ set the deployment options for your com
46. targets and files together into a single manageable package It lets you organize maintain and publish all the files of an application for an intranet or the Internet Similarly archive file targets ZIP JAR and CAB can be used to collect other targets and files into a single archive file Each target has its own folder this avoids naming conflicts when source files have the same name All work in Power is done within a workspace which is a collection of one or more targets Your workspace can include all the targets involved in the complete application PowerJ creates a workspace definition file for a workspace The file is a summary of the workspace and lists all the targets that belong to the workspace CHAPTER 9 Developing Applications with PowerJ and EJB Server The Workspace view displays the targets in the current workspace A target s Build Options property sheet lets you specify options for building the target Views Of x File Edit View Go Tools Window Help eo OEE eee Targets And Files My Workspace SLEJBClient1 AE My Workspace SLEJBClient ClientBean JDK 1 1 or later Classes a ClientBeanAll Java JAR E a ClientBean JDK 1 1 or later Classes 3 ClentBeandll Java JAR 5 SIEjbClient1 JDK 1 1 or later Application 3 SIEjbClient JDK 1 1 or later Application Workspace My Workspace SLEJBClient1 Intemationalization Classes Each Java fi
47. the EJB Server through a firewall that does not allow IIOP traffic to pass EJB Server s Java client ORB performs HTTP tunnelling automatically using the designated IIOP port No additional configuration or proxies are required When connecting the EJB Server client side ORB first tries to open an HOP connection to the specified address and port If the IIOP connection fails the ORB tries an HTTP tunnelled connection to the same address and port The default behavior is appropriate when some users connect through firewalls that require tunnelling and others do not the same application can serve both types If you know HTTP tunnelling is always required for a Java client you can set the ORBHittp property to cause the ORB to use HTTP tunnelling without trying plain IOP connections first Administration and development tools Development support Sybase Central is a common management framework for Sybase application and database servers EJB Server provides the Adaptive Server plug in to Sybase Central plug in for developers and administrators The Adaptive Server plug in provides graphical administration facilities for EJB Server including support for development and deployment You can use Sybase Power 3 6 with EJB Server Using this IDE tool you can develop deploy and debug EJB Server components entirely within the development environment You can also generate the proxies required for client application development For more infor
48. the Persistence tab of the Component Properties dialog box The type for a sequence of remote interface instances is componentList and a sequence of primary keys is componentKeys where component is the component name The IDL for your Enterprise Bean s remote interface must define a remove method and the business methods implemented by the Bean remove methods are called by clients to delete the database row associated with an entity Bean and to release a reference to a session Bean instance remove methods have the following signature void remove raises CtsComponents RemoveException You can define business methods using a text editor The procedure is the same as for any other IDL interface Note If portability to other EJB Servers is required use only in parameters in remote interface methods To configure EJB 1 1 role references 1 Ifnecessary define new Adaptive Server roles to be used by callers of the component You can create roles in the Adaptive Server plug in in the Roles folder under the Adaptive Server icon Adaptive Server and EJB Server share roles 2 Verify that J2EE roles are mapped to Adaptive Server roles in the properties of the package where the component is installed check the Role Mappings tab in the Package Properties window see Configuring package properties on page 94 You must map a J2EE role name for each role to be used in role references 91 Creating Enterpr
49. the client Sending results row by row Connection caching How it works 134 Java components send result sets to the client using the interfaces in the com sybase jaguar sql package e Methods in the JServerResultSetMetaData interface define the format of rows in a result set e Methods in the JServerResultSet interface define column values for rows in a result set and send the rows to the client You don t have to implement these interfaces The jaguar server JContext class contains static methods for obtaining objects that implement these interfaces To send database data to the client e Get the data by sending a query to the remote server Use java sql Statement or one of its extensions The appropriate method depends on the query you are making e Convert the results of the query to TabularResults ResultSet You can also send the result set row by row by building another ResultSet object that contains a subset of the original query Methods in the metadata and resultset interfaces let you specify the columns and data in the result set A connection cache contains a pool of preallocated connections that components can use repeatedly as needed to communicate with a database server using a common user name and password Connection caching provides CHAPTER 9 Developing Applications with PowerJ and EJB Server Java Connection Manager classes e Improved performance through reuse of connections The EJB Server conne
50. the component interfaces and the EJB Server packages that contain the components At the end of this phase you will have packages and components defined in the Adaptive Server plug in Follow these steps to design the application 1 Plan for server infrastructure needs on page 44 2 Define EJB Server packages on page 44 3 Define components on page 45 4 Define connection caches on page 46 For an enterprise application implemented by several developers you may need to create several EJB Servers to increase developer productivity For example you might want dedicated servers for each of the following Component development Servers to test components that are under development or revision A typical configuration uses one server per developer running on the developer s personal workstation e Client testing Quality Assurance QA Client developers require a server with a stable installation of the application components to be used by client developers to test their programs During the early development phase you can deploy stubbed components to this server to allow testing of client connectivity and basic method execution A stubbed component has empty method implementations For most component models the EJB Server generates source for a stubbed implementation when you generate the component skeleton e Production You will need to install EJB Server on the host machine for the live version of the applic
51. wizard displays 3 Enter a name for the new server Server names must be one word and can be up to 30 characters long 4 Enter a port number for the new server The default is 9000 5 Select Finish 6 Install AseAuth from the Repository See Installing a package in the Adaptive Server plug in on page 72 for how to install a package 7 Set these property values on the All Properties tab of the EJB Server properties window for AseAuth e com sybase jaguar server authservice AseAuth DbAuth e com sybase jaguar server dbsecurityurl jdbc sybase shm null 0 e com sybase jaguar server dbsecuritydriver com sybase jdbc2 jdbc SybDriver e com sybase jaguar server dbauthlogfile dbauth log or the name of the EJB Server log file optional e com sybase jaguar service roleservice AseAuth DbAuth 165 Replacing an EJB Server See All Properties on page 149 for information on how to set these options 8 Start the EJB Server See Starting EJB Server independently on page 25 9 Reimport packages from the Repository 10 Reconfigure the connection caches 166 CHAPTER 11 EJB Server Naming Services A naming service lets you associate a logical name with an object such as a package and component Naming helps EJB Server applications easily locate an object anywhere on a network then implement the referenced object The naming service binds a name to an object The combination of bound name and its referenced
52. B clients can begin transactions using the javax transaction UserTransaction interface Obtain an instance from the initial naming context by resolving the name javax transaction UserTransaction For example import javax transaction import javax naming Context ctx ctx has been initialized UserTransaction uTrans UserTransaction ctx lookup Javax transaction UserTransaction You can call the begin commit and rollback methods to begin and end transactions You can enlist multiple component methods in a transaction with these restrictions 106 CHAPTER 7 Creating Enterprise JavaBean Clients Each method must allow inheritance of an existing transaction context That is the method s transaction attribute must be Supports Requires or Mandatory Methods with other transaction attributes run outside the scope of your transaction See Transactions tab component properties on page 77 for more information on transaction attributes All components must be on the same server and all must use the same transaction coordinator All methods must be invoked by the thread that began the transaction Serializing and deserializing Bean proxies To serialize a proxy To deserialize the proxy Serialization allows you to save a Bean proxy as a file Deserialization allows you to extract the proxy from the file in another process or on another machine and if the component instance is still active reestablis
53. By separating the functionality from the GUI you can easily upgrade and change the functionality of your program without having to change the GUI In addition multiple clients can use components at the same time The EJB Server execution engine EJB Server s runtime engine provides a scalable and platform independent environment for the execution of component based applications EJB Server is scalable because it is multithreaded and multiprocessor safe The EJB Server execution environment is the same across all platforms The EJB Server runtime engine provides these services e Network listeners for the connections on which clients send remote component invocations EJB Server s core network server technology is based on Sybase s Open Client Server technology e An execution environment for middle tier components See Server side component support on page 7 e A built in HTTP server You can use EJB Server s HTTP support to deploy your application s Java applets and HTML pages e Ability to run with different Java virtual machines e Connection caching You can define caches of connections for interacting with databases from EJB Server components See Connection caching on page 13 for more information In addition to these built in services you can install service components that run in the background and provide customized services to clients or other components CHAPTER 1 About EJB Server Compon
54. Components This chapter describes how to install modify and deploy Enterprise JavaBeans in EJB Server packages using the Adaptive Server plug in If your site uses PowerJ see the PowerJ documentation for information on deploying EJB classes directly to EJB Server from PowerJ Topic Page Packages and Enterprise JavaBean components 6e Importing Enterprise JavaBeans 71 Installing components 74 Modifying components 75 Configuring component properties 75 Generating stubs and skeletons 86 Creating Enterprise JavaBeans 87 Modifying packages 93 Configuring package properties 94 Exporting packages to EJB JAR files 95 Packages and Enterprise JavaBean components In the Adaptive Server plug in EJB Server packages allow you to group related EJB components as a logical unit Typically components in a package work together to provide a coherent service or function You can create JavaBeans from scratch or more likely import the JavaBeans to EJB Server using the Adaptive Server plug in When you import JavaBeans they must be contained in a JAR file or Java class file The Adaptive Server plug in reads the JAR file or class file and creates an EJB Server package containing a component for each Bean in the file See Importing Enterprise JavaBeans on page 71 EJB Server packages serve the following purposes 69 Packages and Enterprise JavaBean components Default packages 70 They are a un
55. If you start a transaction before you create an XAConnection EJB Server creates the connection and enlists it in the transaction Dynamic enlistment allows you to do this connl dsl getConnection A CHAPTER 5 Understanding Transactions and Component Lifecycles user_transaction begin Tf conn2 ds2 getConnection conn3 ds3 getConnection B conn2 close user_transaction commit Cc conn3 close connl close Where at these points the following are true A conn is not part of any transaction B conn1 conn2 and conn3 are part of the user_transaction C conn and conn3 are not part of any transaction You can get only one connection per resource Each getConnection call for the same database returns the same connection Warning XA performance diminishes when connections span methods Entity Bean local diamonds An entity object accessed from more than one path in the same transaction as shown in Figure 5 3 is called a diamond A local diamond exists when the access paths originate from and the entity object resides on the same server Typically EJB Server uploads data from the database at the beginning of a transaction and downloads data to the database at the end of a transaction When more than one program accesses an Entity Bean within the same transaction this can lead to inconsistent views of the data For instance if Program B updates the e
56. In a PowerJ program the transaction object handles the database connection Its properties store information about the database you want to connect to and it manages SQL transactions via commits and rollbacks CHAPTER 9 Developing Applications with PowerJ and EJB Server Query object The transaction object is in the Database page of the component palette To add a transaction object to your form you select the transaction icon in the palette and click on the form If you used the database option in the Form wizard the transaction object is added automatically Transaction properties The transaction object has properties for connection and transaction management You can set them in the wizard or on the object s property sheet You need to specify the JDBC driver and the URL for the database among other properties You can also specify that you want to connect to the database automatically when the form is created whether each database operation gets committed automatically when it is completed and whether updates are allowed You can also set properties at runtime It is typical to let the user specify a user ID and password and set the Userld and Password properties in code The following code sets these properties with values saved in string variables transaction_1l setUserID userid transaction_1l setPassword password Connecting If you have not set up AutoConnect behavior you can connect to the database using the conn
57. J and EJB Server This chapter gives an overview of how to develop distributed Web and client server applications with PowerJ and EJB Server You ll find information about the objects and code that make up the pieces of an application and the ways PowerJ and EJB Server together can provide business solutions Topic Page About the development process 119 Building distributed and Web applications that use EJB Server 128 Building client server applications using JDBC 137 Building Enterprise JavaBeans 1 1 components 141 About the development process What you can build This chapter describes scenarios for developing the following kinds of applications e Distributed or Web applications using EJB Server in the middle tier e Client server applications Applets applications components and Web server extensions There are several types of Java programs applets applications components and Web server extensions PowerJ generates behind the scenes code for each of these types so that you don t have to write as much code for the mechanics of the program You can concentrate on program specific code Applets An applet is a Java program that requires a host program such as a browser to run An applet is usually part of an HTML page and is downloaded when it is needed You don t have to deploy applets to individual computers Because they are downloaded as needed applets should be small so users don t get impatient w
58. Library the Solved Cases page and Sybase Powersoft newsgroups To access the Technical Library Product Manuals Web site go to Product Manuals at http www sybase com support manuals Technical documentation at the Sybase Web site is updated frequently For the latest information on product certifications 1 Point your Web browser to Technical Documents at http www sybase com support techdocs 2 Select a product from the product pick list and click Go 3 Select the Certification Report filter specify a time frame and click Go 4 Click a Certification Report title to display the report For the latest information on EBFs and Updates 1 Point your Web browser to Technical Documents at http www sybase com support techdocs 2 Select EBFs Updates Enter user name and password information if prompted for existing web accounts or create a new account a free service 3 Specify a time frame and click Go 4 Select a product 5 Click an EBF Update title to display the report To create a personalized view of the Sybase Web site including support pages Set up a MySybase profile MySybase is a free service that allows you to create a personalized view of Sybase web pages 1 Point your Web browser to Technical Documents at http www sybase com support techdocs 2 Click MySybase and create a MySybase profile This book uses these font and syntax conventions for Java items xiii Transact SQL syntax conventi
59. Open Architecture XA standards This option uses the Transarc Encina transaction coordinator that is built into EJB Server The Encina transaction coordinator uses two phase commit to coordinate transactions among multiple databases The default coordinator is the Shared Connection coordinator To view or change the coordinator use the Server Properties dialog box in the Adaptive Server plug in Components in EJB Server have a transaction attribute that indicates how a component participates in transactions You can view and change a component s transaction attribute using the Adaptive Server plug in the attribute is displayed on the Transactions tab in the Component Properties window The attribute has the following values e Not Supported The Default The component s methods never execute as part of a transaction If the component is activated by another component that is executing within a transaction the new instance s work is performed outside of the existing transaction CHAPTER 5 Understanding Transactions and Component Lifecycles e Supports Transaction The component can execute in the context of a EJB Server transaction but a connection is not required in order to execute the component s methods If the component is instantiated directly by a base client EJB Server does not begin a transaction If component A is instantiated by component B and component B is executing within a transaction component A execute
60. SE SYBASE_EJB html classes ten 3y Other variable substitutions or shell aliases such as to indicate your home directory are not allowed If you specify a relative path such as myclasses the path is interpreted relative to the EJB Server SYBASE SYBASE_EJB html classes directory 4 ClickOK CHAPTER 7 Creating Enterprise JavaBean Clients Java packages Compiling stubs For each IDL module Java equivalents for all interfaces types and exceptions that are defined in the module are generated to a single Java package The default Java package name is specified by the module s name or its Javadoc package comment If the module has a line of this form in the doc comment stubs are written in the specified Java package xx lt JjavaPackage dotty package gt where dotty package is the dot format Java package name If the doc comment does not specify a Java package stubs are generated to a package that matches the IDL module name For example stubs for module foo bar are generated in Java package foo bar For each IDL interface that is assigned to a component the Adaptive Server plug in generates a Java interface with the same name as the IDL interface a stub class that implements that interface a helper class and a holder class For example for an IDL interface named Calculator Calc the Adaptive Server plug in creates the source files listed in the following table Table 7 1 Java stub source files f
61. Server transaction reserve Sealstudent couse enroll student course addTo Bill student cowse StudentBiling To be correct both the database update made by the Registrar and the update made by the StudentBilling components must occur or neither must occur In other words if the student cannot be billed the course s available seats must not be changed To handle this case you could add logic to the enroll method to undo changes requiring an unreserveSeat method in Registrar However as more components are added to the scenario the logic needed to undo previous changes quickly becomes unmanageable It is much easier to define all the participating components to use EJB Server transactions Then an error in any component can induce a rollback of all changes made by the other participating components before the error occurred By defining the participating components to use EJB Server transactions you can be sure that the work performed by the components that participate in a transaction occurs as intended Defining transactional semantics To define how a component participates in transactions you must 1 Choose a transaction coordinator The transaction coordinator manages the flow of transactions that involve more than one connection Transaction coordinators on page 58 describes the available options 57 The EJB Server transaction processing model Transaction coordinators Transactional
62. Servers eee eeeeeeeeeeeeeeeeneeeeneeeeneeeeeeeenee 26 Verifying the status of EJB Servet c ccceeeceeeeeseeteeeeeees 27 INFORMATION FOR DEVELOPERS Enterprise JavaBeans Overview ssecccesccessseeeeseeeesseeseeeeeeeeees 31 About Enterprise JavaBean component ceeceeseeeeeeeeereeees 32 EJB Component type ee eeeeeeeeeeseeeeseeeeeeeeeseeeteaeeeeneeeneees 33 EJB transaction attribute values eee eee eeeeeeeeneeeeeetenes 35 EJB container SCrViCeS 0 00 eee eeeceeeseceeeeeeeeeeeeneeteaeeeeneeenaeees 37 EJB SuppOMte c824i se ei phatias pasta aden weber danke iene eels 38 Running EJB components in EJB Server 38 EJB clients connecting to EJB Server eere 39 Creating Component Based Applications cs sccssseeseeees 41 Application architecture 00 eee eeeeeeeceeeeeeeeeeeeeeeeseaeeeeeeeneeeeneneeee 42 Designing the application eee eee eeeeeeeeeeeeeeeeeneeseseeeeeeneeeeaes 44 Implementing components and clients eee eee eeneeeeneeeeeees 46 Deploying the application eee eee eeeeeeseneeeeeeeeneeseseeeeeeeeeeaes 48 Deploying COMPONENES ee eeeeeeeeeeeereeeeeeeeeeeteneeeeeeeeeeeaes 48 Developing clients 20 0 eee eee eeeeeeeeeeeeeeeeteneeeeeaeeseeneeteneeeeaes 49 Understanding Transactions and Component Lifecycles 51 Component lifecycles 2 0 eeeeeeseeeeseeeeeeeeceeneseenersenereneeeeeaneeseenerses 51 The EJB Server transaction processing Model
63. a w SYBASE EJB Server User s Guide Adaptive Server Enterprise 12 5 DOCUMENT ID 33690 01 1250 01 LAST REVISED June 2001 Copyright 1989 2001 by Sybase Inc All rights reserved This publication pertains to Sybase database management software and to any subsequent release until otherwise indicated in new editions or technical notes Information in this document is subject to change without notice The software described herein is furnished under a license agreement and it may be used or copied only in accordance with the terms of that agreement To order additional documents U S and Canadian customers should call Customer Fulfillment at 800 685 8225 fax 617 229 9845 Customers in other countries with a U S license agreement may contact Customer Fulfillment via the above fax number All other international customers should contact their Sybase subsidiary or local distributor Upgrades are provided only at regularly scheduled software release dates No part of this publication may be reproduced transmitted or translated in any form or by any means electronic mechanical manual optical or otherwise without the prior written permission of Sybase Inc Sybase the Sybase logo ADA Workbench Adaptable Windowing Environment Adaptive Component Architecture Adaptive Server Adaptive Server Anywhere Adaptive Server Enterprise Adaptive Server Enterprise Monitor Adaptive Server Enterprise Replication Adaptive Server Ever
64. a and maps the relational column values to fields in the implementation class This model corresponds to the Bean Managed Persistence model required by the EJB 1 1 specification Automatic persistence In this technique EJB Server manages the storage and retrieval of persistent data e Generated class In this technique a generated Java class saves and restores component state from a remote database The Adaptive Server plug in does not generate such classes but third party tool vendors can use this option The generated class can inherit from or delegate to the component s implementation class to save and restore component state Using component managed persistence To use component managed persistence you must configure the component s persistence properties and implement the required methods from the EntityBean interface Display the Component Properties window in the Adaptive Server plug in and configure the following fields on the Persistence tab e Persistence Choose Component Class Primary Key Enter the name of the primary key type see Allowable primary key types on page 89 In most cases no other persistence settings are required You can delegate to EJB Server s built in storage components rather than implementing your own database access code If you do so configure the Storage Component Connection Cache and Table fields see Storage components on page 116 Using automatic persistence Wh
65. a client applet Deploying a client application In PowerJ you compile your Java classes with the Build command Testing the distributed or Web application requires access to the EJB Server on either your own machine or another machine accessible to you When PowerJ builds an applet it generates an HTML file with an APPLET tag that you can use for testing You can copy the APPLET tag from the generated file into the HTML file you are developing for your applet PowerJ provides a WebApplication target type that you can use to collect all the files that you want to deploy After you build the client application you can test it within PowerJ You can run in Debug or Release nondebug mode When you are ready to deploy the application to a user s machine you can check the CLASSPATH directories that Power is using so that you can set the CLASSPATH correctly for the users Building client server applications using JDBC How it works Client server architecture means an application that connects directly to a database Business logic and the user interface are implemented together on the client Your application may also have business logic as stored procedures in the database In Java applications the database connection is made using JDBC Java client Database application server Corporate data JDBC tl 137 Building client server applicati
66. addresses Transaction management to simplify the design and implementation of an application s transactions Transparent thread safety features to simplify use of shared data and resources CHAPTER 1 About EJB Server Features e Result set support to enable efficient retrieval of tabular data in client applications e Support for Enterprise JavaBeans EJB components developed according to version 1 1 of the Enterprise JavaBeans specification The following sections explain these features and describe how EJB Server works EJB Server is for deploying transaction intensive business applications on the Internet These applications move beyond one way dynamic updates or data collection to real time two way updates of business critical information You can also migrate traditional client server transactional applications to multitier EJB Server applications EJB Server provides a framework for deploying the middle tier logic of distributed component based applications EJB Server s high performance transaction server provides efficient management of client sessions threads database connections and transaction flow EJB Server s scalability and platform independence allow you to develop your application on inexpensive uniprocessor machines then deploy the application on an enterprise grade multiprocessor server Client side logic for enterprise applications must be as small and efficient as possible to conserve network ban
67. age Application architecture 42 Designing the application 44 Implementing components and clients 46 Deploying the application 48 41 Application architecture Application architecture EJB Server architecture 42 EJB Server applications are composed of clients and an EJB Server that hosts components The clients can run on different machines the components execute on the host server machine as part of the EJB Server process Components in turn connect to databases on the host server machine Building EJB Server applications is different from building standard client server applications in that the parts of the application communicate with each other in a variation of traditional three tiered architecture In traditional three tiered architecture the client resides on the first tier the application server and components reside on the second tier and remote databases reside on the third tier In the EJB Server three tiered architecture see Figure 4 1 the databases reside on the same host as the EJB Server They communicate using a Sybase high speed JDBC driver through shared memory Executing methods on a component from the client or another component retrieving data from databases and other communications are managed by the EJB Server EJB Server handles the details of transactions threads security database connections and network communication so that you can concentrate on writing the business logic and user interface
68. aiting for the applet to start 119 About the development process 120 Because applets are downloaded they are subject to restrictions so they can t harm the user s system For example applets cannot access the local file system and can make connections only back to the server they came from Your applet class will extend the standard class java applet Applet which provides default implementations for the init start stop and paint methods In your applet source file PowerJ generates code to override the init method Applications A Java application behaves like any other program In Java terminology an application is a Java program that does not require a host server or browser to run The user sees windows and menus and interacts with controls The application can connect with a middle tier or database server Since applications must be locally installed rather than downloaded each time they are run they can be larger than applets The user s class path environment variable must include the directories containing the application s code files A standalone application has a main method that runs when the application starts It includes a main form and can include other forms including dialog boxes and frames with menus Components Components are standardized reusable pieces of software that are hosted in another program You can install them in servers that are designed to host components like EJB Server or include
69. al e ejb ref name The name of the Bean used in the application component 173 JNDI support e ejb ref type The Bean type Entity or Session e home The expected Java type of the home interface e remote The expected Java type of the remote interface e ejb link This is optional This code sample illustrates how to use JNDI to look up the home interface of the Employee enterprise Bean Get the default initial JNDI context Context initContext new InitialContext Look up the home interface of the Employee enterprise Bean Object result initContext lookup java comp env ejb Employee Convert the result to the correct typ EmployeeHom mpHome EmployeeHome javax rmi PortableRemoteObject narrow result EmployeeHome class Declaring an EJB link You can define a link from an EJB reference to an enterprise Bean by declaring an ejb link element in the deployment descriptor The application component and the target enterprise Bean must be in the same J2EE application This sample code creates a link to the Employee enterprise Bean by adding an ejb link element to the Bean s EJB reference definition lt ejb ref gt lt description gt Reference to the Employee entity Bean lt description gt lt ejb ref name gt e jb Employee lt ejb ref name gt lt ejb ref type gt Entity lt ejb ref type gt lt home gt com wooster empl EmployeeHome lt home gt lt remote gt c
70. ame password as the name server If the bindpassword property is empty or does not exist in the property file for a name server the name server accepts binds from any source Using an LDAP server with EJB Server To add persistent object name storage capabilities to EJB Server you can use an external directory naming service such as an LDAP server The EJB Server properties include an optional URL for specifying the port for the external name server When you use an external name server EJB Server uses JNDI to communicate with the name server through the specified URL 177 Using an LDAP server with EJB Server LDAP object schema and EJB Server objects LDAP servers have predefined schema for common objects such as country organization and organizational unit EJB Server uses the following format for an LDAP compatible initial context ou lt organizational unit gt o lt organization gt c lt country gt Storing EJB Server object bindings on an LDAP server When you use an LDAP server with an EJB Server name server the CosNaming component binds all implemented objects on the servers that use the designated EJB Server name server and stores the name context information on the LDAP server If EJB Server detects previously bound objects on the external name server it updates the existing bindings with current name context information When you shut down the EJB Server it unbinds the stored information 178 To connect
71. and click Ok e Delete Removes the package from EJB Server and from the repository Configuring package properties General tab properties Role Mapping properties 94 The Package Properties window has three tabs e General e Role Mapping e All Properties The following table describes the properties on the General tab Table 6 3 Package properties General tab Property Description Commenits Example Description A description of the package View or change the description of The description can be up to an existing component or set the 255 characters description of a new one You can map permissions for component methods to roles defined in Adaptive Server See Permissions and roles on page 15 for more information about roles in EJB Server If you want to restrict access to a Bean you must for each method e Include a J2EE role at the method level when you create the Bean e Map the J2EE role to an Adaptive Server role in the Role Mapping dialog box To map a J2EE role to an Adaptive Server role 1 If necessary define a new Adaptive Server role See the Adaptive Server Administration Guide for instructions 2 Select the Role Mapping tab from the Package Properties window 3 Click Add Double click the J2EE role and enter a J2EE role name You can also enter a description for the role in the provided field CHAPTER 6 Working with EJB Packages and Components 4 Select an Adaptive Server role
72. aphical user interface that allows you to manage both Adaptive Server and EJB Server You can use EJB Server without further configuration but to customize EJB Server for your installation see Chapter 10 Configuring EJB Server The following sections describe enabling and starting EJB Server and the Adaptive Server plug in for Sybase Central so that you can perform these basic tasks yourself after installation The installation and configuration process will start Adaptive Server enable the EJB Server option start EJB Server and start the Adaptive Server plug in to Sybase Central 21 Basic tasks Using the Adaptive Server plug in to Sybase Central The Adaptive Server plug in runs within Sybase Central Use the Adaptive Server plug in for Sybase Central to configure EJB Server and to define and deploy software components and packages An EJB Server must be running before Sybase Central can connect to it You must have the System Administrator role in Adaptive Server to use the Adaptive Server plug in The installation process creates this role EJB Server is preconfigured so that you can start up and run the server You may need to configure EJB Server further to run your applications What you can do from From the Adaptive Server plug in you can the Adaptive Server plug in e Replace EJB servers e Shutdown and restart EJB Servers e Add or drop connection caches e Add drop export or deploy packages e Add
73. ation For Internet applications this machine must be available to clients that are outside your corporate firewall Components must be installed in a package before they are available for use in applications You should install components that perform related tasks together in a single package Chapter 6 Working with EJB Packages and Components describes how to create packages in the Adaptive Server plug in CHAPTER 4 Creating Component Based Applications Define components Packages are the units of deployment for your application you can use the Adaptive Server plug in to import and export archives of a package its installed components and related application files For example you can deploy a tested configuration by exporting packages from your test server and importing them into the production server For more information see Deploying components on page 48 Packages are also one level in the EJB Server authorization hierarchy You can edit the package s required Role Memberships to restrict which users can access components in the package For each component you must choose the component model design the component interface determine transactional semantics and define the component in EJB Server Choose the component model Choose the component model based on your development team s expertise Server Side Component Support on page 7 describes the available component models Design the transactio
74. atures and other properties such as component type transaction support threading model and the name of the Java class or executable library that implements the component Before a client application can execute a component the component must be installed in an EJB Server package and that package must be installed in the server to which the client connects EJB Server provides a Refresh menu item to refresh components packages and servers This option lets you test and debug component implementation changes without restarting EJB Server Client session and component lifecycle management 10 EJB Server client sessions are established internally by the client stubs and proxies that applications use to invoke EJB Server component methods A component s lifecycle determines how instances are allocated bound to client sessions and destroyed EJB Server manages both client sessions and component lifecycles without requiring specialized knowledge on the part of the application developer CHAPTER 1 About EJB Server Client session management Component lifecycle management Internally the stub or proxy object establishes a network connection between the EJB Server and a remote client The stub proxy model discussed in Client stub proxy support on page 8 requires user authentication parameters to instantiate a stub or proxy object The communication protocol is also determined when the stub or proxy object is instantiated O
75. ava When the component Pooling option is set in EJB Server the Java canReuse method is not called even if the component implements the ServerBean Java interface A component that can remain active between consecutive method invocations is called a stateful component A component that is deactivated after each method call and that supports instance pooling is said to be a stateless component Typically an application built with stateless components offers the greatest scalability Stateful components A stateful component remains active across method calls Since deactivation happens at the mercy of client applications you may wish to configure the Instance Timeout property for stateful components so that a client cannot monopolize a component instance indefinitely See Resources tab component properties on page 80 for more information Stateless components In order for a component to be stateless both of the following must be true CHAPTER 5 Understanding Transactions and Component Lifecycles e You have configured or implemented the component to be deactivated after every method invocation In the Adaptive Server plug in you can enable the Automatic deactivation demarcation property for the component located on the Transactions tab in the Component Properties window Alternatively you can implement the component so that it calls either completeWork or rollbackWork in every method e You have enabled the Pooling opti
76. ava comp env context e env entry type The environment property s Java datatype must be one of Boolean Byte Double Float Integer Long Short or String e env entry value The environment property value which is optional Within the same container all instances of an application component share the same environment properties The component instances cannot modify the environment at runtime An application component instance uses the JNDI interfaces to locate the environment naming context and access the environment properties To locate the naming context an application creates a javax naming InitialContext object and gets the InitialContext for java comp env In this example the application retrieves the value of the environment property maxExemptions and uses that value to determine an outcome Context initContext new InitialContext Context myEnv Context initContext lookup java comp env Get the maximum number of tax exemptions Integer max Integer myEnv lookup maxExemptions Get the minimum number of tax exemptions Integer min Integer myEnv lookup minExemptions Chapter 11 EJB Server Naming Services EJB references Declaring an EJB reference Use these properties to customize the business logic if numberOfExemptions gt max intValue numberOfExemptions lt min intValue throw new InvalidNumberOfExemptionsException
77. ave to be re created with each use An EJB component can manage its own persistence by means of the logic you provide in the Bean or delegate persistence services to the EJB container Container managed persistence means that the data appears as member data and the container performs all data retrieval and storage operations for the EJB component See Chapter 8 Managing Persistent Component State for more information 37 EJB support EJB support EJB Server can host EJB components developed according to version 1 1 of the Enterprise JavaBeans specification EJB Server supports session Beans and entity Beans with Bean managed persistence or container managed persistence See the complete EJB 1 1 specifications from Sun Microsystems at http java sun com products ejb Running EJB components in EJB Server You can run Enterprise JavaBeans as EJB Server components using any of these techniques 38 Define EJB components in PowerJ using wizards to define the interfaces and deploy the Bean directly from PowerJ to EJB Server See the PowerJ documentation for more information Use the Adaptive Server plug in to Sybase Central to import an EJB JAR file that contains the classes and deployment descriptors for one or more EJB components The Adaptive Server plug in defines components with properties matching the deployment descriptor settings Import compiled versions of a home interface remote interface implementati
78. base Java applets are downloaded to clients which instantiate components on the server Client applications are installed on client machines from which they also instantiate components on the server An applet or application manages presentation and interaction with an end user Components running on EJB Server handle much of the application processing The database stores manages and processes the data If the client is an applet users find and launch applications from traditional HTML pages Instead of simply loading a static page EJB Server downloads an executable applet to the individual s browser If the client is an already installed application the user launches the application from his or her machine Clients communicate directly with an application component running on EJB Server Server components access data from one or more databases apply business logic and return results to the client applet for display When a proxy object is created on the client applet it instantiates a corresponding component registered with the EJB Server On the server side a component is instantiated in response to a request from the proxy object running in the client environment A method on a component is executed when it is invoked by a proxy object on the client applet Developing an application There are three basic steps involved in creating and deploying an EJB Server application that employs a Java applet as a client 19 Termino
79. be Requires Transaction so that the balance query the billing calculation and the debit of the student s balance always occur in the same transaction In the Enrollment component the enroll method first calls Registrar reserveSeat After Registrar reserveSeat returns the method checks whether the transaction is still viable using the isRollbackOnly primitive If the transaction is viable the method calls StudentBilling addToBill Here is the pseudocode for Enrollment enroll invoke Registrar reserveSeat if isRollbackOnly returns true return else invoke StudentBilling completeWork endif The transaction attribute for Enrollment must be Requires Transaction so that the work done by StudentBilling and Registrar occurs as a single transaction Dynamic enlistment in Bean managed transactions 64 EJB Server supports dynamic enlistment for Bean managed transactions which allows you to create a connection in one method of a stateful Bean use the connection in another method and close the connection in a third method For a JDBC 2 0 shared connection PooledConnection the container manages the single connection s enlistment and deenlistment in transactions For XA connections the Object Transaction Service libraries need to know all the resources that will participate in a transaction when it starts If you get an XAConnection before you start a transaction EJB Server enlists the XAConnection in the transaction
80. cations 129 applications EJB Server architecture of 42 creating 41 defining components for 46 deployment of 48 designof 44 introduction to 41 architecture EJB component 32 EJB Server 42 of EJB Server applications 42 AseAuth package 70 165 B basic tasks 21 27 bindpassword 177 building components 47 EJB Server applications 41 business logic and EJB Server components 128 C caches connection support for 13 character sets 12 conversions 12 classes Java for EJB components 92 classpath environment variable 155 CLASSPATH environment variable 129 137 155 client session management 11 client server applications Java 119 137 clients deployment of 49 design considerations for 47 development process for 46 EJB 97 session management and 10 types of 8 code set See Also character sets comma in SQL statements xv compiling 179 Index Java stubs 99 component definition 18 executing methods on 19 instantiating 19 restarting after modifying 146 155 component lifecycle management of 11 component models supported 18 component transaction server see EJB Server components building 47 client stubs and proxies for 8 configuring properties for 75 creation and destruction of 11 52 defining 45 definition of 10 deploying 92 design of 45 development process for 46 EJB 31 32 69 installing toa package 75 introduction to 7 lifecycle management 11 lifecycle of 51 52 overview 7 persistent 109 Powers
81. cause of the error 158 Chapter 10 Configuring EJB Server If you change the cache properties to correct the problem you must refresh the cache before testing again Managing XA resources EJB Server uses the two phase commit protocol for distributed transactions To use this feature your Adaptive Server installation must have a valid ASE_DTM license You can use the Adaptive Server plug in to Enable the OTS XA feature for EJB Server Create XA connection resources for accessing Adaptive Server Setting up XA resources This section describes procedures for configuring and enabling XA resources on Adaptive Server and EJB Server oe To configure Adaptive Server and EJB Server for XA resources You can also perform steps 2 and 4 from the Adaptive Server plug in 1 Make a copy of the SYBASE SYBASE_EJB config afconfig dat file and move the copy to a secure location If the XA configuration process fails you will need to copy an uncorrupted version of this file back into the release area before reconfiguring XA resources Enable Distributed Transaction Management DTM on Adaptive Server sp_configure enable dtm 1 Run the script sglserver12 sql located in SYBASE SYBASE_EJB html classes sp Grant the dtm_tm_role system role to the user in Adaptive Server sp_role grant dtm_tm_role user_name Create the OTS XA transaction log device in SYBASE SYBASE_EJB e From the UNIX command shell execut
82. ce or the Beans session timeout value has not expired EJB Server may serialize the instance and save it to disk to conserve memory EJB Server calls the passivate method before serializing the Bean and the activate method when the Bean has been deserialized In the code for these methods you must release and reacquire any object references that do not support serialization Building a Java client for a distributed or Web application Types of clients Enterprise JavaBeans model for clients General procedure 136 The Java client in a EJB Server distributed application can be an applet or an application depending on whether you want your client to run in a Web browser EJB Server supports the EJB 1 1 client model using stubs that call the EJB Server CORBA ORB Creating a Java client for EJB Server involves these general steps 1 In PowerJ add the EJB Server component This creates a proxy on the PowerJ component palette 2 Add a proxy object and PowerJ InitialContext object to your client 3 Write code that e Calls component methods by calling the corresponding method in the stub class e Cleans up client side resources by setting proxy references to null This expedites Java garbage collection 4 Execute the Build command to compile your Java client and then deploy it CHAPTER 9 Developing Applications with PowerJ and EJB Server Compiling and deploying the Java client What you do Setting up and publishing
83. come of B s transaction if B is not executing in a transaction then A executes in a new transaction Mandatory Methods may only be invoked by a client that has an outstanding transaction Bean Managed For EJB session Bean components only The component can explicitly begin commit and rollback new independent transactions by using the javax transaction UserTransaction interface Transactions begun by the component execute independently of the client s transaction If the component has not begun a transaction the component s database work is performed independently of any EJB Server transaction Stateless session Beans can use this attribute but transactions begun in a method must be committed or rolled back before that method returns Otherwise EJB Server logs an error and returns an exception to the client Stateful session Beans can create transactions that remain open across several method calls Never The component s methods never execute as part of a transaction and the component may cannot be called in the context of a transaction If a client or another component calls the component with an outstanding transaction EJB Server throws an exception Instances tab component properties 78 Properties on the Instances tab configure how instances of the component are created and bound to server side threads and client side object references The properties are as follows CHAPTER 6 Working with EJB Packages and Components
84. commended EJB Server checks for timeouts after each method returns Your component will not be deactivated in the middle of an invocation because of a timeout When a transaction times out the next method invocation in the client side ORB throws the CORBA TRANSACTION_ROLLEDBACK system exception To set Transaction Timeout for a server display the All Properties tab in the Server Properties window Then set the com sybase jaguar server tx_timeout property Network transport time is included in the measured timeout period You may need to configure a larger timeout period if clients connect over slow networks Instance Timeout Specifies how long in seconds an active component instance can remain idle between method calls before the client s proxy becomes invalid If the timeout expires the instance is automatically deactivated Instance Timeout is useful for ensuring timely deactivation of stateful components Stateful versus stateless components on page 54 explains this term The setting has no effect for stateless components When the timeout period is exceeded EJB Server deactivates the component and invalidates the client s object reference If the client attempts another method invocation the client side ORB throws the CORBA OBJECT_NOT_EXIST exception At this point the client must create a new proxy instance for the component This property is not set for new components the component inherits a default value from th
85. configuration tasks Before you use EJB Server To use EJB Server effectively you should be able to create programs in the Java Enterprise JavaBeans programming language and component model You should also know how to retrieve and update information in databases and be familiar with component technology concepts 17 Terminology and concepts Terminology and concepts This section explains some of the basic concepts and terminology associated with developing component based EJB Server applications It is intended primarily to provide you with enough information to begin using the Adaptive Server plug in for Sybase Central For detailed information on EJB application development refer to Chapter 6 Working with EJB Packages and Components Terminology An EJB application consists of one or more packages and a client application or applet Packages consist of components and components are made up of one or more methods 18 EJB Server hosts manages and executes JavaBean components In the EJB environment a component is simply an application object that consists of one or more methods JavaBeans typically execute business logic access data sources and return results to the client Clients applets create an instance of a component and execute methods associated with that component Components run strictly within the EJB Server A package is a collection of components that work together to provide a service or some
86. ct the query If you want to change the SQL statement at runtime you can use the setSQL method String userStatement select from dba employee query_1l setSQL userStatement Executing the query If you set the query s AutoOpen property your program will automatically execute the query when the query object is created To execute the query at runtime you call the open method query_l open If the query s SQL statement returns a result set you can call methods that work with the data often using bound controls A data bound control is an object whose value is automatically updated by query results When you use bound controls you can display database data with very little coding effort For example you can bind a text box to a query object so that the text box always shows the value of a specified column in the current row If you move the cursor to a different row of data the text box automatically changes to show the value in the same column of the new row If the user changes the value of a bound control it typically changes the corresponding value in the query object s primary buffer For example if a text box displays the value of Column 1 changing the value of the text box typically changes the value of Column 1 in the current row as stored in the primary buffer Changes made in the primary buffer can be incorporated in the database itself using the update method A bound control such as a text box or ch
87. ction manager allows client sessions to share previously opened connections so that server CPU time and memory are not consumed by opening more connections than necessary e Improved scalability Since connection caching allows the same number of clients to be serviced using fewer connections less memory and other resources are required Support for transaction semantics EJB Server s declarative transaction model requires that you call the connection caching APIs to obtain and release all database connections To realize these benefits a component must be coded to use a cached connection only when necessary and to release the connection back to the cache at other times A component should not hold connections while waiting for more input from the client application As a general rule each method call that requires a third tier connection should take a connection handle when invoked and release it before returning JDBC 2 0 drivers provide implicit support for connection pooling When using JDBC drivers that do not conform to the JDBC 2 0 specification you can define a connection cache in the Adaptive Server plug in or PowerJ for your components use Transaction support requires cached connections If your component participates in EJB Server transactions you must use an JDBC 2 0 driver or define an EJB Server connection cache and obtain connections using the EJB Server connection manager classes Java components can use th
88. ctions to the database server avoiding the overhead imposed when each instance of a component creates a separate connection By establishing a connection cache an EJB Server can reuse connections made to the same data source 128 CHAPTER 9 Developing Applications with PowerJ and EJB Server Architecture of distributed and Web applications How it works In a distributed or Web application that uses Java and EJB Server together a Java client accesses the EJB Server which in turn accesses a database About the distributed In the distributed architecture the client is a Java application rather than an architecture applet The application and Java VM need to be installed on the user s machine and the application files made accessible to the Java VM About the Web A Web application is a variation on the distributed architecture where the client architecture is a Java applet hosted in a Web browser About the Web client The browser handles communication with a Web server via the HTTP protocol The Web page that contains the applet and the applet itself are downloaded via HTTP The applet then runs in the Web browser but bypasses the Web connection and communicates directly with the EJB Server Connecting directly to EJB Server enables persistent connections with the client and avoids the problems with stateless HTTP A major advantage of the Web architecture is that the client applet is downloaded when the Web page is requested You don
89. d JDBC datatypes JDBC SQL column Java field type CORBA IDL field type type boolean boolean TINYINT char char CHAR byte octet TINYINT short short SMALLINT int long INTEGER long long long BIGINT float float REAL CHAPTER 8 Managing Persistent Component State JDBC SQL column Java field type CORBA IDL field type type double double FLOAT java lang String CtsComponents String Value VARCHAR byte CtsComponents Binary Value VARBINARY java lang Boolean CtsComponents Boolean Value TINYINT java lang Character CtsComponents CharValue CHAR java lang Byte CtsComponents OctetValue TINYINT java lang Short CtsComponents ShortValue SMALLINT java lang Integer CtsComponents Long Value INTEGER java lang Long CtsComponents LongLong Value BIGINT java lang Float CtsComponents Float Value REAL java lang Double CtsComponents Double Value FLOAT java lang BigDecimal CtsComponents Decimal Value DECIMAL java lang Date CtsComponents Date Value DATE java lang Time CtsComponents Time Value TIME java lang Timestamp CtsComponents Timestamp Value TIMESTAMP Serializable object N A VARBINARY Values that can be null If a field can contain nulls do not use a primitive type Instead use the CtsComponents TypeValue IDL type and the equivalent Java object type For example rather than float use CtsComponents FloatValue and java lang Float Table schema for bina
90. de that allows the JavaBeans user to modify properties at design time There are specific standards and conventions for creating Beans Web server extensions You can create Web server extensions that follow the Java Servlet API You can deploy servlets in EJB Server or other Web servers that support Java Servlets For Web servers that do not directly support the Servlet API PowerJ provides a DLL that translates from CGI NSAPI or ISAPI to the Servlet API You use PowerJ to build most of the pieces of the applications described here Some of the activities for building a Java application are listed below Depending on which application architecture you choose some of these activities may apply to creating the client and others to creating the server 1 Create a workspace then create a target which is the type of program you want to build A workspace can include several targets where each target is a part of a larger application 2 Create the user interface by creating one or more forms and adding controls and nonvisual components 3 Optionally add menus by creating a frame a type of form adding a MenuBar object to the frame and using the Menu editor to design menus 4 Optionally access database data by adding transaction and query objects to the form Make the visual components of the form bound to the query object 5 Code application processing logic You can place this code in different locations e In events and methods f
91. del 55 verifying status 27 EJB Server properties 154 EJB Server roles 15 EJB Server runtime environment 20 EJB Server transactions benefits of 56 explanation of 56 EJB transaction attributes 35 enabling EJB Server 23 181 Index Enterprise JavaBeans See EJB Enterprise JavaBeans EJB components building with PowerJ 141 entity Bean 34 EJB component type 33 entity components definition of 109 environment variables CLASSPATH 155 classpath 155 events Java 127 F finder methods IDL design pattern for 90 G garbage collection Java configuring for EJB clients 103 general server properties description 147 generating EJB stubs 86 98 H HTTP protocol and EJB Server 129 support for 8 IIOP support for 8 initial context 168 installing components 74 instance pooling adding support for 54 182 configuring 79 definition of 52 instance timeout component property 80 instances component properties to configure allocation of 78 instantiating components 19 intercomponent calls and EJB Server transactions 56 interfaces EJB home 89 EJB remote 91 J J2EE roles 15 91 94 JAR file 71 EJB 1 1 71 95 Java components 120 packages for generated stubs 99 version for generated stubs 98 Java applications about 120 developing 15 Java classes for EJB components 92 Java clients compiling 99 Java Connection Manager classes 135 JavaBean components creating in PowerJ 121 jConnect database inter
92. der beneath the host Adaptive Server To disable EJB Server from the Adaptive Server plug in 1 Highlight the Adaptive Server host for the EJB Server 2 Select File Configure 3 Select enable enterprise java beans from the alphabetical list of configuration parameters 4 Change the number in the Value column to 0 5 Click OK CHAPTER 2 Getting Started To disable EJB Server using isq 1 Log in to Adaptive Server using isql 2 Enter sp_configure enabl nterprise java beans 0 Starting EJB Server automatically When the installation process is complete e EJB Server is running e EJB Server is configured to start up automatically each time Adaptive Server starts up Later on you can enable or disable automatic startup using the sp_serveroption system procedure For example to disable automatic startup enter sp_serveroption SYB_EJB external engine auto start false where SYB_EJB is the logical name of the EJB Server To enable automatic startup enter sp_serveroption SYB_EJB external engine auto start true Starting EJB Server independently Note Adaptive Server must be running before you can start EJB Server You can start or restart EJB Server in two ways e From the Adaptive Server plug in to Sybase Central e Using the sp_extengine system procedure To restart EJB Server from the Adaptive Server plug in 1 Right click
93. determines how methods in your component participate in transactions the setting affects all methods The transaction attribute can have the following values e Not Supported The component level default The component s methods never execute as part of a transaction If the component is activated by another component that is executing within a transaction the new instance s work is performed outside of the existing transaction e Supports The component can execute in the context of an EJB Server transaction but a connection is not required in order to execute the component s methods If the component is instantiated directly by a base client EJB Server does not begin a transaction If component A is instantiated by component B and component B is executing within a transaction component A executes in the same transaction 77 Configuring component properties Required The component always executes in a transaction When the component is instantiated directly by a base client a new transaction begins If component A is activated by component B and B is executing within a transaction then A executes within the same transaction if B is not executing in a transaction then A executes in a new transaction Requires New Whenever the component is instantiated a new transaction begins If component A is activated by component B and B is executing within a transaction then A begins a new transaction that is unaffected by the out
94. dwidth To accomplish this goal applications are partitioned into three parts presentation logic business logic and database logic The database resides on the bottom tier of the enterprise system to maintain and secure the organization s information assets The business logic resides in the middle tier The presentation logic is on the user s desktop or top tier or is dynamically downloaded to the user s desktop The EJB Server is responsible for executing and securing the vast majority of a corporation s business logic This makes it a critical component in the emerging network centric architecture The Web browser connects to EJB Server or a Web server via HTTP to download an HTML page containing a Java applet that performs presentation functionality The applet communicates with EJB Server calling middle tier components that perform business logic Adaptive Server stores processes and protects the corporate data EJB Server manages a pool of connections to the back end database coordinating the transaction processing to those servers Features Components are objects that reside on EJB Server and can be used by many different programs regardless of the program s programming language A client executes the methods in a component Instead of creating one massive program you create a client that contains the GUI and validation code and several individual components that contain the functionality or business logic of your program
95. e echo x dd seek 8k of server_nameOTSLog dev 159 Managing XA resources e From the DOS prompt on Windows NT execute Filevol server_nameOTSLog dev 4000K where server_name is the physical name of your EJB Server If you do not create a log file EJB Server will not start up 6 Shutdown and restart Adaptive Server To enable EJB Server for OTS XA transactions Enable the EJB Server for OTS XA transactions from the Adaptive Server plug in 1 Highlight the EJB Server folder Select File Properties Select the Transactions tab Select OTS XA Transactions Press OK nan A N Creating XA resources You must configure XA resources to access a specific database XA resources differ from connection caches in that XA resources are XA Library interfaces that maintain their own connection pool separate from the connection cache connection pool If a get connection call such as the Java getConnection method call is in a transaction the XA resource is automatically used to return a connection If a get connection call is not in a transaction the connection cache is automatically used If the transactional behavior for a component uses the Supported option then EJB Server determines at runtime whether the component executes its get connection calls in a transaction if it does you must configure both a connection cache and a corresponding XA resource for a database If you execute a transaction without an XA
96. e if you create a session Bean on a Web server that tracks a user s path through the site the session Bean is destroyed when the user leaves the site or idles beyond a specified time Stateless session Beans Entity Beans 34 A Stateless session Bean manages tasks that do not require the keeping of client session data between method calls Stateless session Beans have the following characteristics e Method invocations do not depend on data stored by previous method invocations e There is no affinity between a component instance and a particular client Each call to a client s proxy may invoke a different instance e From the client s perspective different instances of the same component are identical Unlike stateful session Beans stateless session Beans can be pooled by the server improving overall application performance An entity Bean models a business concept that is a real world object For example an entity Bean might represent a scheduled airplane flight a seat on the airplane or a passenger s frequent flyer account Entity Beans have the following characteristics e Each instance represents a row in a persistent database relation such as a table view or the results of a complex query e The Bean has a primary key that corresponds to the database relation s key and is represented by a Java datatype or class CHAPTER 3 Enterprise JavaBeans Overview EJB transaction attribute values Each EJB c
97. e Java Connection Manager JCM classes for connection caching The JCM classes manage JDBC connections The JCM classes are e com sybase jaguar jcm JCMCache Represents a configured connection cache and provides methods to manage connections in the cache e com sybase jaguar jem JCM Provides access to JDBC connection caches defined in the Adaptive Server plug in JCM methods return JCMCache instances To access a connection cache configure a Power transaction object to connect to the cache and use the transaction object Typically you will also use a query or DataStore object 135 Building distributed and Web applications that use EJB Server Instance pooling How it works Implicit pooling of EJB components Instance pooling allows EJB Server to maintain a cache of component instances and bind them to client sessions on an as needed basis When components support instance pooling the scalability of your application increases Instance pooling eliminates execution time and memory consumption that would otherwise be spent allocating unnecessary component instances Entity Beans and stateless session Beans can be implicitly pooled after any method invocation EJB Server calls the activate and passivate methods to indicate when an instance has been bound to a client session Stateful session Beans remain bound to a client session as long the server has not crashed the client has not called remove to unbind from the instan
98. e a user or a role in Adaptive Server that user and role are also valid in EJB Server To use the Adaptive Server plug in with EJB Server you must be a registered user in Adaptive Server and have the System Administrator role System Administrator roleSecurity for components is handled at the method level for each package You include a J2EE role in the method you want to restrict and then map that J2EE role to a role in Adaptive Server so that only users with that role can execute the method The Adaptive Server plug in allows you to map roles through each package for methods within the package See Configuring package properties on page 94 for more information PowerJ overview PowerJ is Sybase s RAD tool for Java development Even if you are not an experienced Java programmer you can use PowerJ to write sophisticated programs If you are an experienced Java programmer you can use the full facilities of Java whenever necessary Because PowerJ provides facilities that let you build and deploy components directly to the middle tier it is the ideal web development environment for EJB Server With PowerJ you can e Write Java code that takes advantage of the PowerJ component library a collection of Java classes that speeds the development process e Use object oriented programming features such as inheritance encapsulation and polymorphism to make your objects more reusable 15 Features 16 Create Java components t
99. e client when a transaction is rolled back Sybase recommends that you do not alter this setting com sybase jaguar component refresh This property specifies whether the component can be refreshed If the value is false the File Refresh option has no effect for the component Allowable values are true and false The default is true com sybase jaguar component java classes For Java components this property lists additional java classes that must be reloaded when the component is refreshed The property takes as values a list of fully qualified class names separated by commas You can specify all classes in a package using wildcards as in this example com xyz MyPackage You can specify all classes in a JAR file by specifying the JAR file name as in this example MyEntityBean jar The JAR file must be deployed in the SYBASE SYBASE_EJB java classes subdirectory 85 Generating stubs and skeletons Copies of the specified classes must be deployed under one of the following locations When loading classes required by Java components EJB Server searches for classes in this order 1 Any JAR file that is listed in the com sybase jaguar component java classes property and deployed in the EJB Server SYBASE SYBASE_EJB java classes subdirectory The class tree based at the SYBASE SYBASE_EJB java classes subdirectory The class tree based at the SYBASE SYBASE_EJB html classes subdirectory com sybase jaguar compon
100. e for component events Templates Database Intemet Utilities JClass JScape Lite Swing 125 About the development process Designing menus Accessing data 126 You add menus to your application with a MenuBar object A MenuBar object represents all the menus displayed by the form MenuBar objects can be added only to forms that are based on the Frame class To add a menu to your application you create a form whose type is Frame and drop a MenuBar object onto the form You can add individual menus and menu items in the Menu Editor accessed by selecting Edit Menu from the form s pop up menu Wi menu_1 BEI File View Menu Help Menu Layout Properties for menu_1_Item1 menu_1 3 Fie General E New Caption Open E Save Est E Save s Variable name suffix Separator Ek xil E Edit I Disabled Window Help I Checkable F Checked New Popup New Item In PowerJ you can use the transaction object to simplify connecting to many types of data sources You can use either the DataWindow Java Edition also known as the DataWindow JavaBeans component or the query object for SQL statements and data retrieval You use the query object if you want to use data bound controls instead of the DataWindow Both the DataWindow JavaBeans component and the query object can use the transaction object or they can process result sets without a database connection
101. e of parameter param in the finder method s IDL signature Note If the component was imported from an EJB JAR file the parameter names will not match those in the original Java implementation Instead they are p0 p1 and so forth param fieldName If method parameter param is not a simple type reference the value of field fieldName The following are examples of queries using placeholders This query returns all rows in a table select key from table This query uses the value of the expiryDate parameter to filter a range of closingDate column values select key from table where closingDate lt expiryDate Persistence for stateful components 114 Stateful components collect client session data over successive client method invocations Normally state data is stored in memory using fields in the implementation class You can manage persistence using these techniques Java serialization This model can be used only in EJB stateful session Beans To save persistent state EJB Server serializes the component class instance and saves the binary data to the database Automatic persistence In this model you define a state datatype in IDL or Java and implement component methods to receive state data read from the database and return state data to be written to the database EJB Server calls your state access methods and manages interaction with the database CHAPTER 8 Managing Persistent Compo
102. e server properties At the server level configure the instance timeout by displaying the All Properties tab in the Server Properties window Then set the com sybase jaguar server timeout property The timeout period is configured in seconds with O indicating infinity that is no timeout If the component s Instance Timeout property is not set the default is inherited from the server properties The default for a new server is 0 When specifying timeouts a resolution of 5 seconds is recommended Network transport time is not included in the measured timeout period You may need to configure a larger timeout period if clients connect over slow networks 81 Configuring component properties Persistence tab component properties 82 The Persistence tab allows you to specify an EJB entity Bean s primary key and configure settings that allow EJB Server to save component state to a database server Table 6 2 summarizes the Persistence settings See Chapter 8 Managing Persistent Component State for detailed information on these fields CHAPTER 6 Working with EJB Packages and Components Table 6 2 Persistence tab component properties Field Persistence Description Specifies whether component state is saved and if so how The available options are e None The default The component s state is not stored in a database Java Serialization For EJB stateful Session Beans only The component implementa
103. eck box displays values from a single database column Controls such as grids can display values from several columns To use an object as a bound control you check the Bound Control check box on the object s property sheet at design time You can t convert an ordinary control to a bound control at runtime Data for bound controls To associate data with the bound control you set the control s DataSource and DataColumns properties You can set them on the property sheet at design time or with the set methods at runtime The DataSource property specifies the query object to which the control will be bound To set its value at runtime use the control s setDataSource method textf_l setDataSource query_l CHAPTER 9 Developing Applications with PowerJ and EJB Server The DataColumns property determines which column s value is displayed by the bound control To set its value at runtime use the setDataColumns method The string identifying the column can be the column s name or number textf_l setDataColumns emp_id To specify multiple columns for controls such as grids you can list more than one column with entries separated by semicolons grid_l setDataColumns emp_id dept_id Data navigator PowerJ s data navigator control provides a simple way for the user to move through a database It displays forward and back buttons and buttons for adding editing and deleting rows Data navigators are bound c
104. ect method of the transaction object transaction_l connect Transaction management Ifyou have not set up AutoCommit behavior you can commit or roll back changes explicitly with methods of the transaction object transaction_1l commit transaction_1l rollback A query object represents a query on a specific database and can be used to execute any SQL statement After the transaction object connects to the database interactions with the database are done through query objects How the query object manages data A query object has several data buffers The buffers store the data as it was retrieved from the database the current state of the data rows that have been deleted and rows that are temporarily filtered out of view To update the database PowerJ generates SQL statements to modify the contents of the database so that they match the contents of the primary buffer Query object properties The query object has properties that associate it with a transaction object describe the SQL statement for the query and provide information necessary for updating the database such as primary key columns You can set the properties in the query object property sheet at design time or you can use query object methods at runtime 139 Building client server applications using JDBC Setting up data bound controls 140 For the SQL statement you can type the text in the property sheet or use the PowerJ Query Editor to constru
105. eeeeaeees 116 Supported Java IDL and JDBC SQL types eee 116 Table schema for binary Storage eeeeesceeeseeeeeeeeeneeeeneeteaes 117 CHAPTER 9 Developing Applications with PowerJ and EJB Server 119 About the development ProcesS eceesceeesceseeeeeeseeeeneeteneeeeaes 119 Creating workspaces targets and ClaSS S ceee 122 Designing the user interface 125 De SIQNING MENUS eee cece eeeee cence eeeeeteeeeeeeeeeeeaeeseaeeeeeeneeee 126 ACCESSING datas iriri sioe riitit re r a at raain 126 Coding application logic 2 0 eee eeseeeeseeeeeneeeeneeeeneeeeneees 127 Building distributed and Web applications that use EJB Server 128 About EJB Server ssssessesssesrresrrerrrerensennsrnnsrnnrrnnsransrneenrane 128 Contents Architecture of distributed and Web applications 129 Building EJB Server components with Powerd s es 130 Building a Java client for a distributed or Web application 136 Building client server applications using JDBC sesse 137 Building the application 0 0 eee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 138 Building Enterprise JavaBeans 1 1 component 00 141 PART 3 INFORMATION FOR ADMINISTRATORS CHAPTER 10 Configuring EJB Server ccsseccceseceesseeeeseeeseseeeeeeseeessseeeesenees 145 Configuring an EJB Server cee eeeeeeseeeneeeeeeeeeeeeeeeeeeeneeeeeees 145 General maneire e a e et deel eh 146 LOOM Tra Ona e aee ee eh aeaa
106. eeeeeeeeseeenenees 93 Configuring package properties eee eeee eee eeeeeeeeeeeeeneeeeeneeees 94 Exporting packages to EJB JAR files 95 CHAPTER 7 Creating Enterprise JavaBean Clients ccssccssceessseeneeeeeees 97 Developing an EJB client eee eee eeeeeeeneeeeeeeeseeeeseeeeeeeeeeneeeeaes 97 Generating EJB Stubs eee eesee cence esses eeeneeeeaeeeeaeeeeneeeeeneees 98 JaVat Packages 62 0 4 eat tee ee ee eae 99 Compiling Stubs ciei eaa a a et eden 99 Instantiating home interface proxies seesseeseereeereererrerereees 100 Obtaining an initial naming context 0 ee eeeeeeeeeee 100 Resolving Bean home names eeseeereererrrereereereere 103 Instantiating remote interface proxies s 104 Calling remote interface methods 000 ee eeeeeeeneeeeneeeeneeeeneees 106 Managing transactions 0 eee eeeeeeeeeeeeeeeeeeeeteeeeteeaeeseeeeenees 106 Serializing and deserializing Bean proxies 107 CHAPTER 8 Managing Persistent Component State ccsssssseeeeeees 109 Persistence for entity Java Beans 109 Using component managed persistence 110 Using automatic persistence 0 0 ee eeseeeeeeeneeeeeeeeeeeee 110 Persistence for stateful Component ecceeseeeeeeeeeeeeeeeneeeeaes 114 Using Java Serialization cece eeeeeeneeeeneeeeseeeeseeeeeeeeees 115 Using automatic persistence 0 0 eeseeeneeeneeeeeeeeeeeeees 115 Storage COMPONENMS eee eeeeeeeeeeeeseeeeeneeeeaeeceaeeseeeseeeeeeeae
107. eferred code base is SYBASE SYBASE_EJB java classes For security reasons it is preferable to deploy Java components to the SYBASE SYBASE_EJB java classes subdirectory or some other directory that is not accessible to HTTP downloads Deploying to this directory also allows your component to be refreshed and allows you to deploy classes in JAR files without reconfiguring the server s CLASSPATH environment variable If you deploy to another location make sure it is listed in the server s CLASSPATH environment variable 2 Use the Adaptive Server plug in to configure the component s custom class list specifying the classes that must be loaded when your component is loaded or reloaded as described in The custom class list on page 93 3 Use the Adaptive Server plug in to refresh the component by highlighting its icon and choosing View Refresh All You can also refresh the component by refreshing the package application or server where it is installed CHAPTER 6 Working with EJB Packages and Components The custom class list To support component refresh you must specify the custom class list to be loaded when a component is refreshed in the com sybase jaguar component java classes on page 85 component property This property must be set on the Properties tab in the Component Properties dialog box com sybase jaguar component java classes on page 85 describes the syntax of this property The custom class lis
108. elationships in a poster format Available only in print version Error Messages and Troubleshooting Guide explains how to resolve frequently occurring error messages and describes solutions to system problems frequently encountered by users Component Integration Services User s Guide explains how to use the Adaptive Server Component Integration Services feature to connect remote Sybase and non Sybase databases Java in Adaptive Server Enterprise describes how to install and use Java classes as datatypes functions and stored procedures in the Adaptive Server database xi Other sources of information xii Using Sybase Failover in a High Availability System provides instructions for using Sybase s Failover to configure an Adaptive Server as a companion server in a high availability system Using Adaptive Server Distributed Transaction Management Features explains how to configure use and troubleshoot Adaptive Server DTM features in distributed transaction processing environments XA Interface Integration Guide for CICS Encina and TUXEDO provides instructions for using Sybase s DTM XA interface with X Open XA transaction managers Glossary defines technical terms used in the Adaptive Server documentation Sybase jConnect for JDBC Programmer s Reference describes the jConnect for JDBC product and explains how to use it to access data stored in relational database management systems
109. en using automatic persistence EJB Server manages all interaction with the database There are two options for database storage when using automatic persistence 110 CHAPTER 8 Managing Persistent Component State Using mapped fields In the mapped table model you define a mapping from a database table to fields in your component implementation class When a write to the database is required EJB Server reads the field values after reading new data from the database EJB Server assigns new field values for each mapped database column This model corresponds to the Container Managed Persistence model required by the EJB 1 1 specification Using binary storage In this model you define state accessor methods and an IDL state type EJB Server calls your state accessor methods before writing data to the database and after reading from the database The state data is stored in an encoded binary form Because the relational data is encoded this model does not support finder methods other than findByPrimaryKey Identifying the storage technique The component uses mapped field storage if the value of the Table field on the Persistence tab begins with map for example map MyTable To configure automatic persistence 1 Configure Persistence tab properties 2 Specify field to column mapping properties 3 Specify finder method queries Configure Persistence tab properties Display the Component Properties window in the
110. ent control Specifies the name of the IDL control interface The control interface defines methods called by the EJB Server in response to changes in the instance lifecycle The choices are summarized in this table Control Interface Description JaguarEJB EntityBean For EJB entity Beans JaguarEJB StatefulSessionBean For EJB stateful session Beans JaguarEJB StatelessSessionBean For EJB stateless session Beans Generating stubs and skeletons You must generate stubs and skeletons for a Bean before it can run 86 To generate stubs and skeletons for a component Bean 1 2 Highlight the component icon Choose File Generate Stubs Skeletons The stubs and skeletons dialog box opens Select Generate Skeleton Enter a code base for the generated files Sybase recommends the SYBASE SYBASE_EJB java classes subdirectory Click OK CHAPTER 6 Working with EJB Packages and Components Creating Enterprise JavaBeans In most cases it is easiest to define a Bean using one of the import methods described in Importing Enterprise JavaBeans on page 71 However if you prefer editing IDL to Java you may follow the technique described here Creating a new EJB component from scratch Follow this procedure to create a new EJB component and define the home and remote interface 1 Double click the Installed Packages folder that will contain the Enterprise JavaBean 2 Select the Add new component icon in the r
111. ent support Components are reusable modules of code that combine related tasks methods into a well defined interface EJB Server components are installed on an EJB Server and contain the methods that execute business logic and access data sources You or your administrator install the component s executable code on the EJB Server Components can be distributed to Adaptive Server databases residing on the same host Once installed components can be used by any number of independent applications Since EJB Server components reside on the server components do not contain methods to display graphics or user interfaces that is EJB Server components are inherently nonvisual User interface developers or other component developers can browse a component s interface in the Adaptive Server plug in for Sybase Central in their code they use a client stub or proxy to invoke the component s methods The stub or proxy acts as a local surrogate for the remote component providing the same method signatures as the component and hiding the details of server communication EJB Server s server side component support and client side stub or proxy support are independent Any EJB Server client can execute any component Additionally since EJB Server uses standard CORBA IIOP as its core network protocol you can use CORBA client runtimes from other vendors to invoke components installed on an EJB Server All clients and components share a common in
112. entation recognizes the properties in the properties following table You can create multiple contexts with different properties For example you might create one context for proxies that connect with plain IIOP and another for proxies that connect using SSL 101 Instantiating home interface proxies Table 7 2 Sybase EJB 1 1 InitialContext Properties Property name java naming factory initial Description Specifies the fully qualified Java class name of the class that returns javax naming nitialContext instances that interact with the naming provider Use com sybase ejb InitialContextFactory for EJB Server clients java naming provider url Specifies the URL to connect to the EJB name server Set the value to a URL with the following format iiop hostname iiop port initial context where e hostname is the host machine name for the EJB Server that serves as the name server for your application If omitted the default is localhost e iiop port is the IIOP port number for the server e initial context is the initial naming context This can be used to set a default prefix for name resolution For example if you specify USA Sybase all names that you resolve with the context are assumed to be relative to this location in the name hierarchy When specifying the initial context the trailing slash is optional it is added automatically if you do not specify an initial context that ends with a slash If
113. er icon varbinary 1024 The type name is used during automatic table creation This feature is useful when a Java type can map to multiple SQL types in that case EJB Server defaults to the type with minimal storage requirements when creating the table Varchar columns default to 100 bytes length and varbinary columns default to 255 bytes Specify a type name to override the default Specify finder method queries Each finder method in the component s home interface requires a database query to select a set of primary keys For example the findByPrimaryKey method selects the key that matches the input parameter A findAll method might return all keys in the table EJB Server can correctly infer the query required to execute the findByPrimaryKey method For other finder methods you must enter properties to specify the query Display the All Properties tab and define new properties for each finder method Name each property mapQuery method where method is the finder method name For the value enter a query to select primary key values with a filter appropriate for the semantics of the finder method You can use the following placeholders to represent column and table names and parameter values Placeholder To indicate key The table s primary key which can consist of multiple columns table The name of the table 113 Persistence for stateful components Placeholder To indicate param Reference the valu
114. er From the client s view entity Beans persist as long as the associated database row has not been deleted EJB components use standard javax ejb APIs for component lifecycle and transaction control The Enterprise JavaBeans model allow you to use the EJB Server connection caching transaction management and lifecycle control features There are some restrictions to keep in mind for components They include e Parameters for methods in an EJB Server component must have datatypes that can be defined with CORBA IDL e Classes and JavaBeans components must have a default constructor a constructor with zero parameters When you deploy the component to the EJB Server PowerJ warns you about classes and methods that don t conform CHAPTER 9 Developing Applications with PowerJ and EJB Server Implementing the component General procedure EJB Server services Creating and deploying an EJB Server component involves these main tasks 1 Define and implement the EJB component in PowerJ Create an EJB 1 1 target that defines the type of Bean the Java package and class names and the component s transactional attribute PowerJ generates skeleton implementations for the SessionBean or EntityBean s home interface remote interface and implementation class Provide signatures for business methods in the remote interface and for any required methods in the home interface and add code to implement these methods in the implementat
115. er Naming Services lt component gt is the name of the component being bound as displayed in the Adaptive Server plug in Note You can set the server properties to enable password protection for name binding on a EJB Server name server See Name binding password security on page 177 Name binding example To illustrate how an EJB Server name server uses the initial context to create name contexts for objects on multiple servers assume two EJB Servers e Server A contains package Pkg1 and components CompX and CompY You assign the server an initial context of us sybase serverA e Designate server B to be the name server for server A by specifying the URL for server B iiop myhost 9050 in its Naming Services properties When you start server A it connects to server B using the name server URL you entered in server A s Naming Service properties The name server gets the initial context for server A and binds each object installed on server A The resulting name contexts are based on server A s initial context the package name and the components in the package For this example the name server creates the following bindings us sybase serverA Pkg 1 CompX us sybase serverA Pkg 1 CompY Figure 11 1 illustrates the name binding process 169 How does the EJB Server naming service work Server A us sybase serverA Figure 11 1 Name binding process Bind us sybase serverA Pkg 1 CompX us sybase
116. er transaction Multiple updates are issued before calling completeWork or an update depends on the results of queries that were issued since the last call to completeWork Applicable transaction attributes Requires Transaction or Requires New Transaction Updates from your component are performed by a single database update the update logic is independent of any other query issued by the method and you call completeWork in each method that issues an update In other words your component s updates are already atomic Supports Transaction Your component s methods make intercomponent method calls and the work done by called components must be included in one transaction Requires Transaction or Requires New Transaction Methods in the component interact with more than one database and updates to different databases must be grouped in the same transaction this also requires a transaction coordinator that supports two phase commit to those databases Requires Transaction or Requires New Transaction Transactions begun by your component must not be affected by the outcome of transactions begun by other components that call your component Requires New Transaction Work done by your component must never be done as part of a transaction Not Supported For example in the scenario illustrated in A transaction involving multiple components on page 56 the Enrollment component must be ma
117. es explicitly you can set the component s Automatic demarcation deactivation property in the Adaptive Server plug in This setting is appropriate if every method in your component executes a complete unit of transactional work in other words the transactional outcome is never pending when a method returns When this option is enabled EJB Server deactivates the component instance after every method invocation Upon deactivation the transaction is always committed unless the component aborts the transaction by calling the rollbackWork transaction primitive In the Adaptive Server plug in the Automatic demarcation deactivation property is set in the Component Properties window beneath the Transactions tab Configuring component properties on page 75 describes how to view and modify component properties in the Adaptive Server plug in For any component transactional or not you must decide how your component s instance lifecycle will be managed Component lifecycles on page 51 describes the general instance lifecycle model and your options for instance lifecycle management Define the component in the Adaptive Server plug in Use the Adaptive Server plug in to define the components If you have already created Java components you can import the component interfaces into the Adaptive Server plug in you do not need to define method prototypes again in the Adaptive Server plug in Connection caching increases the scalability of
118. es the JavaSoft EJB javax ejb classes and EJB Server s EJB stubs to call EJB Server component methods This client model follows the EJB 1 1 Specification Chapter 7 Creating Enterprise JavaBean Clients describes how to implement EJB clients Network protocol support EJB Server supports the following protocols Internet Inter ORB Protocol IIOP IIOP is the standard protocol for communication between CORBA ORBs over TCP IP networks The EJB client model uses IIOP IIOP connections can also be tunnelled inside of HTTP to allow connections through firewalls that do not allow passage of IIOP traffic as discussed in HTTP tunneling support on page 9 Hypertext Transfer Protocol HTTP HTTP is used by Web browsers for file downloads and uploads EJB Server provides HTTP support to allow you to deploy HTML pages and Java applets on the EJB Server itself To enable support for IIOP you must define a listener in the Adaptive Server plug in The listener configuration specifies a server address host name and port number as well as the network protocol and security settings to be used by clients that connect to that listener CHAPTER 1 About EJB Server To enable support for HTTP you must use the standard configuration and port number HTTP tunneling support Almost all network firewalls allow HTTP traffic to pass but some reject IIOP packets When IIOP traffic is tunnelled inside of HTTP your clients can connect to
119. escribes basic configuration tasks that you can perform to customize your installation such as replacing an EJB Server changing server properties and defining new connection caches The EJB Server runtime environment is preconfigured With minimum setup you can have a fully functioning EJB Server Although the default settings are usually sufficient EJB Server provides you with the flexibility to customize your server environment when necessary You can perform all configuration tasks using the Adaptive Server plug in For instructions for starting Sybase Central and the Adaptive Server plug in and for starting and enabling EJB Server refer to task descriptions in Chapter 2 Getting Started Topic Page Configuring an EJB Server o hs Configuring server stack size 151 Character sets 152 Shared memory connections 152 Managing connection caches 153 Managing XA resources 159 Configuring listeners 163 Replacing an EJB Server 165 Configuring an EJB Server To configure or modify the properties of an individual EJB Server 1 From within the Adaptive Server plug in display the EJB Server you want to configure by double clicking the host Adaptive Server icon and then double clicking the Enterprise JavaBeans folder 2 Highlight the EJB Server 145 Configuring an EJB Server 3 Select File Properties You see the Server Properties window which contains these tabs e General define general
120. et proxy support Adaptive Server Enterprise allows a user to assume the identity and privileges of another user This feature can be used with any database that recognizes the command set session authorization login name When proxy support is enabled connections retrieved from the cache are set to act as a proxy for the username associated with the EJB Server client To set proxy to another user name use the Java JCMCache getProxyConnection method in your component Set proxy support must be enabled in the cache properties file before components can take advantage of it To enable set proxy support add the following line to the cache properties file com sybase jaguar conncache ssa true To disable support delete this line or change t rue to false Connection cache refresh If you have just installed the cache in a server or modified an installed cache refresh the server or the connection cache before you attempt to test the cache You can refresh as follows e To refresh the cache 157 Managing connection caches a Highlight the Installed Connection Caches folder under the server icon where the cache is installed b Select View Refresh Folder e To refresh the server highlight the server icon where the cache is installed then choose View Refresh All All caches installed in the server will be refreshed Refreshing a cache may affect running components that are using the cache specifically e
121. euse of resources and minimize the possibility that a client application can monopolize a server resource The component lifecycle and the transaction model are tightly integrated You must understand both to use transactions effectively in your application Topic Page Component lifecycles 51 The EJB Server transaction processing model 55 OTS XA transaction model 66 Component lifecycles The EJB Server component lifecycle is designed to e Maximize sharing and reuse of server resources e Minimize the possibility that a client application can monopolize server resources To achieve these goals EJB Server supports the concepts of component instance pooling and early deactivation 51 Component lifecycles States in the component lifecycle 52 Instance pooling allows a single component instance to service multiple clients The component lifecycle contains activation and deactivation steps Activation binds an instance to an individual client deactivation indicates that the instance is unbound Instance pooling eliminates resource drain from repeated allocation of component instances Early deactivation allows a component s methods to specify when deactivation occurs Early deactivation prevents a client application from tying up the resources that are associated with a component instance and allows the instance to serve more clients in a given time frame A component that is deactivated after each method call and
122. face 138 JDBC Java client server applications 137 L LDAP server 177 lifecycles component states in 52 of components in general 51 listeners configuring 8 163 creating 164 default host name 163 deleting 164 modifying 164 preconfigured 163 properties 164 localhost default listener settings 163 managing connection caches 153 managing XA resources 159 mapping roles 94 menus PowerJ 126 method restarting after modifying 146 155 middle tier servers see EJB Server modifying listeners 164 multitier application development overview 19 N name binding 169 naming conventions for Java stub files 99 naming services about 167 explanation of 12 initial context 168 LDAP server 177 name binding 169 password 177 persistent storage 170 support for 12 transient storage 170 network addresses 8 protocols 8 number of user connections parameter 152 Index O object oriented programming PowerJ 15 OTS XA transaction options 58 overview EJB Server features 1 multitier application development 19 P package restarting after modifying 155 package EJB Server definition 18 installing components in 75 modifying 93 properties of 94 refreshing after modifying 10 restarting after modifying 146 usesof 10 package Java for generated stub classes 99 parentheses in SQL statements xv persistence container managed 110 for entity components 109 for stateful components 114 of component state 109 persistent s
123. from the drop down list This is the role from which the J2EE role inherits its permissions and members 5 Repeat steps 2 through 4 for each method in the package with an encoded J2EE role All Properties settings The All Properties tab allows you to edit package property settings as they are stored in the EJB Server configuration repository You can only delete properties that you have added you cannot delete default properties such as the com sybase jaguar package components property To edit package properties 1 Look for the property name in the list of properties If it is displayed highlight the property and click Modify Otherwise click Add 2 If adding the property fill in the Add Property fields as follows e Enter the property name in the Name field e Enter the value in the Value field 3 If modifying a property edit the displayed value in the Modify Property window Exporting packages to EJB JAR files You can create an EJB JAR file that contains the Java classes and deployment descriptors for the EJB components installed in an EJB Server package The JAR file can be deployed to another EJB Server or any EJB compatible server Exporting JAR files requires the Java Development Kit JDK version 1 2 2 The EJB Server installation enables the JDK for exporting packages See the installation guide for your platform for information Exporting an EJB JAR file 1 Inthe Installed Packages folder highlight the package to
124. g with find Every entity Bean must have a findByPrimaryKey method that matches the following pattern remote interface findByPrimaryKey in pk type primaryKey raises CtsComponents FinderException where remote interface is the IDL remote interface and pk type is the IDL type of the primary key Entity Beans can have additional finder methods of two types e Those that return a single remote interface instance and raise CtsComponents FinderException as shown in the pattern below remote interface findSuffix in parameters raises CtsComponents FinderException where remote interface is the IDL remote interface Suffix is a name suffix other than ByPrimaryKey and in parameters is a valid parameter list composed solely of in parameters e Those that return a sequence of instances whose primary keys match a specified search criteria The pattern is componentList findSuffix in parameters raises CtsComponents FinderException where component is the component name Suffix is a name suffix other than ByPrimaryKey and in parameters is a valid parameter list composed solely of in parameters CHAPTER 6 Working with EJB Packages and Components Defining remote interface methods Sequence types are automatically generated The Adaptive Server plug in creates IDL typedefs defining a sequence of remote interface methods and a sequence of primary keys when you set the Primary Key field on
125. h Tools Debug Run View Window Help anaana SBAx Mo 6 6 6 r r r r r kd kd kd r kd cooo eere Imports E 4 custom imports for SlEjbClient1lFrame add your custom import statements here lass SlEjbClientiFrame extends java awt Frame implements ja public SlEjbClient1iFrame i super public void processEvent java awt AWTEvent defaultProcessEvent event private void unhandledEvent String listenerName String i public java awt Container getContentPane Use the following if you inherit from a JFC cont _ return super getContentPane Ma E Ln 4 Col 1 CHAPTER 9 Developing Applications with PowerJ and EJB Server Designing the user interface You create the user interface in a PowerJ form A form is an application window on which you place buttons text boxes and other elements of the user interface ky ContactMaintenanceClient Any program with a graphical user interface has a main form which is the first window displayed by the application When you create an applet or application target a main form is created for you Your application may require additional forms which you can add by selecting File New from the menu bar or clicking the corresponding toolbar button Construct the user interface by selecting components on the component palette and dropping them onto the form In the code editor for the class you write cod
126. h your session with the component Call the getHandle method on the remote interface which returns a javax ejb Handle instance You can serialize the Handle instance using the standard Java serialization protocol as shown in the example below String _serializeTo Name of file to save to Statefull proxy Active proxy instance try System out printin Serializing to _serializeTo Handle handle proxy getHandle FileOutputStream ostream new FileOutputStream _serializeTo ObjectOutputStream p new ObjectOutputStream ostream p writeObject handle p flush ostream close catch Exception e System out printin Serialization failed Exception e toString e printStackTrace return Use the standard Java deserialization protocol to extract the Handle instance then call getEJBObject to restore the proxy as shown in the example below 107 Serializing and deserializing Bean proxies String _serializeFrom Name of file to read from Statefull proxy try System out printin Deserializing proxy from _serializeFrom FileInputStream istream new FileInputStream _serializeFrom ObjectInputStream p new ObjectInputStream istream Handle handle Handle p readObject proxy statefull handle getEJBObject istream close catch Exception e System out println Deserialization failed Exception e toString e prin
127. han in the dbname table Time Out This setting is reserved for future use 83 Configuring component properties All Properties tab 84 Field Description Time Stamp When using a mapped database table specifies the timestamp used for optimistic concurrency control Specify one of the following Acolumnname The name ofa column in the mapped table that is incremented in each update By default EJB Server uses 4 byte integer timestamp You can also use a 16 byte binary value but to do so you must set the com sybase jaguar component ts length property to binary 16 e None Enter none to disable optimistic concurrency control This setting is not recommended e Novalue Ifyou leave the Time Stamp field blank EJB Server uses all column values to perform optimistic concurrency control For best performance use a 4 byte integer timestamp column The timestamp column need not be mapped to the component s persistent state fields 16 byte binary timestamp values are not usable when other processes besides EJB Server update a table The All Properties tab allows you to edit component property settings as they are stored in the EJB Server configuration repository You can only modify or delete properties that you have added you cannot modify or delete default properties such as the Instance Timeout property To add a property 1 Fill in the Add fields as follows a Enter the property
128. hat can be deployed directly to EJB Server Deploy Java nonvisual objects to the Sybase Java VM running in an Adaptive Server database Retrieve and update database information using Sybase s patented DataWindow technology Access a variety of industry standard databases through JDBC the Java standard for database access Build windows menus and other user interface components using visual programming tools CHAPTER 2 Getting Started This chapter provides basic concepts terminology and the task information you need to get started using EJB Server Topic Page Before you use EJB Server 17 Terminology and concepts 18 Basic tasks 25 Note Your installation must have a valid license for Adaptive Server EJB Server to use this product You can perform all the tasks necessary to use EJB Server from the Sybase Central the graphics based management tool for Sybase products This chapter presents a conceptual overview of the processes you will use to develop EJB Server applications Refer to Chapter 6 Working with EJB Packages and Components to create EJB component applications The installation process starts and preconfigures your Adaptive Server host your EJB server and Sybase Central This chapter provides directions for enabling the EJB Server option starting and stopping EJB Server and setting up the Adaptive Server plug in to Sybase Central Refer to Chapter 10 Configuring EJB Server for other
129. hat has a pending transaction the EJB component s work is performed outside the existing transaction Since entity Beans are almost always involved in transactions this value is not usually used for an entity Bean Supports The EJB component can execute in the context of an EJB Server transaction but a transaction is not required to execute the component s methods If a method is called by a base client that has a pending transaction the method s database work occurs in the scope of the client s transaction Otherwise the EJB component s database work is done outside of any transaction Required The EJB component always executes in a transaction Use this option when your EJB component s database activity needs to be coordinated with other components so that all components participate in the same transaction Requires New Whenever the EJB component is instantiated a new transaction begins Mandatory EJB component methods must be called in the context of a pending transaction If a client calls a method without an open transaction the EJB Server ORB throws an exception Never The component s methods never execute as part of a transaction and the component may cannot be called in the context of a transaction If a client or another component calls the component with an outstanding transaction EJB Server throws an exception Bean Managed For EJB session Beans only The EJB comp
130. ializable Java class for example foo bar MyPK The IDL string type Use string if the key relation has only a string column In Java the mapped primary key is java lang String You can add methods to a home interface using a text editor However the method signatures in a home interface must follow the design patterns described here to ensure that the generated code works as intended Patterns for create methods All Beans can have create methods which clients call to instantiate proxies for session Beans and insert new data for entity Beans Create methods must return the Bean s IDL remote interface type and raise CtsComponents CreateException Create methods can take any number of in parameters To distinguish multiple overloaded create methods append two underscores and a unique suffix This is the standard Java to IDL mapping for overloaded method names When generating stubs for Java EJB Server removes the underscores and suffix from the stub method name The pattern is as shown below remote interface creat 89 Creating Enterprise JavaBeans 90 in parameters raises CtsComponents CreateException remote interface create__suffixl in parameters raises CtsComponents CreateException Patterns for finder methods Only entity Beans can have finder methods Clients call finder methods to look up entity instances for existing database rows Names of finder methods typically have names beginnin
131. ight window The Component wizard displays 3 In the Add Component dialog box select the Define New Component check box and click Next 4 Inthe Name of Component dialog box enter a name for the component and click Next 5 Inthe Summary Page click Finish to create the object 6 Display the Component Properties dialog box Make the following changes on the General tab a Set the Component Type to correspond to one of the following values Component Type To indicate EJB Entity Bean An entity Bean EJB Stateful Session Bean A stateful session Bean EJB Stateless Session Bean A stateless session Bean b Inthe Class Type field enter the name of the Java class that will implement your Bean for example foo bar MyBeanImpl Note The Home Interface Class Remote Interface Class and Primary Key Class fields cannot be edited These fields are set automatically after the Bean s IDL interfaces and datatypes have been defined You can change them by changing the component s IDL interfaces and types in subsequent steps 87 Creating Enterprise JavaBeans 88 10 11 12 13 14 15 If you are defining a stateful session Bean optionally switch to the Persistence tab and enter a time limit in the Time Out field This value specifies how long in seconds that a client can hold an instance reference without making any calls If you do not enter a value or you specify 0 client references do not
132. individual server properties e Naming Service set the EJB Server naming service options e All Properties edit server property settings in their raw format that is as they are stored in the configuration repository Saving property changes and refreshing the server If you modify any property click OK in the Server Properties window to save your changes or click Cancel to disregard the changes When you modify server properties you must refresh the server for the changes to take effect To refresh the server select View Refresh All General Table 10 1describes the general properties that you can configure for individual servers 146 Chapter 10 Configuring EJB Server Log Trace Table 10 1 Server general properties Property Description Comments Charset Specify the character set used by the By default the server server Make sure that the character set uses iso_I in the EJB Server is the same as that used in Adaptive Server Description Enter a description of the server up to 255 characters in length Classpath Displays the contents of the server s The field is read only CLASSPATH environment variable This setting specifies the directories from which Java class files can be loaded It is defined by the start up script when you start the server and helpful for debugging various errors Tracing provides information about activities carried out by your application Trace output is sen
133. ing the database server handle concurrency issues The component s transactional semantics may affect the interaction with the database EJB Server methods can return tabular data to the calling client This feature can be useful for the following reasons Use with data aware controls Some front end tools provide objects that can automatically display a result set For example in a PowerJ application you can pass the result set obtained from an EJB Server method invocation to a PowerJ Query object or DataWindow and it will display the rows Efficiency For tasks that require returning tabular data using an EJB Server result set is the most efficient alternative Common uses of result sets include menu and pick list population For example in an online clothing catalog you need to list in stock sizes for each item CHAPTER 1 About EJB Server The EJB Server result set allows data to be sent all at once rather than requiring a get next row method and one client server round trip per method A large EJB Server result set can be sent with less overhead than is required to encapsulate tabular data as an object and send a serialized version of the object to the client Each component model provides an interface that allows you to define result sets from scratch or to forward results from a database query directly to the client Permissions and roles EJB Server and its host Adaptive Server share user names and roles If you creat
134. ion CHAPTER 9 Developing Applications with PowerJ and EJB Server Attribute Description Requires New Whenever the component is instantiated a new transaction begins Transaction Supports The component can execute in the context of an EJB Server Transaction transaction but a transaction is not required to execute the component s methods If a method is called by a base client that has a pending transaction the method s database work occurs in the scope of the client s transaction Otherwise the component s database work is done outside of any transaction Not Supported The component s methods never execute as part of a transaction If the component is activated by a client that has a pending transaction the component s work is performed outside the existing transaction Mandatory Component methods must be called in the context of a pending transaction If a client calls a method without an open transaction the EJB Server ORB throws an exception Bean For EJB session Beans only The component can explicitly begin Managed commit and rollback new independent transactions by using the javax transaction UserTransaction interface Transactions begun by the component execute independently of the client s transaction If the component has not begun a transaction the component s database work is performed independently of any EJB Server transaction Influencing transaction outcome If your componen
135. ion class Set the deployment options for your component including the EJB Server package name and EJB Server component name Deploy to EJB Server so you can test the component This is an iterative process deploy test debug and redeploy PowerJ supports in process debugging of EJB Server components For more information about debugging Java components running in EJB Server see the PowerJ documentation When designing the component you can take advantage of these EJB Server services to enhance your application s performance Transaction management Database access and result set management Connection caching Instance pooling These EJB Server features enable you to write high performance applications with effective error management You need to set deployment options in PowerJ to enable some of these features in your component and your component needs to call methods that allow it to cooperate with other components 131 Building distributed and Web applications that use EJB Server Transaction management How it works When a component is transactional and uses the EJB Server connection management feature commands sent to a data source are automatically performed as part of a transaction Component methods can call EJB Server s transaction state primitives to influence whether EJB Server commits or aborts the current transaction The EJB Server coordinates the database activity of all transactional components
136. ions for shared memory See the System Administration Guide for more information Chapter 10 Configuring EJB Server Managing connection caches A connection cache maintains a pool of available connections that EJB Server components use to interact with the data server You must configure connection caches for the specific user database combinations used by your components A connection cache entry improves performance by eliminating the overhead associated with setting up a connection when one is required Note You must install caches in an EJB Server before components in that server can access the cache You must refresh the cache or refresh the server using View Refresh All or restart the server before any changes to the list of installed caches or to cache properties take effect Creating and installing a new connection cache To create a new connection cache and add it to an EJB Server 1 Double click the EJB Server icon 2 Double click the Installed Connection Caches folder 3 Double click the Add new connection cache icon in the right side of the window 4 Follow directions in the Add Connection Cache wizard You will enter e The connection cache name e An optional description of the cache e The JDBC driver name e The server name which is the URL appropriate for JDBC calls e The user name for the cache e The user password for the cache 5 Configure the connection cache properties as described in General tab co
137. ise JavaBeans Deploying component classes 92 If you are creating components from scratch in the Adaptive Server plug in to Sybase Central you must follow the steps in this section to deploy the component class and other classes that it depends on If you deploy from PowerJ PowerJ performs these steps for you If you are using another EJB development tool that can export EJB JAR files import the EJB JAR file as described in Importing Enterprise JavaBeans on page 71 If you import an EJB JAR file that calls EJB Server components that are not implemented in the same JAR file you must list the stub classes for the called components in the custom class list as described below EJB Server supports hot refresh of components by using a Java class loader This feature speeds the development process by allowing you to deploy new class versions without restarting EJB Server Repeat the steps below to deploy new versions of your implementation To deploy EJB component classes 1 Deploy the component class files stub and skeleton files and other classes required by the implementation to EJB Server For example you may need to copy stubs for user defined types and utility classes that are in your component s package If deploying class files place each class in their respective SYBASE SYBASE_EJB java classes package subdirectories If deploying a JAR file place it in the SYBASE SYBASE_EJB java classes subdirectory The pr
138. it of deployment Using the Adaptive Server plug in you can import and export archived copies of the components in a package and related application files They allow you to control which users can access the components Packages form one level in the EJB Server authorization hierarchy A package is not available to the user unless it is deployed to the EJB Server s Installed Packages folder The Adaptive Server plug in allows you to map roles through each package for methods within the package See Configuring package properties on page 94 for information about mapping roles When EJB Server is installed the AseAuth default package is deployed automatically to EJB Server You will see this package in the Installed Packages folder AseAuth contains information you need to log in to EJB Server from the Adaptive Server plug in Do not alter or delete this package CHAPTER 6 Working with EJB Packages and Components Importing Enterprise JavaBeans Importing EJBs from an EJB JAR file This section describes how you import Enterprise JavaBeans These are the usual methods you will use with EJB Server See Creating Enterprise JavaBeans on page 87 for directions for creating JavaBeans from scratch The Adaptive Server plug in to Sybase Central supports two methods of importing Enterprise JavaBeans e From an EJB JAR file An EJB JAR file contains the implementation classes interface classes and deployment descriptor for one
139. le in the target is a Java class You can expand the targets in the left pane of the Workspace view to show classes as well as the properties methods and data members of individual classes A pop up menu lets you add new properties methods and events In the right pane you can further define your classes and attributes and view and edit Java code Views olx File Edit View Go Tools Window Help 2 e ees Targets And Files SIEjbClient1 Frame My Workspace SLEJBClient1 H 6 ClientBean JDK 1 1 or later Classes ustom imports for S1EjbClient1Fraj H A ClientBeanAll ava JAR B SlEjbClient1 JDK 1 1 or later Applicati E a SIEjbClient1 E amp es SIE bClienti Frame la lEjbClient1Frame extend C Imports C Data Members public S1EjbClient1Frane getContentPane processE vent ijava awt AWTE super SIEjbClient1 Frame cb_1_actionPerformed SIEjbClient1 Frame_windowCl unhandledE vent String listene s gt a Objects Intetnationalization SIEjbClient Frame add your custom import statements public void processEvent java awt 123 About the development process Writing code 124 From the Workspace view you can use the code page or open the code editor for a class or an individual method or event In the editor options you can choose to view all the code for the class or one method at a time You can hide or view the code that PowerJ generates 24 SIEjbClient1 Frame olx File Edit Searc
140. logy and concepts To create and deploy an EJB Server application 1 Define packages components and methods The Adaptive Server plug in for Sybase Central is the EJB Server GUI interface It allows you to easily define the packages components and methods that EJB Server clients use to run an application The Adaptive Server plug in for Sybase Central generates The client side stub files Stubs contain interface information used by the client to invoke EJB component methods e The server side skeleton files Skeletons provide the interface information of each component method 2 Create the applets and components Once you have generated the stubs and skeletons write the Java classes that once linked with the stub files form the basis of your downloadable applet In addition to the applet you need to develop the server side components that link with the skeletons to form the business logic of your servlet EJB Server supports many of the integrated development environment IDE tools such as PowerJ available today 3 Deploy the application You register components on the EJB Server Since EJB Server is also a Web server you can write an HTML page for your applet and install it on EJB Server The EJB Server runtime environment A typical EJB Server application has an applet or HTML page associated with it Once you build and deploy such an application it runs in the following fashion 1 EJB Server receives an HTTP
141. mation see Building Internet and Enterprise Applications in the Enterprise Application Studio online books collection Interface definitions can be imported from existing Java classes or from standard CORBA IDL files The Adaptive Server plug in also generates stub classes for use in Java client applications Features Deployment support Hot refresh support To simplify application deployment the Adaptive Server plug in defines the following basic middle tier application units e Servers A server represents one EJB Server runtime process Each server has its own network addresses for client session connections and for HTTP HTML connections All servers on one host machine share the same configuration repository For administration purposes you can connect to any server on the host machine to configure other servers on the same host e Packages A package organizes components into cohesive secure units that can be easily deployed on another EJB Server Packages can be exported or saved as a Java archive JAR file The package archive includes the definition of all components in a package plus any supporting files such as source code and client files that you specify Package archives exported from one server can easily be imported for redeployment on another server Note Do not confuse EJB Server package names with Java package names e Components A component definition consists of the component s method sign
142. me space when packages and components are added or deleted in the Adaptive Server plug in EJB Server provides industry standard client side APIs for naming services EJB Server also provides implementations of the CORBA standard CosNaming API and the Java Naming and Directory JNDI API SeeChapter 7 Creating Enterprise JavaBean Clients for more information Connection caching Connection caching allows EJB Server components to share pools of preallocated connections to the database server avoiding the overhead imposed when each instance of a component creates a separate connection Components that support transactions must use a connection from an EJB Server connection cache to interact with the database Transaction management EJB Server s transaction management feature allows you to specify a transaction coordinator and define a component s transactional semantics as part of the component interface Thread safety features Since EJB Server is a multithreaded environment component instances that share resources and volatile data must be coded or configured to avoid problems with inconsistent state For example if all instances of a component write to the same file you must take steps to ensure that the file is locked before each instance writes to it and unlocked when the write completes If writes to the file are allowed to occur simultaneously then output from two component instances may be mixed together
143. mpiled into binary files with the extension class The binary files contain bytecodes that can be interpreted by a Java VM These files are usually called class files Building distributed and Web applications that use EJB Server This section describes how to use PowerJ and EJB Server together to create distributed and Web applications About EJB Server What it is EJB Server is a component transaction server that hosts Java components Using PowerJ you can develop EJB Server Java components and Java client programs that connect to EJB Server and execute component methods When a client invokes a method on an EJB Server component EJB Server intercepts the call locates an instance of that component that can carry out the request passes the parameters and invokes the method then returns the result to the client EJB Server An EJB Server component is a reusable module of code that combines related components tasks into a well defined interface EJB Server components are installed on an EJB Server and contain methods that execute business logic and access data sources Components are nonvisual they do not display graphics or user interfaces You can import an EJB Server component into PowerJ and use the Reference Card to browse its methods and properties Data access To optimize database processing EJB Server provides support for connection caching Connection caching allows EJB Server components to share pools of preallocated conne
144. mponent Stateful versus stateless components 54 The EJB Server component lifecycle allows component instances to be recycled idle component instances can be cached when idle and bound to the service of individual clients only as needed If your component has been coded to support early deactivation a client holding a reference to the component s stub or proxy object may be serviced by several different instances of the component After each deactivation the next method invocation causes an instance to be activated and bound to the client Overall server scalability is increased because a new instance does not have to be instantiated each time a client invokes a method Instance pooling eliminates resource drain caused by repeated allocation of new component instances For Java components you can implement a lifecycle control interface to control whether the component instances are pooled These interfaces also provide activate and deactivate methods that are called to indicate state transitions in a component instance s lifetime For more information on these interfaces see the following sections e Java components can implement the interface jaguar beans enterprise ServerBean To support instance pooling code that responds to activation events must restore the component to its initial state that is as if it were newly created The Java interface has methods that allow an instance to selectively refuse pooling canReuse in J
145. n You can use a Java development tool such as Sybase PowerJ to define and develop Beans in the EJB 1 1 format and create an EJB JAR file The Adaptive Server plug in can read the JAR file and create a package containing a component for each Bean in the JAR file See Chapter 6 Working with EJB Packages and Components for more information about importing EJB JAR files CHAPTER 4 Creating Component Based Applications Developing clients You can use PowerJ to develop Java clients for EJB Server components Basic tasks for developing clients include e Generate EJB stubs e Add code to create the initial naming context and instantiate the home interface proxies e Add code to instantiate remote interface proxies e Add code to call remote interface methods See Chapter 7 Creating Enterprise JavaBean Clients for detailed information about developing clients 49 Deploying the application 50 CHAPTER 5 Understanding Transactions and Component Lifecycles This chapter explains the EJB Server component lifecycle and transaction processing models Transactions allow you to group database updates performed by multiple components into a single atomic unit of work which greatly simplifies error recovery in component based applications The component lifecycle determines how instances of a component are allocated bound to a client and destroyed The EJB Server component lifecycle is designed to maximize r
146. n EJB 1 1 JAR file to the repository 1 Start the Adaptive Server plug in if it is not already running and connect to the EJB Server where you want to install the component Double click the Installed EJB Packages folder Select File Deploy EJB 1 1 JAR The Deploy wizard displays If a package exists in your repository with the same name as the EJB JAR display name indicate whether the Adaptive Server plug in should prompt you before overwriting existing packages with the new definition Enter the path to the JAR file and click Next The Adaptive Server plug in creates a new package in the repository that contains a component for each Bean defined in the JAR file printing status messages and warnings to the Deploy Wizard The new package has the same name as the EJB JAR display name If there is no display name the new package has the same name as the JAR file For each Bean in the EJB JAR EJB Server creates an EJB component with the same name as the ejb name element in the EJB JAR deployment descriptor Home names for imported EJB components EJB Server sets an imported Bean s home name to the EJB Server default package component where package is the Adaptive Server plug in package name and component is the Adaptive Server plug in component name Installing a package in the Adaptive Server plug in 1 Double click the Installed EJB Packages folder Choose File Install Existing Packages The Select dialog b
147. n IIOP listener has not been configured the server attempts to open a listener at this address IIOP localhost 9000 Listener start up can fail if a port is already in use You can verify the listener addresses in use by viewing the initial log entries in the srv log file Configuring listeners This section describes how to create modify and delete a listener All of the configuration tasks require you to first access the Listeners folder from the Adaptive Server plug in 1 Double click the Adaptive Server icon 2 Double click the Enterprise Java Beans folder 3 Double click the EJB Server folder 4 Click the Listeners folder on the right side of the window 163 Managing XA resources Creating a new listener 1 Double click the Add new listener icon The Add new listener wizard displays 2 Add the name host name and port number for the listener in the Name and Description window Press Next See Table 10 6 3 Select the iiop http or tds protocol from the drop down menu on the Select Type of Protocol window Press Next 4 Verify the new listener on the Summary Page Window Press Finish The new listener appears on the right side of the window Modifying an existing listener 1 Highlight the listener you want to modify 2 Select File Properties 3 Make your modifications and click OK Listener properties are described in Table 10 6 Deleting a listener 1 Highlight the listener you want
148. n cache click OK to save your changes or click Cancel to disregard them You must refresh a newly installed cache for any changes to take effect and you should test the connection with Ping before trying to access it from components These operations are described in detail below You cannot define two distinct caches that use identical values for server user password and JDBC driver If two caches are defined with matching values for these settings and your application requests one EJB Server returns the first match that is found Chapter 10 Configuring EJB Server Saving property changes and refreshing the server If you modify any property click OK or Apply in the Connection Cache Properties sheet to save your changes or click Cancel to disregard the changes When you modify server properties you must refresh the server for the changes to take effect To refresh the server highlight the server icon and select View Refresh All General Select the General tab on the Connection Cache Properties window to set the basic connection cache options described in Table 10 3 From the General tab window you can test the cache configuration to verify that connections can be made using the options you supply See Connection cache ping on page 158 for more information Table 10 3 General tab connection cache properties Property Description Comments Example Connection The name for this cache Connection cache names are
149. n use this schema to represent the hierarchy of objects in the namespace for example by geographic region organizational unit and so on If you use an EJB Server as the name EJB Server server uses this format lt Level 1 gt lt Level 2 gt lt Level 3 gt The number of levels depends on the hierarchy you want to represent For example US sybase finance US sybase marketing US sybase sales If you use an LDAP server as an external naming service the initial context must follow the syntax and schema of the LDAP server LDAP servers have predefined schema for common objects such as country organization and organizational unit EJB Server uses the following format for an LDAP compatible initial context ou lt organizational unit gt o lt organization gt c lt country gt Using the previous examples the initial contexts would be ou finance o sybase c US ou marketing o sybase c US ou sales o sybase c US On start up the name server binds all object implementations on an EJB Server to the initial context of the server on which the object is installed Once the server binds an object the structure of the resulting name context is lt initial context gt lt package gt lt component gt where lt initial context gt is the initial context property for the server where the component is installed lt package gt is the name of the package being bound as displayed in the Adaptive Server plug in Chapter 11 EJB Serv
150. nal semantics You must decide what transactional semantics the component will follow and how the component lifecycle will be managed Chapter 5 Understanding Transactions and Component Lifecycles explains the design concepts for transaction and lifecycle control in EJB Server components The following design decisions determine how EJB Server manages your component s transactions e Which transaction attribute the component uses e Whether transaction boundaries are managed explicitly in the component implementation or implicitly by EJB Server If your component interacts with the database you must specify a transactional attribute that determines how the component s database work is grouped within EJB Server transactions If another component invokes your component the transaction attribute determines whether your component s database work is done independently or as part of the existing EJB Server transaction You must also decide whether or not you will code your component to manage transaction boundaries explicitly To manage transaction boundaries explicitly each method must call one of EJB Server s transaction state primitives to indicate the status of the component s transactional work Using transaction state primitives on page 61 describes this topic in detail 45 Implementing components and clients Define connection caches Implementing 46 Instead of writing code to manage transaction boundari
151. name in the Name field b Enter the value in the Value field 2 Click Add and then OK To delete a property 1 Highlight the property you want to delete 2 Click Delete and then OK The following component properties can be configured only from the All Properties tab CHAPTER 6 Working with EJB Packages and Components com sybase jaguar component keys For an EJB entity Bean specifies the name of an IDL typedef for a sequence of the Bean s primary key structures This type is used when generating the skeleton and implementation classes for the component When you manually specify a value for the Primary Key field on the Persistence tab EJB Server sets this property to module componentKeys where module is the module containing the primary key type and component is the component name The Adaptive Server plug in defines the type if it does not exist using the following structure typedef lt sequence pk gt componentKeys where pk is the primary key type and component is the component name Set the com sybase jaguar component keys property only when you have manually defined a sequence that uses another naming convention or that is located in another module If you have used PowerJ or the Adaptive Server plug in import feature to import an entity Bean the com sybase jaguar component keys typedef may use a different naming convention com sybase jaguar component tx_outcome Determines whether an exception is thrown to th
152. naming context used to resolve names to Bean proxies To obtain an initial naming context initialize a java util Properties instance and set the properties listed in Table 7 2 Pass the properties instance to the javax naming nitialContext constructor The code fragment below shows a typical call sequence import javax nam Ing static public Context getInitialContext throws Exception java util Properties p new java util Properties Sybase implementation of InitialContextFactory p put Contex URL for t p put Contex Username p put Contex p put Contex t INITIAL CONTI EXT_FACTORY com sybase ejb InitialContextFactory he Server s IIOP port t PROVIDER_URL iiop myhost 9000 pooh password is tigger2 ECURITY_PRINCIPAL pooh S S ct ct ECURITY_CREDENTIALS tigger2 Now create an InitialContext that uses the properties return new InitialContext p 100 CHAPTER 7 Creating Enterprise JavaBean Clients EJB servers from different vendors require different Initial Context property settings If you are creating a client application that must be portable to other EJB servers use an external mechanism to specify properties rather than hard coding values in the source code For example in a Java application use command line arguments or a serialized Java properties file Sybase InitialContext The Sybase InitialContext implem
153. nce the stub or proxy object exists all details of network communication are hidden from the application developer All stubs and proxies use the Inter ORB Invocation Protocol IIOP to communicate with the EJB Server See Network protocol support on page 8 discusses client protocols in detail For more information on stub and proxy objects see Chapter 7 Creating Enterprise JavaBean Clients In the simplest case of lifecycle management an instance is allocated for each stub or proxy created by the client and is destroyed when the client explicitly requests destruction or when it disconnects whichever happens first More sophisticated components can be coded to support instance pooling Instance pooling allows EJB Server to maintain a cache of component instances and bind them to client sessions on an as needed basis Instance pooling requires the following changes to your component e The component must provide activate and deactivate methods EJB Server calls the activate method just before an instance is bound to a client session activate must be able to reset the component to an as allocated state EJB Server calls deactivate just before an instance is unbound from a client session that is made idle again e Methods in the component must use the EJB Server transaction state primitives to request early deactivation For components that support EJB Server transactions the time between EJB Server s activate and deac
154. nection resource Obtain the initial JNDI context Context initContext new InitialContext Look up the resource factory using JNDI javax sgql DataSource ds javax sql DataSource initContext lookup java comp env jdbc EmployeeAppDB Get a database connection java sgql Connection connection ds getConnection For information about using the Adaptive Server plug in to add and configure resource references in EJB components see Chapter 6 Working with EJB Packages and Components 175 Configuring the EJB Server naming service UserTransaction references J2EE application components can use the Java Transaction API JTA UserTransaction interface to manage transactions A component instance can look up an object that implements the interface using the JNDI name java comp UserTransaction In this code sample an application component uses the interface to manage a transaction Get the initial JNDI context Context initContext new InitialContext Look up the UserTransaction object UserTransaction tran UserTransaction initContext lookup java comp UserTransaction Start a transaction tran begin data updates Commit the transaction tran commit Configuring the EJB Server naming service 176 Use the Naming Service tab on the Server Properties window to set the EJB Server s naming service options You can use the Naming Service properties to
155. nent State Using Java serialization To use Java serialization configure the following fields on the Persistence Tab in the Component Properties window Persistence Choose Java Serialization Storage Component Enter or choose the name of the component that manages interaction with the database See Storage components on page 116 for more information Connection Cache Enter the name of a JDBC connection cache that connects to the database The cache must have by name access enabled and be installed on all servers where your component is installed Table Enter the name of a database table where the serialized data is to be stored EJB Server creates the table if it does not exist Using automatic persistence To use automatic persistence configure the following properties fields on the Persistence Tab in the Component Properties window Persistence Choose Automatic Persistent State Storage Component Enter or choose the name of the component that manages interaction with the remote database See Storage components on page 116 for more information Connection Cache Enter the name of a JDBC connection cache that connects to the database The cache must have by name access enabled and be installed on all servers where your component is installed Table Enter the name of a database table where the serialized data is to be stored EJB Server creates the table if it does not exist 115 Stor age components St
156. next state depends on which of the transaction state primitives the method calls before returning The state transition also depends on whether the method returns with an uncaught exception See Using transaction state primitives on page 61 for more information Deactivation Deactivation indicates that the component is no longer bound to the client Methods can call either the completeWork or rollbackWork transaction state primitives to cause explicit deactivation of the instance As discussed in Using transaction state primitives on page 61 these primitives also affect the transaction s outcome Deactivation can also occur automatically under any of the following circumstances e Ifthe instance is participating in a transaction the instance is deactivated when the transaction commits rolls back or times out e Ifyou have configured the component s Instance Timeout property to a finite setting an instance is deactivated if the time between consecutive method calls exceeds the timeout value Resources tab component properties on page 80 describes how to configure this property Destruction Destruction occurs if the component instance cannot be recycled Supporting instance pooling in your component on page 54 describes how to ensure instance reuse If the component cannot be reused deactivation is followed by destruction of the instance 53 Component lifecycles Supporting instance pooling in your co
157. nnection cache properties on page 155 Configured connection cache entries appear on the right side of the window of the Adaptive Server plug in whenever you highlight the Installed Connection Cache folder on the left side of the window 153 Managing connection caches Modifying connection caches To view or modify a connection cache entry 1 Expand the Installed Connection Cache folder 2 Highlight the connection cache you want to modify 3 From the File menu select one of the following options e Properties view or modify this connection cache s properties See General tab connection cache properties on page 155 e Delete removes the connection cache from the server Modifying connection cache properties 154 To modify the properties of a connection cache 1 Double click the EJB Server for which you want to modify connection cache properties 2 Click on the Installed Connection Cache folder 3 Highlight the connection cache you want to modify 4 Select File Properties You see the Connection Cache Properties window which contains these tabs e General define general server properties e Advanced edit server property settings in their raw format that is as they are stored in the configuration repository You must use the cache properties file to manually configure the additional properties described in Other cache settings on page 156 After you have configured a connectio
158. nt process PowerJ 119 disabling EJB Server 24 disconnecting from the Adaptive Server plug in 23 distributed applications applet clients 129 connection caching 134 Java and EJB Server 129 Java client deploying 137 transaction management 132 Distributed Transaction Management DTM 159 dtm_tm_role system role 159 E early deactivation definition of 52 EJB 8 See also EJB clients EJB components client model 97 EJB Server support for 38 generating stubs for 98 home interfaces 89 JAR file 71 95 overview of 31 remote interfaces 91 EJB architecture 32 EJB clients 32 39 creating 97 EJB components creating 69 87 Index creating home interfaces for 89 defining remote interfaces for 91 deploying classes for 92 exporting 95 importing 71 introduction to 32 primary keys for 89 running 38 types of 33 using transactions in 35 EJB container 33 EJB Server 32 architecture 42 component lifecycle model 51 configuring 145 connection caching 128 134 creating applications for 41 description 5 developing distributed applications with Java 129 disabling 24 early deactivation 132 EJB component supportin 38 enabling 23 execution engine 6 instance pooling 136 Java components 128 131 overview 1 prerequisite knowledge 17 result set management 134 roles 94 serverruntime 6 ServerBean interface 136 services forcomponents 131 shutting down 26 starting 25 transaction management 132 transaction processing mo
159. ntity s data and then Program C reads the data Program C does not see the changes made by Program B To solve this problem when EJB Server detects a diamond it uploads data at method invocation and downloads data when the method completes 65 OTS XA transaction model Figure 5 3 Entity object diamond EJB Container Txi t Entity Object Txl OTS XA transaction model 66 EJB Server includes CORBA Object Transaction Service OTS and X Open architecture XA as one of its distributed transaction models The Transarc Encina transaction coordinator manages OTS XA transactions for EJB Server You can define components and component methods so that the transaction coordinator automatically handles transactions called implicit control You can also write code in the component or client to manage transactions called explicit control EJB Server provides for distributed transactions using the two phase commit protocol Two phase commit ensures that all changes to recoverable resources for example multiple database servers occur atomically and the failure of any resource to complete causes all other resources to undo changes Two phase commit consists of a prepare phase and an execution phase In the prepare phase the transaction coordinator validates that all resources are available In the execution phase the transaction coordinator executes all updates to the resources Note EJB Server does not currently su
160. nts can participate in an EJB Server transaction the EJB Server transaction manager ensures that all database changes performed by the participating transactions are all committed or rolled back All transactions are defined by the ACID test 55 The EJB Server transaction processing model Atomic Ifa transaction is interrupted all changes that the transaction has made are cancelled or rolled back e Consistent A transaction produces results that preserve invariant properties Isolated A transaction s intermediate states cannot be monitored or changed by other transactions transactions execute their results one after another e Durable The changes that a transaction completes are permanent How EJB Server transactions work In the Adaptive Server plug in you can declare EJB Server components to be transactional When a component is transactional and uses the EJB Server connection management feature commands sent on a third tier database connection are automatically performed as part of a transaction Component methods can call the EJB Server transaction state primitives to influence whether EJB Server commits or aborts the current transaction The component lifecycle is tightly integrated with the EJB Server transaction model Component instances that participate in a transaction are not deactivated until the transaction ends or until the component indicates that its contribution to the transaction is over that is it
161. o obtain resources such as database connections by name e The EJB Server component dispatcher which executes the component s implementation class and provides services such as transaction management database connection pooling and instance lifecycle management EJB component implementation The Java class that runs in the server implements the Bean s business logic The class must implement the remote interface methods and additional methods for lifecycle management EJB component types You can implement three types of EJB component each for a different purpose e Stateful session Beans e Stateless session Beans e Entity Beans Stateful session Beans A stateful session Bean manages complex processes or tasks that require the accumulation of data such as adding items to a Web catalog s shopping cart Stateful session Beans have the following characteristics e They manage tasks that require more than one method call to complete but are relatively short lived For example a session Bean might manage the process of making an airline reservation 33 About Enterprise JavaBean components e They typically store session state information in class instance data and do not survive server crashes e There is an affinity between each instance and one client from the time the client creates the instance until it is destroyed by the client or by the server in response to an expired instance timeout limit For exampl
162. object is the name context The referenced object in a name context can be a component within a package or even an existing name context the same way a named directory can contain a file or other named directory The collection of name context information each object and its bound name comprises the namespace When client applications reference an object they look to the namespace to cross reference or resolve the name with the referenced object Topic Page How does the EJB Server naming service work 167 JNDI support 171 Configuring the EJB Server naming service 176 Using an LDAP server with EJB Server 177 How does the EJB Server naming service work The process of binding objects is performed by a name server Each EJB Server can be its own name server or you can configure an EJB Server to use another server as its name server You can also use an external naming service such as an LDAP server in conjunction with the EJB Server naming service You set the naming service options for each EJB Server using the Naming Service tab on the Server Properties window 167 How does the EJB Server naming service work EJB Server initial context 168 The EJB Server naming service relies on an initial or default name context for each EJB Server You set the initial context when you set up the EJB Server Naming Service properties The server name context syntax follows a specific organization or schema You ca
163. om the third tier to the middle tier does not take place over the network EJB components or Beans are reusable modules of code that combine related tasks methods into a well defined interface EJB components contain the methods that execute business logic and access data sources You or the Administrator install the component s executable code on EJB Server Any number of independent Java or EJB applications clients can use the EJBs There are three types of Enterprise JavaBeans stateful session Beans stateless session Beans and entity Beans Each type of bean is a set of methods and is responsible for different tasks on behalf of the client All session Bean instances are transient They maintain a one to one relationship with the client They perform tasks and can store information in the database on the client s behalf Stateful session Beans manage complex tasks that require the accumulation of data Stateless session Beans manage tasks that do not store data between method calls Entity Bean instances are persistent They represent underlying objects typically a particular row in a database All three bean types work together to process a request and return information to the client Figure 1 1shows how the client interacts with the EJB Server and the database CHAPTER 1 About EJB Server Figure 1 1 EJB Server environment Client Client Host machine EJB Server
164. om wooster empl Employee lt remote gt lt ejb lLink gt Employee lt ejb link gt lt ejb ref gt For information about using the Adaptive Server plug in to add and configure EJB references in EJB components see Chapter 6 Working with EJB Packages and Components 174 Chapter 11 EJB Server Naming Services Resource factory references A resource factory is an object that you use to create resources You can assign a logical name to a resource factory in the deployment descriptor A resource ref element defines a single resource factory reference This code sample defines a reference to the resource factory that implements the DataSource interface lt resource ref gt lt description gt Data source for the database in which the Employee nterprise Bean records transactions lt description gt lt res ref name gt jdbc EmployeeAppDB lt res ref name gt lt res type gt javax sql DataSource lt res type gt lt res auth gt Container lt res auth gt lt resource ref gt A resource ref element contains e description This is optional e res ref name Resource reference name used in the application s code e res type Resource Java datatype that the application expects e res auth Resource sign on authorization Bean or Container This code sample obtains a reference to the resource factory that implements the DataSource interface and uses that reference to get a database con
165. omponent has a transaction attribute that determines how instances of the component participate in transactions In EJB Server you set the transaction attribute in the Transaction tab of the Component Properties dialog box When you design an EJB component you must decide how the Bean will manage transaction demarcation either programmatically in the business methods or whether the transaction demarcation will be managed by the container based on the value of the transaction attribute in the deployment descriptor A session Bean can use either Bean managed transaction demarcation or container managed transaction demarcation you cannot create a session Bean where some methods use container managed demarcation and others use Bean managed demarcation An entity Bean must use container managed transaction demarcation Table 3 1 lists the transaction attribute values Requires Supports Requires New or Mandatory are the values that specify container managed transaction demarcation You can set the Transaction Attribute for the component and for individual methods in the home and remote interfaces Values set at the method level override the component setting 35 About Enterprise JavaBean components 36 Table 3 1 Transaction attribute values Attribute Not Supported Description The component level default The EJB component s methods never execute as part of a transaction If the EJB component is activated by a client t
166. omponent icon b Choose File Generate Stubs Skeletons The stubs and skeletons dialog box displays c Select Generate Skeletons and click OK CHAPTER 6 Working with EJB Packages and Components Allowable primary key types Defining home interface methods d Specify a code base for the generated files e Click OK 16 The Adaptive Server plug in generates a template for the Bean implementation class suffixed with new for example MyBeanImpl java new Use this template as the basis for your Java implementation The Adaptive Server plug in also generates Java equivalents for the home and remote interfaces and for an entity Bean the primary key type 17 Compile the component source files and make sure they are correctly deployed to EJB Server See Deploying component classes on page 92 18 If you are testing the component with a Java applet generate and compile stubs using the SYBASE SYBASE_EJB htmil classes subdirectory as the Java code base Define an entity Bean s primary key as one of the following An IDL structure The structure should reflect the primary key for the database relation that the entity Bean represents In other words add a field for each column in the primary key Define the structure to match the intended Java package and class name For example if the Java class is to be foo bar PK1 define a new structure PK1 in module foo bar The name of a serializable Java class Enter the name of a ser
167. omponent support 7 Network protocol support 8 Administration and development tools 9 Client session and component lifecycle management 10 Naming services 12 Connection caching 13 Transaction management 13 Thread safety features 13 Result set support 14 Permissions and roles 15 PowerJ overview 15 About EJB Server Enterprise JavaBeans EJB Server is a component transaction server It supports the EJB server side component model for developing and deploying distributed enterprise level applications in a multi tiered environment It provides the framework for creating deploying and managing middle tier business logic In a three tier environment the client provides the user interface logic the business rules are separated to the middle tier and the database is the information repository The client does not access the database directly Instead the client makes a call to the EJB Server on the middle tier which then accesses the database About EJB Server The three tiers can reside on different machines or on the same machines EJB Server is designed to reside on the same machine as the database engines it serves Because the servers are on the same machine EJB Server can communicate with the database using Adaptive Server s high speed shared memory JDBC driver This approach ensures e High speed communication and data transfer even for large data sets e Secure data transmission because the transfer of information fr
168. on class and for entity Beans the primary key class The Adaptive Server plug in defines IDL interfaces for the interfaces and the primary key and defines an EJB component with default settings You can configure additional settings such as transaction attributes and database resource references using the Adaptive Server plug in Component Properties dialog box Define an EJB component from scratch in the Adaptive Server plug in using the IDL generation tools to define the home interface remote interface and primary key type The Adaptive Server plug in generates Java classes for the home and remote interfaces and primary key class as well as a template for the implementation class CHAPTER 3 Enterprise JavaBeans Overview EJB clients connecting to EJB Server EJB Server also supports the Enterprise JavaBean client model by generating EJB proxies and providing an EJB compliant implementation of the JNDI NamingContext class You can generate EJB style proxies for any IDL interface and use the proxies to call methods on components that implement that interface The NamingContext class can also be used in EJB components to instantiate home interfaces for intercomponent calls 39 EJB support 40 CHAPTER 4 About this chapter Contents Creating Component Based Applications This chapter describes the process of designing building and deploying applications with components executing in EJB Server Topic P
169. on in the Component Properties window this option is located on the Instances tab Stateless components cannot use instance specific data to accumulate data between method invocations Some situations require that you accumulate data across method invocations For example a PurchaseOrder component might have an addltem method that is called repeatedly to specify the contents of an order In lieu of instance specific data you can use one of these alternatives to accumulate data e Accumulate data in the database Use connection caching and database commands to accumulate data in the database This is the preferred technique e Accumulate data in the client Create a data structure that is passed to each method invocation and contains all accumulated data This technique is only practical if the amount of data is small Sending large amounts of data over the network will degrade performance e Accumulate data ina file If the accumulated data is small and represented by simple data structures you can store the data in a local file The EJB Server transaction processing model Transactions An EJB Server transaction is a transaction whose boundaries and outcome are determined by EJB Server Components can be marked as transactional in the Adaptive Server plug in If a component is transactional the EJB Server transaction manager ensures that the component s third tier database queries execute as part of a transaction Multiple compone
170. on the EJB Server you want to restart 2 Choose File Restart 25 Basic tasks 3 Press View Refresh Folder Note Restarting EJB Server may take a minute or two depending on the load on Adaptive Server You can stop and then restart EJB Server from the Adaptive Server plug in To start an EJB Server that has been shut down in another way you must use the sp_extengine system procedure To start EJB Server using the sp_extengine system procedure 1 Log in to Adaptive Server using isql 2 Enter this command sp_extengine SYB_EJB start where SYB_EJB is the logical name of the EJB Server Shutting down EJB Servers 26 You can stop EJB Server in three ways e From the Adaptive Server plug in e Using the sp_extengine system procedure e By shutting down Adaptive Server Enterprise To shut down EJB Server from the Adaptive Server plug in 1 Highlight the EJB Server you want to shut down 2 Press File Stop EJB To shut down EJB Server using sp_extengine 1 Log in to Adaptive Server using isql 2 Enter this command sp_extengine SYB_EJB stop where SYB_EJB is the logical name of the server To shut down both EJB Server and Adaptive Server 1 Log in to Adaptive Server using isql 2 Enter this command CHAPTER 2 Getting Started shutdown You can also use shutdown with the no wait option Note Issuing a kill 9 command on Adaptive Server will not shut down the
171. onal conventions for syntax statements in this manual are described in Table 1 Examples illustrating each convention can be found in the System Administration Guide Table 1 Syntax statement conventions Key Definition Curly braces indicate that you choose at least one of the enclosed options Do not include braces in your option Brackets mean choosing one or more of the enclosed options is optional Do not include brackets in your option Parentheses are to be typed as part of the command The vertical bar means you may select only one of the options shown The comma means you may choose as many of the options shown as you like separating your choices with commas to be typed as part of the command Each Sybase installation that has purchased a support contract has one or more designated people who are authorized to contact Sybase Technical Support If you cannot resolve a problem using the manuals or online help please have the designated person contact Sybase Technical Support or the Sybase subsidiary in your area XV xvi PART 1 Overview This part provides an overview of the Enterprise JavaBeans Server EJB Server and the information you need to start using EJB Server CHAPTER 1 About EJB Server This chapter presents an overview of the Enterprise JavaBeans Server EJB Server Topic Page About EJB Server 1 Features 5 The EJB Server execution engine 6 C
172. onent can explicitly begin commit and roll back new independent transactions by using the javax transaction UserTransaction interface Transactions begun by the component execute independently of the client s transaction If the component has not begun a transaction the component s database work is performed independently of any EJB Server transaction Default to component Method level default In the Transactions tab of the Method properties window choose this option if the method should inherit the transaction attribute set in the component properties CHAPTER 3 Enterprise JavaBeans Overview EJB container services The EJB container provides services to EJB components The services include transaction and persistence support Transaction support An EJB container must support transactions EJB specifications provide an approach to transaction management called declarative transaction management In declarative transaction management you specify the type of transaction support required by your EJB component When the Bean is deployed the container provides the necessary transaction support Persistence support An EJB container can provide support for persistence of EJB components An EJB component is persistent if it is capable of saving and retrieving its state A persistent EJB component saves its state to some type of persistent storage usually a file or a database With persistence an EJB component does not h
173. ons Xiv Classes interfaces methods and packages are shown in Helvetica within paragraph text For example SybEventHandler interface setBinaryStream method com Sybase jdbx package Objects and parameter names are shown in italics For example In the following example ctx is a DirContext object eventHdler is an instance of the SybEventHandler class that you implement The classes parameter is a string that lists specific classes you want to debug Java names are always case sensitive For example if a Java method name is shown as Misc stripLeadingBlanks you must type the method name exactly as displayed This book uses the same font and syntax conventions for Transact SQL as other Adaptive Server documents Command names command option names utility names utility flags and other keywords are in Helvetica in paragraph text For example select command isql utility f flag Variables or words that stand for values that you fill in are in italics For example user_name server_name Code fragments are shown in a monospace font Variables in code fragments that is words that stand for values that you fill in are italicized For example Connection con DriverManager getConnection jdbc sybase Tds host port props You can disregard case when typing Transact SQL keywords For example SELECT Select and select are the same About This Book If you need help Additi
174. ons using JDBC About JDBC The Java client application uses a transaction object to make a database connection A query object or DataWindow object makes the SQL query and manages the result set To present the data in the user interface you can use the DataWindow JavaBeans component or a data bound control The PowerJ Database wizard makes it easy to create database forms and generates much of the required code for instantiating the transaction and query objects and managing the data binding JDBC is a standard that describes how to connect to and talk to a database from within a Java application or applet JDBC is a set of Java interfaces not actual Java classes The JDBC interface also called the JDBC API provides Java programmers with a uniform interface to a wide range of relational databases To use JDBC you need a JDBC driver that implements the methods specified in the interface EJB Server provides the Sybase high speed shared memory driver for this purpose Building the application What you do Transaction object 138 PowerJ makes it easy to create a database form Typically you use the Form wizard to create the form The wizard gathers your specification and sets up the transaction object query object and bound controls that will display the retrieved data PowerJ takes care of most of the code for instantiating the objects making the database connection executing the query and populating the controls
175. ontrols just like the controls that display data They control the position of the cursor in the result set by calling methods of the query object such as moveFirst or movePrevious Building Enterprise JavaBeans 1 1 components PowerJ 3 6 supports Version 1 1 of the Enterprise JavaBeans specification See Sun EJB component specs See the EJB 1 1 specification from Sun Microsystems at http java sun com products ejb Using Power J you can automatically deploy EJB 1 1 components to EJB Server But EJB 1 1 components created in PowerJ can also be imported into other application servers by using that application server s importing methodology If you are currently using an application server that does not support EJB 1 1 component technology either upgrade your current application server to a version in which EJB 1 1 is supported or use EJB Server Creating an EJB 1 1 component is done in nearly the same way as described in the PowerJ 3 5 documentation You use the EJB 1 1 Component wizard to specify the EJB component and the wizard creates an EJB 1 1 target and optionally an associated JAR file The EJB 1 1 target contains the EJB component s implementation class the Home interface and the Remote interface 141 Building Enterprise JavaBeans 1 1 components 142 PART 3 Information for Administrators This part describes how to set up and manage the EJB Server CHAPTER 10 Configuring EJB Server This chapter d
176. ook for beginning users of the database management system This manual also contains descriptions of the pubs2 and pubs3 sample databases System Administration Guide provides in depth information about administering servers and databases This manual includes instructions and guidelines for managing physical resources security user and system databases and specifying character conversion international language and sort order settings Reference Manual contains detailed information about all Transact SQL commands functions procedures and datatypes This manual also contains a list of the Transact SQL reserved words and definitions of system tables Performance and Tuning Guide explains how to tune Adaptive Server for maximum performance This manual includes information about database design issues that affect performance query optimization how to tune Adaptive Server for very large databases disk and cache issues and the effects of locking and cursors on performance The Utility Guide documents the Adaptive Server utility programs such as isql and bcp which are executed at the operating system level The Quick Reference Guide provides a comprehensive listing of the names and syntax for commands functions system procedures extended system procedures datatypes and utilities in a pocket sized book Available only in print version The System Tables Diagram illustrates system tables and their entity r
177. opriate unless you have set an idle connection timeout of less than 30 seconds In that case you should specify a lower value for the garbage collection interval since connections are only closed while performing garbage collection In other words the effective idle connection timeout ranges from the idle connection timeout setting to the smallest integral multiple of the garbage collection interval com sybase ejb IdleConnectionTimeout Resolving Bean home names Specifies the time in seconds that a connection is allowed to sit idle When the timeout expires the ORB closes the connection The default is 0 which specifies that connections can never timeout The connection timeout does not affect the life of proxy instance references the ORB may close and reopen connections transparently between proxy method calls Specifying a finite timeout for your client applications can improve server performance If many instances of the client run simultaneously a finite client connection timeout limits the number of server connections that are devoted to idle clients Call the Context lookup method to resolve a Bean s home name to a proxy for the Bean s home interface If the server where the Bean is installed has a name context configured pass the server s name context as part of the Bean home name in the format Server name context Bean hom 103 Instantiating remote interface proxies Call javax rmi PortableRemo
178. or a form control or menu e In events and methods for nonvisual components on a form PowerJ calls these framework classes they are visible at design time as icons e Inclasses that you add to your application The PowerJ Reference Card and drag and drop programming make it easy to look up classes properties and methods and insert appropriate code in your program 121 About the development process Creating workspaces targets and classes What you do Targets Workspaces 122 First create a workspace A workspace contains targets and targets contain forms and other classes A target is an application applet class or collection that you create with PowerJ Types of targets include e Applet e Standalone Java application e A set of Java class files e Servlet e Enterprise JavaBeans component e JavaBeans component e WebApplication e ZIP JAR and CAB archive files You can run a target program anytime during a PowerJ session PowerJ builds the target by compiling Power files into Java class files and displaying the program s user interface Depending on the target type and your current run options your application may be displayed in the applet viewer in a Web browser or as a standalone program Not all targets can be run For example you cannot run a set of Java class files that make up a class library because it is not a complete application A WebApplication target can be used to tie other
179. or drop components e Update object properties e Generate stubs and skeletons for components Each of these tasks is described in subsequent chapters Starting the Adaptive Server plug in First start Sybase Central and then start the Adaptive Server plug in from within it Sybase Central You can start Sybase Central from the UNIX command line or from a Sybase Central shortcut on the desktop To start Sybase Central from the UNIX command line 1 Enter source SYBASE SYBASE csh 2 Then enter SSYBASE sybcent32 java scjview 22 CHAPTER 2_ Getting Started To start Sybase Central from Windows NT e Select the Sybase Central Java Edition shortcut from the desktop The installation process creates this shortcut for you The Adaptive Server Once the Sybase Central Java version is running you can start the Adaptive plug in Server plug in To connect to the Adaptive Server host 1 Select Tools Connect The Connect to Adaptive Server Enterprise screen displays Enter the sa user name and password Select the Adaptive Server host machine name or IP address Verify the Adaptive Server host port number nan A N Click Connect Disconnecting from the Adaptive Server host dSybase Central allows you to disconnect the Adaptive Server plug in from an Adaptive Server host so that you can connect to another server or reconnect to the same server without restarting the plug in To disconnect from the
180. or example interface calc File Name Purpose Calc java Defines an interface with methods equivalent to the component s methods Calc_Stub java Class that implements the interface CalcHolderjava Used when interface references are passed as an inout or output parameter The Adaptive Server plug in creates stubs for each interface and datatype defined in a module If your component references a module that contains multiple interfaces you will find that additional stub files are generated besides the stubs for the interfaces that are directly implemented by your component Compile the stub classes with a JDK 1 2 compiler Make sure that the CLASSPATH setting contains the code base directory and the EJB Server html classes subdirectory For example 99 Instantiating home interface proxies set CLASSPATH SYBASE SYBASE_EJB html classes SSYBASE SYBASE_EJB java classes SSYBASE SYBASE_EJB javac java Instantiating home interface proxies EJB clients use the Java Naming and Directory Interface JNDTI to resolve logical Bean home names to proxy instances for a Bean s home interface Each EJB container vendor provides an implementation of this interface that works with the vendor s server and network protocol Obtaining an initial naming context The core JNDI interface used by client applications is javax naming Context which represents the initial
181. or more Beans You can use a Java development tool such as Sybase PowerJ to define and develop Beans and create an EJB JAR file You can import JAR files in the EJB 1 1 format The Adaptive Server plug in reads the JAR file and creates a package containing a component for each Bean in the JAR file e From an EJB class file The Adaptive Server plug in can import component and method information from Java class files Use this method if you have created a Bean s interfaces and implementation class but have not created a deployment descriptor You will need to manually configure properties that would otherwise be read from the deployment descriptor You cannot import Java package files PowerJ deploys Enterprise JavaBeans directly to EJB Server If you are developing in PowerJ use the Enterprise JavaBean Deployment Wizard to install EJB components in EJB Server If using another IDE use the Adaptive Server plug in to import the Bean as described below Note Finder methods in an entity Bean s home interface can return java util Collection or java util Enumeration All EJB components defined in a package or an EJB JAR file must use the same type for finder method return values Importing an EJB 1 1 JAR file is a two step process 1 Deploy the JAR file to the repository 2 Install the package in the Installed Packages folder in the Adaptive Server plug in 71 Importing Enterprise JavaBeans 72 h lt Deploying a
182. orage components A storage component read and writes component state information from the database server If your component uses automatic persistence or Java serialization you must specify the storage component used to interact with the persistent data store The storage component uses the connection cache and database table identified on the Persistence tab in the Component Properties dialog box The storage component options are CtsComponenis JdbcStorage Uses a JDBC connection cache to provide persistent storage of component state This component has the Requires transaction attribute The component s state is saved in the context of any existing transaction associated with the component e CtsComponents JdbcStorageReqNew A copy of the CtsComponents JDBCStorage component that has the RequiresNew transaction attribute The component s state is saved using a separate transaction from that used to manage any database work performed by the component Supported Java IDL and JDBC SQL types 116 Table 8 3 lists the Java IDL and JDBC SQL types that EJB Server supports for persistent storage using mapped fields Types on one row are equivalent The JOBC SQL column lists the java sql Types constants that the storage component uses to bind to the database column When creating tables ensure that each column s type is compatible with the JOBC SQL type that corresponds to the mapped Java field Table 8 3 Supported Java IDL an
183. ou are not sure whether an entity Bean s data is already in the database Create methods throw a javax ejb CreateException exception if you attempt to insert a duplicate database row Example instantiating an Entity Bean This example instantiates an Entity bean that represents a customer credit account The primary key class has two fields custName is a string and creditType is also a string The example looks for a customer named Morry using the findByPrimaryKey method If FinderException is thrown the example calls a create method to create a new entity for customer Morry String _custName Morry String _creditType VISA custCreditKey custKey new custCreditKey custKey custName _custName custKey creditType _creditType custMaintenance cust 105 Calling remote interface methods try System out printin Looking for customer _custName cust custHome findByPrimaryKey custKey catch FinderException fe System out printin Not found Creating customer _custName try cust custHome create _custName 2000 catch CreateException ce System out println Error could not create customer _custName Calling remote interface methods After instantiating a proxy for the Bean call the remote interface methods to invoke the Bean s business logic You can call the proxy methods as you would invoke methods on any other object Managing transactions EJ
184. ox displays Choose a package from the drop down list of deployed packages in the repository Click OK Select View Refresh All The package appears in the Installed EJB Packages folder Optionally generate stubs and skeletons for the component Beans See Generating stubs and skeletons on page 86 CHAPTER 6 Working with EJB Packages and Components Importing EJBs from EJB class files Use the status dialog as a to do list In the deployment status dialog box the Adaptive Server plug in displays warnings for each setting that requires further attention before running the application You can copy and paste this text to a text editor to use as a to do list You may need to configure the following settings in the Component Properties dialog box before running EJBs e For Beans that use container managed persistence the settings described in Persistence for entity components e Resource references described in Configuring resource references e EJB references to components that are not installed with the JAR file described in Configuring EJB references e Environment properties described in Configuring environment properties You may need to configure the Role mapping settings in the Package Properties dialog box described in Role Mapping properties on page 94 The Adaptive Server plug in can import component and method information from Java class files Use this technique if you have created a Bean
185. participating in the transaction The application can roll back everything that took place in the transaction if any component could not complete its part of the work To define how a component participates in transactions 1 Choose a transaction coordinator for the EJB Server The transaction coordinator manages the flow of transactions that involve more than one connection and sometimes more than one data source 2 Set the component s transaction attribute to determine how the component participates in transactions 3 Code methods to call EJB Server s transaction state primitives to influence the transaction outcome Each task is described in detail below Choosing a transaction coordinator The transaction coordinator manages the flow of transactions that involve more than one connection and sometimes more than one data source To enable transactions involving multiple data sources you must configure your EJB Server to use a transaction coordinator that supports two phase commit such as OTS XA Setting the transaction attribute 132 Each EJB Server component has a transaction attribute that determines how instances of the component participate in transactions Values are Attribute Description Requires The component always executes in a transaction Use this option Transaction when your component s database activity needs to be coordinated with other components so that all components participate in the same transact
186. ponent including transaction management instance pooling and timeout settings 5 In PowerJ deploy the component to EJB Server This automatically creates CORBA skeletons for your component and optionally adds a proxy to the PowerJ component palette 6 In PowerJ create the client which can be a Java application or applet Add the proxy object and PowerJ InitialContext object to your client and you can access your component s methods as easily as if the component were available locally The InitialContext object takes care of connecting to your EJB Server component and initializing the proxy Information about building client applications and applets is in Building a Java client for a distributed or Web application on page 136 Building EJB Server components with PowerJ 130 A Java component for EJB Server can be an interface a class or a JavaBeans component You can implement any of these in PowerJ An EJB Server Java component follows the Enterprise JavaBeans implementation model Enterprise JavaBeans EJB components are portable to any server that follows Sun s EJB 1 1 specification An EJB session Bean models the interaction between an end user and the EJB Server For example in an online purchasing application a session Bean might keep track of a user s uncommitted purchases An EJB entity Bean represents a row of data stored in a database For example an entity Bean might represent a customer s purchase ord
187. pool default value is 10 You can increase this number if performance in Cache suffers due to an insufficient number of available connections Service The name of the Adaptive Service name is ignored for caches that use JDBC drivers other Name Server to which the Sybase than jConnect shared memory JDBC driver connects Other cache settings 156 The cache settings described in this section can not be set in the Adaptive Server plug in You must edit the underlying configuration file to change them Use a text editor to edit the cache s property file located in the SYBASE SYBASE_EJB Repository ConnCache subdirectory The file is CacheName props where CacheName represents the cache name as displayed in the Adaptive Server plug in Chapter 10 Configuring EJB Server JDBC connection properties For a JDBC connection cache these connection properties allow you to specify settings beyond those shown in the Connection Cache Properties dialog box Different JDBC drivers recognize different sets of properties For the Sybase high speed shared memory JDBC driver define cache properties in this form jdbc sybase shm null 0 Any property whose name does not begin with com sybase jaguar is passed to the JDBC driver as a connection property For example PACKETSIZE 2048 If a property setting conflicts with a setting in the Connection Cache Properties dialog box the dialog box setting takes precedence Enabling s
188. pport nested OTS XA transactions also called subtransactions If a method attempts to create a subtransaction the SubTransactionUnavailable exception is raised CHAPTER 5 Understanding Transactions and Component Lifecycles Component lifecycle and transactional behavior An OTS XA transaction coordinator uses XA resources to manage transactions An XA resource manages information using an XA compliant interface for example a database server or IBM s MQSeries a message queueing system The XA interface standard is an element of the X Open Distributed Transaction Processing DTP model Currently Sybase provides an XA compliant interface through CT Lib In addition EJB Server supports jConnect which is a JTA Java Transaction API compliant JDBC driver See the Managing XA resources on page 159 for detailed information about enabling and managing XA resources A component with the OTS Style transaction attribute enabled follows the standard component lifecycle as described in Component lifecycles on page 51 Generally OTS transactions behave in the same way as described in The EJB Server transaction processing model on page 55 For more information about component transaction attributes see Transactional component attribute on page 58 EJB Server does not support transactions that spawn over multiple EJB Servers 67 OTS XA transaction model 68 CHAPTER 6 Working with EJB Packages and
189. r 10 Configuring EJB Server describes basic configuration tasks to customize your installation such as creating new servers changing server properties and defining new connection caches e Chapter 11 EJB Server Naming Services describes how to use naming services to associate a logical name with an object The following documents comprise the Sybase Adaptive Server Enterprise documentation The release bulletin for your platform contains last minute information that was too late to be included in the books A more recent version of the release bulletin may be available on the World Wide Web To check for critical product or document information that was added after the release of the product CD use the Sybase Technical Library The Installation Guide for your platform describes installation upgrade and configuration procedures for all Adaptive Server and related Sybase products Configuring Adaptive Server Enterprise for your platform provides instructions for performing specific configuration tasks for Adaptive Server What s New in Adaptive Server Enterprise describes the new features in Adaptive Server version 12 5 the system changes added to support those features and the changes that may affect your existing applications About This Book Transact SQL User s Guide documents Transact SQL Sybase s enhanced version of the relational database language This manual serves as a textb
190. release area and reconfiguring XA resources See To enable EJB Server for OTS XA transactions on page 160 To create OTS XA transactions for XA resources See Table 10 5 for a description of the XA properties you enter when you create an OTS XA transaction resource 1 Double click the XA Resources folder 2 Double click the Add an XA resource icon in the right side of the window The Add an XA Resource wizard displays 3 Enter a name and description of the XA resource Press Next 4 Enter the server name a user name and a password in the Database Connection Information window Press Next 5 Enter a dll or class name in the Connectivity Information window Press Next 161 Managing XA resources 162 6 Enter a database name a default string an open string and a close string in the XA Driver Information window Note If the Open String is set incorrectly the EJB Server does not initialize Press Finish Table 10 5 XA resource properties Property Description Name A name for the XA resource Description A brief phrase describing the purpose of the XA resource Server Name Name of the XA resource server for shared memory Enter NetworkProtocol shm Server null Port 0 User Name A name you can use to access the server Password The password for the user DLL or Class Name The file name of the XA resource library Enter com sybase jdbc2 jdbc SybXADataSource Database Name
191. request and downloads the requested HTML page or applet Included with the applet are the Java stubs which through a proxy instantiate components and invoke the methods on those components 2 The client establishes a session with EJB Server The session unlike an HTTP connection allows the client and EJB Server to maintain a connection throughout the transaction 20 CHAPTER 2_ Getting Started Basic tasks 3 The client creates a component instance through a client side proxy The proxy used depends on the type of component being instantiated EJB Server validates the user against the component s access list If the user is validated the dispatcher checks the location and status of the component and creates an instance 4 The client invokes the component s business logic by executing its methods 5 The component may interact with the database server If it does the component obtains a connection to the database using the Sybase high speed JDBC driver 6 EJB Server returns the results from the database to the client 7 The client indicates that it has completed the operation EJB Server destroys the component instance or returns it to a pool for future client instantiations The client disconnects from EJB Server The installation and configuration process will preconfigure and start both your Adaptive Server Enterprise and its EJB Server As part of the post installation process you will start up Sybase Central the gr
192. rked Requires Transaction or Requires New Transaction since it calls methods in the Registrar and StudentBilling components and the work performed by the called components must be grouped in a single transaction Both Registrar and StudentBilling must be marked Supports Transaction or Requires Transaction so that their database updates can be grouped in the transaction begun by the Enrollment component Transaction Not Supported is useful when your component performs updates to a noncritical database For example consider a component whose sole function is to log usage statistics to the database Since usage statistics are not mission critical data you can choose Not Supported as the component s transaction attribute to ensure that the logging updates do not incur the overhead of using two phase commit 60 CHAPTER 5 Understanding Transactions and Component Lifecycles Determining when transactions begin Using transaction state primitives After a base client instantiates a transactional component the first method invocation begins an EJB Server transaction This instance is said to be the root instance of the transaction If the root instance invokes methods in other transactional components those components join the existing transaction The outcome of the transaction is determined by how the participating components call the transaction state primitives discussed in Using transaction state primitives on page 61
193. rror Naming exception ne getExplanation Instantiating remote interface proxies Use the home interface create and finder methods to create proxies for session Beans and entity Beans 104 CHAPTER 7 Creating Enterprise JavaBean Clients Instantiating proxies for a session Bean Instantiating proxies for an entity Bean A session Bean s home interface can have several create methods Each creates an instance with different initial value criteria The fragment below shows a typical call try Inventory inv invHome create catch CreateException ce System out printin Create Exception ce getMessage Each instance of an entity Bean represents a row in an underlying database table An entity Bean s home interface may contain both finder methods and create methods Finder methods Finder methods return instances that match an existing row in the underlying database A home interface may contain several finder methods each of which accepts parameters that constrain the search for matching database rows Every entity Bean home interface has a findByPrimaryKey method that accepts a structure that represents the primary key for a row to look up Finder methods throw javax ejb FinderException if no rows match the specified search criteria Create methods Create methods insert a row into the underlying database When instantiating an entity Bean proxy call a finder method first if y
194. rver binds any object implementations on the server to the server s initial name context If you use a EJB Server as a name server the name context can be a compound name with each organization level separated with a forward slash for example us sybase finance Use these options to specify whether the EJB Server is also a name server and whether to enable heartbeat detection Chapter 10 Configuring EJB Server If a server is not accepting connections the name server does not return a profile host port information to the client The name server also detects when a failed server is ready to accept connections again and starts routing client requests to that server e Click Enable as a Name Server to configure the EJB Server as a name server If you select this option you can then set the other Naming Service options described below Naming Server Strategy All Properties If you enabled the EJB Server as a name server indicate whether the server provides transient or persistent object name storage By itself an EJB Server name server provides transient storage However you can add persistent storage capabilities to EJB Server by using an external naming service such as an LDAP name server If you enable persistent storage enter the following information e The URL of the LDAP name server e A manager DN distinguished name for the LDAP server e The manager DN password The manager DN provides exclusive acce
195. ry storage When using the binary storage technique the table used by the JdbcStorage and JdbcStorageRegNew components has this schema 117 Table schema for binary storage 118 Column ps_key primary key Data format The table s primary key The column datatype is different for different component primary key types that is the IDL or Java type specified in the Primary Key field on the Persistence tab e Ifthe component has no primary key ps_key must be variable length binary 16 byte maximum length e Ifthe component s key is the IDL string type ps_key must be variable length character 255 character maximum length Ifthe component uses any other primary key type including java lang String ps_key must be variable length binary 255 byte maximum length This column cannot be null ps_size Integer cannot be null ps_bin1 Variable length binary 255 bytes maximum length can be null ps_bin2 Variable length binary 255 bytes maximum length can be null ps_bin3 Variable length binary 255 bytes maximum length can be null ps_bin4 Variable length binary 255 bytes maximum length can be null ps_data Binary large object This type must be functionally equivalent to a Sybase image type The JDBC driver used by the specified connection cache must allow access to the ps_data column using the JDBC setBytes and getBytes methods CHAPTER 9 Developing Applications with Power
196. s in the same transaction e Requires Transaction The component always executes in a transaction When the component is instantiated directly by a base client a new transaction begins If component A is activated by component B and B is executing within a transaction then A executes within the same transaction if B is not executing in a transaction then A executes in a new transaction e Requires New Transaction Whenever the component is instantiated a new transaction begins If component A is activated by component B and B is executing within a transaction then A begins a new transaction that is unaffected by the outcome of B s transaction if B is not executing in a transaction then A executes in a new transaction e Mandatory Methods may only be invoked by a client that has an outstanding transaction e Bean Managed Uses EJB 1 1 transactional behavior The component cannot inherit a client or other component s transaction The component can execute without a transaction or explicitly begin commit and roll back transactions by using the javax transaction UserTransaction interface for EJB components The following table lists design scenarios and the transaction attributes that apply to each 59 The EJB Server transaction processing model Table 5 1 Deciding on a transaction attribute Design scenario Your component interacts with the database and its methods may be called by another component as part of a larg
197. s work is done and ready for commit or that its work must be rolled back An instance s time in the active state corresponds to the beginning and end of its participation in a transaction Benefits of using EJB Server transactions A transaction involving multiple components 56 The benefits of using transactions to group database updates are clear You can easily code methods in a single component to implement transactions that run against a single data source However those methods may in turn be executed by another component which itself is defining a transaction In this situation error recovery becomes difficult For example consider the following scenario in which an Enrollment component calls both Registrar and Billing components In the following figure the Enrollment enroll method calls methods in the Registrar and StudentBilling components e Registar reserveSeat checks that a seat is available If so it decrements the count of available seats and adds the student to the course s enrollment list If no seats are available reserveSeat fails CHAPTER 5 Understanding Transactions and Component Lifecycles e StudentBilling addToBill checks that the student has a billable credit record If so addToBill adds the course cost to the student s bill for that semester If the student has a credit problem if for example she owes money for an overdue book addToBill fails Figure 5 2 An example EJB
198. sed applications 18 thread safety explanation of 13 threading models component properties to configure 78 threads management of 13 timeouts configuring properties for 80 for EJB clients 103 transaction 62 trace flag properties 148 transaction options OTS XA 58 transaction timeout component property 80 transaction EJB Server definition of 55 transactions and intercomponent calls 56 benefits of using 56 component properties to configure 77 configuring timeout property for 62 80 controlling outcome of 61 defining how components participate in 57 examples of 56 63 how to commit and roll back 61 management by EJB Server 132 multi component 61 overview of 55 semantics of 57 server processing of 55 specifying coordinators for 58 specifying how a component participates in 58 state primitives for 61 use in EJB components 35 transient storage 170 U URL for JDBC calls 155 user interface designing in PowerJ 125 user names 185 specifying in EJB clients 102 V verifying status of EJB Server 27 W Web applications about 119 X XA resources afconfig dat file 159 managing 159 186
199. serverA Pkg 1 CompY Server B Designated name server for Pkg1 Server A CompX CompY Server name myhost Server port 9050 An application referencing object CompY uses the URL of the name server followed by the object s name context For example iiop myhost 9050 us sybase serverA Pkg1I CompY The name server finds the name context in the namespace resolves the name context with the object it references then implements the object If you had not assigned an initial context to Server A the name server server B would create name contexts for objects Pkg1 CompX and Pkg1 CompY using the initial context of the name server In this case the client application can simply retrieve CompY using this URL iiop myhost 9050 Pkg 1 CompY Transient vs persistent storage 170 The EJB Server naming service inherently provides transient object name storage The name server is instantiated when you start an EJB Server and binds names to all the known object references The name server provides the bound name and object references to the EJB Server s session manager object Because this information is stored in memory the name context information is retained only as long as the EJB Server is running You can add persistent object name storage capabilities to EJB Server by using an external directory naming service such as an LDAP server The external server retains object name information
200. ss to all objects in the LDAP server database to bind and update the objects on the name server The manager DN and its password are part of the LDAP server configuration properties set by the server administrator Refer to your LDAP server documentation for complete information For advanced users only Select this tab to edit server property settings in the EJB Server configuration repository You can use this tab to edit any property prefixed with com sybase jaguar server Most server properties can be configured on other tabs in the Server Properties dialog box except the following e com sybase jaguar server authservice The name of a custom component that authenticates IIOP user connections The default is AseAuth DbAuth 149 Configuring an EJB Server 150 com sybase jaguar server authorization service The name of a custom component that authorizes user access to components and HTTP URLs com sybase jaguar server authorization permcachetimeout The length of time in seconds that the server can cache authorization data for a user s access to a resource The default is 7200 seconds which is equivalent to 2 hours com sybase jaguar server jvm debugging Whether in process Java debugging is enabled for servlets and Java components Set to true to enable debugging you must also start the debug version of the EJB Server com sybase jaguar server jvm nojit Specifies whether the Java Virtual Machine just in time JIT
201. structure When you add a new method Power inserts the method declaration and opens the code window so you can write the method s code When writing code you can use the PowerJ Reference Card to look up methods and properties of classes and components and then insert the method calls into your code In Java a class provides the definition of an object an object is an instantiation of a class An application with a user interface includes forms which are classes with specific support for the design environment You can also have classes that are not forms For these classes you work in the Workspace view and code editor You add methods to the class to contain the application logic You can add a class to a target and use the Workspace view to add properties methods and events to the class This is called a managed class because PowerJ has records of the functions it contains You can also add a Java source file to a target You can edit the source in the code editor but the Workspace view does not display the methods and properties of the class The extension for a source file is java 127 Building distributed and Web applications that use EJB Server PowerJ uses an enhanced file format for saving forms and managed classes Files for forms have the extension wxf files for managed classes have the extension wxc When you build your application PowerJ generates Java source files with the extension java that are then co
202. t for an EJB component must contain these classes e These packages com sybase ejb javax naming javax naming spi e Stubs for all components that your component calls If the called component s classes are loaded in a JAR file list the JAR file name in the custom class list e Other classes that your component loads and passes as parameters or return values for intercomponent calls or passes to clients as method return values and output parameter values e Classes that extend javax naming nitialContext or other javax naming classes and that are called by your component Troubleshooting ClassCastException errors When calling javax naming InitialContext lookup if you see NamingContext exceptions with root cause exception ClassCastException check for the following errors e You are casting to an incorrect type check the class name of the object returned by lookup e Your component has refresh enabled and the custom class list does not contain some required classes e Your component has refresh enabled and calls a component that has refresh disabled or vice versa Modifying packages To modify an existing package 1 Highlight the package you want to modify 93 Configuring package properties 2 From the File menu select one of the following options e Properties Displays the Package Properties window described in Configuring package properties on page 94 Make any modifications required
203. t participates in EJB Server transactions you can call transaction state primitives to explicitly commit or roll back database updates performed in a method Components that use the Bean Managed or OTS Style transaction attribute must explicitly begin and end transactions using the APIs described below For components that use any other attribute EJB Server implicitly commits each method s work when the method returns unless the method has requested rollback Different component types use different transaction APIs 133 Building distributed and Web applications that use EJB Server EJB components using attribute Bean Managed Only EJB session Beans can use the Bean Managed transaction attribute Components using this attribute must call the methods in the interface javax transaction UserTransaction to begin commit and roll back transactions If the component is not a stateful session Bean then transactions begun in a method call must be committed or rolled back before the method returns Otherwise EJB Server logs a runtime error and returns an exception to the client EJB components using any other attribute When an EJB component does not use the Bean Managed transaction attribute EJB Server implicitly commits the component s work after each method returns To override the default outcome call the EJBContext setRollBackOnly method Database access and result set management How it works Sending a ResultSet object to
204. t to the EJB Server log file To establish the level of detail for logging and tracing select the Log Trace tab Table 10 2 describes the logging and trace properties 147 Configuring an EJB Server Naming Service Initial Context Naming Server 148 Table 10 2 Debug Trace properties Property Log File Name Description The name of the EJB Server log file This file defaults to srv log in the Adaptive Server startup directory srv log logs a wide range of information and is helpful in isolating problems You can create the log file in an alternate directory by prefixing a full path to the file name you enter Log File Size Bytes The size in bytes to which the log file grows before it is truncated Truncate Log on Startup When this flag is set the log truncates every time the server is restarted Keep in mind that if the server crashes and this flag is set you will lose the log file and the information it contains Trace Attentions If set traces attentions received or acknowledged by EJB Server Trace Network Driver If set traces Net Lib driver requests APIs Trace Network Driver If set traces network layer protocol requests Requests Select the Naming Service tab on the Server Properties window to set the EJB Server s naming service options You can use this property sheet to configure an EJB Server to be a name server Enter the EJB Server default name context The name se
205. tStackTrace return 108 CHAPTER 8 Managing Persistent Component State You can code components to store state information in the database rather than in memory Doing so offers failover for stateful components and allows you to map relational data to a component interface using the EJB entity Bean model Topic Page Persistence for entity Java Beans 109 Persistence for stateful components 114 Storage components 116 Supported Java IDL and JOBC SQL types 116 Table schema for binary storage 117 Persistence for entity Java Beans Entity components present an object view of relational data to clients each instance of an entity component maps to a row in a database relation Entity components must be EJB entity Beans implemented according to the EJB 1 1 standard see Chapter 6 Working with EJB Packages and Components You can implement entity components by following these requirements e Define a primary key type for the component See Allowable primary key types on page 89 for more information e Create a home interface for the component with a findByPrimaryKey method and optionally additional finder and create methods See Patters for finder methods for more information For an entity component you can manage persistence using these techniques 109 Persistence for entity Java Beans e Component managed In this technique you implement the code that reads and writes persistent dat
206. tart the EJB Server the JNDI classes required for the server s JDK version are configured automatically JNDI J2EE features EJB Server supports the JNDI features required by the Java 2 Enterprise Edition J2EE platform specification In J2EE you can use the application component s naming environment to customize an application s business logic without accessing the source code The application component s container implements the environment as a JNDI naming context and provides the JNDI interfaces to access the environment properties that you define in the deployment descriptor 171 JNDI support Environment properties 172 When you deploy a J2EE application use the deployment descriptor to define all the environment properties that the application component needs to access This sample code defines the environment property env entry maxExemptions as an Integer and sets its value to 10 lt env entry gt lt description gt The maximum number of tax exemptions lt description gt lt env ent ry name gt maxExempt ions lt env entry name gt lt env entry type gt java lang Integer lt env entry type gt lt env entry value gt 10 lt env entry value gt lt env entry gt The information between the opening and closing env entry tags defines an environment entry element which consists of e description This is optional env entry name The environment property name relative to the j
207. teObject narrow to narrow the returned object to the Bean s home interface class narrow requires as parameters the object to be narrowed and a java lang Class reference that specifies the interface type to returned To obtain the java lang Class reference use Home class where Home is the Bean s home interface type Cast the object returned by the narrow method to the Bean s Java home interface The lookup method throws javax naming NamingException if the Bean home name cannot be resolved or the home interface proxy cannot be created This can happen for any of the following reasons e The server address specified with the Context PROVIDER_URL property is incorrect or the server is not running e Authentication with the specified credentials failed e The Bean is incorrectly configured on the server For example a skeleton has not been generated or the Bean s properties specify the wrong implementation class Check the server s log file if the cause of the error is not clear from the exception s detail message The call below instantiates a proxy for a Bean with Java home interface test p1 Stateless1 Home and Bean home name of test p1 Stateless1 import test pl import javax naming javax rmi PortableRemoteObject try Object o ctx lookup test pl Stateless1 StatelesslHome home StatelessilHome PortableRemoteObject narrow o StatelesslHome class catch NamingException ne System out printin E
208. terface repository Component interfaces are stored in standard CORBA Interface Definition Language IDL Interfaces can be defined by importing compiled Java classes or standard format EJB JAR files Server side component support EJB Server supports Java components that follow the JavaSoft Enterprise JavaBeans EJB specification version 1 1 An Enterprise JavaBean is a nonvisual transactional component that is implemented in Java Chapter 6 Working with EJB Packages and Components describes how to create EJB components Features Client stub proxy support Applications invoke an EJB Server component using a stub or proxy object The stub or proxy acts as a local surrogate for the remote component it provides the same method signatures as the component and hides the details of server communication Stubs and proxies are available for Java EJB Any component can be invoked via a Java stub class The Adaptive Server plug in generates source code for Java stubs At runtime your client program instantiates the stub When you call methods on the stub class the stub transparently invokes the component method on the EJB Server Using HTML pages Java applets and EJB Server s built in HTTP support you can create zero install applications that have no client machine installation requirements other than the presence of a Java capable Web browser EJB Server supports the EJB Java client model e EJB Your program us
209. the EJB Server naming service work sss 167 EJB Server initial context 0 eee eee eeeeeeeeneeeeeeeeeeeeeeeeeees 168 Name binding example eceeceeeseeeeeeeeeeeeeeeeeeeeeeeneeteaes 169 Transient vs persistent Storage s e 170 INDISSUPPOlt aAA E E TTT 171 UNDI JZEE faturo Sirianni naiaiae itatta aitatua tantan 171 Configuring the EJB Server naming service seseeeeeceeeeeeee 176 Name binding password security eeeeeeeeeeeeeerrierrrereene 177 Using an LDAP server with EJB Server seese 177 vi Contents LDAP object schema and EJB Server objects ee 178 Storing EJB Server object bindings on an LDAP server 178 vii Contents viii About This Book Audience How to use this book This book describes how to create Enterprise JavaBean EJB clients and components for Sybase EJB Server and Adaptive Server Enterprise This book is intended for EJB component developers Sybase System Administrators and others interested in EJB components This book will assist you in creating EJB components and clients for Sybase EJB Server It contains these parts and chapters Part 1 Overview provides a general description of the EJB Server and sufficient information to allow you to get started using it Part 1 contains these chapters Chapter 1 About EJB Server provides an overview of EJB Server a summary of EJB Server features and a description of Sybase Power Chapter 2
210. the state of the transaction if any in which the method is executing e isInTransaction Query whether the current method is executing in the context of a transaction 61 The EJB Server transaction processing model Transaction Timeout property 62 e isRollbackOnly Query whether the current transaction is doomed to be rolled back or is still viable The following table describes how the transaction primitives are invoked in Java components Table 5 2 Java transaction primitives Transaction Java InstanceContext primitive method completeWork completeWork rollbackWork rollbackWork continueWork continueWork disallowCommit None You can achieve the same effect by calling and then raising an exception if deactivate is called before the next method invocation isInTransaction inTransaction isRollbackOnly isRollbackOnly Any participating component can roll back the transaction by calling the rollbackWork primitive Java components can also cause a rollback by returning an unhandled exception Only the action of the root component determines when EJB Server commits the transaction The transaction is committed when the root component returns with a state of completeWork and no participating component has set a state of disallowCommit You can use the transaction state primitives in any component the component does not have to be declared transactional Calling completeWork or rollbackWork from me
211. them in Java applications Business logic components consist of methods that implement business rules and other application logic These components can be included in a client application but are more typically hosted in a component server like EJB Server in a distributed application User interface components are used in client applications to enhance the user interface Typically user interface components extend standard user interface classes For example a custom list box component might provide custom sorting methods or a text box or check box might have data awareness In PowerJ you can add components to the component palette and include them in your applications You can put components on your forms customize them and use their methods through the Reference Card and drag and drop programming For business logic components on an EJB Server when you add a component to PowerJ a proxy for it is added to the palette You can then use distributed components just as you would local components CHAPTER 9 Developing Applications with PowerJ and EJB Server How you build it In PowerJ it is easy to create JavaBeans components A Bean might be an encapsulated user interface component such as an enhanced button with custom functionality or it might be a business logic component that includes methods and events You can use the class method property and event wizards to create the Java classes for the component You can also write co
212. thods causes early deactivation The root instance s Transaction Timeout property specifies the maximum duration of an EJB Server transaction The default timeout period is infinite You can configure finite timeouts in the Adaptive Server plug in as described in Resources tab component properties on page 80 A transaction begins when a base client activates a transactional component this component is the root component of the transaction The root component s Transaction Timeout property determines the maximum duration of the transaction If the transaction is not committed or rolled back within the allotted time it is automatically rolled back In this case the client receives the CORBA TRANSACTION_ROLLEDBACK exception when it tries another method invocation The client s object reference remains valid and the transaction can be retried CHAPTER 5 Understanding Transactions and Component Lifecycles Example Transactions are never rolled back in the middle of a method invocation If the timeout occurs during a method invocation and the method does not commit the transaction the transaction is rolled back when the invocation completes As discussed in Benefits of using EJB Server transactions on page 56 EJB Server transactions are most useful when your application uses intercomponent calls As an example consider the scenario illustrated in A transaction involving multiple components on page 56 The pse
213. tion class is serialized and deserialized to save and restore component state e Component Class Your component implementation manages persistence Used for EJB entity Beans Automatic Persistent State EJB Server manages the persistent state of your component Primary Key The primary key for EJB entity Beans Specify the IDL type of the components primary key For example foo bar MyPK Components with a primary key must have a findByPrimaryKey method in their home interface and can have additional finder methods that allow clients to look up instances that match a desired primary key Unless you have defined an entity Bean by importing class or EJB JAR files you must define the primary key type yourself For an EJB entity Bean choose from the types listed in Allowable primary key types on page 89 Storage Component Specifies the name of a component that reads and writes component state information from a remote database server Required when using automatic persistence or when using component managed persistence with an implementation that delegates to EJB Server s built in storage component Connection Cache Specifies the connection cache used by the storage component The cache must be installed on all servers where your component runs and allow by name access Table Specifies the name of the database table to store component state information Create the table in the default database rather t
214. tivate calls coincides with the beginning and end of that instance s participation in an EJB Server transaction Using components that support instance pooling increases the scalability of your application Instance pooling eliminates execution time and memory consumption that would otherwise be spent allocating unnecessary component instances 11 Features Coded character set conversions Naming services Configuring naming services 12 EJB Server supports multiple coded character sets for clients and components When a client and component use different coded character sets the EJB Server automatically converts character data from one character set to another For example if the client uses the roman8 character set and the component uses iso_1 EJB Server converts string parameters and return values automatically from roman8 to iso_1 when the client calls the component methods In accordance with the Java standards Java components use 16 bit Unicode Unicode contains mappings for all characters in all other known coded character sets Note EJB Server and its host Adaptive Server must use the same character set If you change the character set on Adaptive Server you must perform a similar change on EJB Server See Configuring an EJB Server on page 145 When multiple servers are involved in your application the naming service allows you to specify logical server names rather than server addresses For example
215. to delete 2 Select File Delete Table 10 6 Listener profile properties Property Description Commenis example Protocol Select the protocol from the TDS IIOP and HTTP do not provide encryption TDS and drop down list IIOP provide user name and password based authentication IIOP e HTTP e TDS Host name The name or IP address of the Use the actual machine name or IP address This allows EJB Server host to which the clients from other machines access to EJB Server listener is being assigned Port The port number on the host to Make sure that the port is not in use by any other service 164 which the listener is assigned Chapter 10 Configuring EJB Server Replacing an EJB Server Use the Sybase Installer to add an EJB Server to a new Adaptive Server host You can replace an existing EJB Server with a new EJB Server using the Adaptive Server plug in Warning Replacing an EJB Server removes the existing EJB Server from Sybase Central and from the sysservers table in the master database Connection caches and packages associated with the old EJB Server are lost Use caution when replacing an EJB Server Before replacing an EJB Server make a list of the packages and connection caches in the existing server that you want to redeploy to the new server To replace the EJB Server 1 Highlight the Enterprise JavaBeans folder 2 Double click the Add an EJB Server icon in the right window The Add an EJB Server
216. torage 170 pooling component property 79 port numbers configuring for servers 8 specifying in EJB clients 102 Power 9 about 15 application logic 127 building EJB components 141 classes 123 127 code window 124 component palettes 125 component targets 131 components 120 183 Index database access 126 database forms 138 data bound controls 127 140 defining EJB components in 38 deploying components 48 development process 119 events 127 forms 125 managed classes 127 menus 126 methods 127 projects 122 query object 126 139 targets 122 transaction object 126 138 user interface 125 preconfigured listeners security profiles 163 primary keys specifying for EJB components 89 properties listeners 164 of components 75 of EJB Server packages 94 to configure component instance allocation 78 to configure threading behavior 78 to control transactional behavior 77 protocols HTTP 8 HOP 8 supported 8 proxies purpose of 8 proxy objects and stubs 18 definition of 8 R refresh disabling for components 85 replacing an EJB Server 165 restarting server after modifying components 146 155 methods 146 155 184 packages 146 155 result sets explanation of 14 roles EJB Server 15 94 mapping of 94 runtime server engine 6 runtime environment 20 S server naming service 167 server applications see components EJB Server server debugging and trace properties log file name 148 log file size 148 truncate log
217. udocode below shows the logic used to ensure that the work performed by the Registrar reserveSeat and StudentBilling addToBill occurs within the same transaction In the Registrar component the reserveSeat method must check the number of seats If there is space for the new student then the method adds the student decrements the count of available seats and sets a state of completeWork If a seat is not an available the method calls rollbackWork to roll back the current transaction Here is the pseudocode for Registrar reserveSeat check number of seats if enough seats decrement number of seats add student to enrollment list completeWork else rollbackWork end if The transaction attribute for Registrar must be Requires Transaction so that the query for available seats and the update of available seats always occur in the same transaction In the StudentBilling component the addToBill method must verify the student s credit If the student does not already owe money the method adds the cost to the semester bill and sets a state of completeWork If the student owes money the method calls rollbackWork to roll back the current transaction Here is the pseudocode for StudentBilling addToBill check student s balance if balance gt 0 add cost to bill debit balance 63 The EJB Server transaction processing model completeWork else rollbackWork end if The transaction attribute for StudentBilling must
218. ul session Beans this property must be enabled for the standard EJB passivation and activation to occur It must be disabled if you want to configure a stateful session Bean to support failover using the Persistence tab properties see Persistence tab component properties on page 82 Reentrant When this option is enabled an instance is allowed to participate in loopback call sequences which are call sequences where one of the Bean s methods calls another component which in turn calls a method in the calling Bean instance Most Beans are not implemented to support reentrancy and you must not enable this option unless the Bean developer has verified that the implementation allows it Resources tab component properties Properties on this tab govern the allocation and deallocation of resources required by the component Transaction Timeout A component s Transaction Timeout property specifies the maximum duration of an EJB Server transaction See Chapter 5 Understanding Transactions and Component Lifecycles for more information on EJB Server transactions 80 CHAPTER 6 Working with EJB Packages and Components The timeout period is configured in seconds with O indicating infinity that is no timeout If the component s Transaction Timeout property is not set the default is inherited from the server properties The default for a new server is 0 When specifying timeouts a resolution of 5 seconds is re
219. ver properties are listed in alphabetical order 3 Enter a stack size in the Value field specified in bytes as a decimal number The field will display with no value if you have not specified a value before This means the default setting is in effect 4 Stop and restart the EJB Server 151 Character sets Character sets EJB Server and Adaptive Server must have identical character sets If you change the value of the Adaptive Server character set you must also change the value of the EJB Server character set You can set the EJB Server character set in the All Properties tab of the EJB Server properties sheet See All Properties on page 149 Shared memory connections 152 Adaptive Server uses the value of the number of user connections configuration parameter to establish the number of shared memory connections for EJB Server Thus if number of user connections is 30 Adaptive Server establishes 10 shared memory connections for EJB Server Shared memory connections are not a subset of user connections and are not subtracted from the number of user connections To increase the number of user connections for shared memory you must 1 Increase number of user connections to a number one third of which is the number of desired shared memory connections 2 Reboot Adaptive Server Although number of user connections is a dynamic configuration parameter you must restart the server to change the number of user connect
220. within the file 13 Features Result set support 14 Whenever possible avoid the use of static class variables Also avoid sharing stateful being able to maintain information about the state of a resource resources such as database connections or file descriptors In cases where data and resources are shared there are two ways to ensure thread safety in a component Configure the component for single threaded execution Each component defined in EJB Server has a Concurrency property By default components are multithreaded and instances are allowed to execute concurrently on different threads You can also request single threading in a single threaded component each method invocation blocks other method invocations on instances of the same component For components in general single threading is the least desirable alternative because it increases the likelihood that clients will block each other s execution and increase the apparent response time of client applications Single threading makes sense for some specific problems for example to share an output file among component instances you can create a single threaded component with methods that write to the file another alternative is to use explicit threading primitives when implementing code that writes to the file such as the Java synchronized keyword Store shared data on the database You can use connection caching and store the data on the database lett
221. you do not set this property the default is iiop localhost 9000 java naming security principal Specifies the user name for the EJB Server session Required if user name password authentication is enabled for your EJB Server java naming security credentials Specifies the password for the EJB Server session Required if user name password authentication is enabled for your EJB Server com sybase ejb RetryCount Specify the number of times to retry when the initial attempt to connect to the server fails The default is 5 com sybase ejb RetryDelay 102 Specify the delay in milliseconds between retry attempts when the initial attempt to connect to the server fails The default is 2000 CHAPTER 7 Creating Enterprise JavaBean Clients Property name com sybase ejb socketReuseLimit Description Specify the number of times that a network connection may be reused to call methods from one server The default is 0 which indicates no limit The default is ideal for short lived clients In Sybase testing settings between 10 and 30 proved to be a good starting point If the reuse limit is too low client performance degrades com sybase ejb GCInterval Specifies how often the ORB forces deallocation Java garbage collection of unused class references Though this property is set on an individual ORB instance it affects all ORB instances The default is 30 seconds The default is appr
222. your application since it eliminates repetitive login logoff operations for connections to databases Connection caching is also required for EJB Server transactions to function as intended You must define a connection cache for the database that your components interact with and then implement your components to use cached connections See Managing connection caches on page 153 which describes how to define connection caches in the Adaptive Server plug in components and clients With the design in place your component developers and client developers can begin implementing the clients and components that form the application CHAPTER 4 Creating Component Based Applications Implementing components Design and implement the client To create an EJB component use PowerJ or another JDK 1 2 compatible development tool to create the component From PowerJ you can import the component definitions into EJB Server and deploy the component on the EJB Server If using another development tool you must perform these tasks with the Adaptive Server plug in To learn how to build EJB components see Chapter 6 Working with EJB Packages and Components Client developers can work concurrently with component developers To allow prototyping and testing of client programs you may want to create a client test server that hosts stubbed versions of the application components that is components with minimal method implementations
223. ywhere Adaptive Server IQ Adaptive Warehouse AnswerBase Anywhere Studio Application Manager AppModeler APT Workbench APT Build APT Edit APT Execute APT FORMS APT Translator APT Library Backup Server ClearConnect Client Library Client Services Data Pipeline Data Workbench DataArchitect Database Analyzer DataExpress DataServer DataWindow DB Library dbQueue Developers Workbench Direct Connect Anywhere DirectConnect Distribution Director E Anywhere E Whatever Embedded SQL EMS Enterprise Application Studio Enterprise Client Server Enterprise Connect Enterprise Data Studio Enterprise Manager Enterprise SQL Server Manager Enterprise Work Architecture Enterprise Work Designer Enterprise Work Modeler EWA Financial Fusion Financial Fusion Server Gateway Manager ImpactNow InfoMaker Information Anywhere Information Everywhere InformationConnect InternetBuilder iScript Jaguar CTS jConnect for JDBC KnowledgeBase MainframeConnect Maintenance Express MAP MDI Access Server MDI Database Gateway media splash MetaWorks MySupport Net Gateway Net Library ObjectConnect ObjectCycle OmniConnect OmniSQL Access Module OmniSQL Toolkit Open Client Open ClientConnect Open Client Server Open Client Server Interfaces Open Gateway Open Server Open ServerConnect Open Solutions Optima PB Gen PC APT Execute PC DB Net PC Net Library Power power stop PowerAMC PowerBuilder PowerBuilder Foundation Class Library
224. ze using the com sybase jaguar server stacksize parameter Chapter 10 Configuring EJB Server Configuring server stack size Your EJB Server has a stack size property that determines the amount of memory reserved for the call stack associated with each thread created by the server EJB Server runs each client request on a different thread so the stack size is the dominant factor in determining how many client requests can be served simultaneously The default stack size is 256 K This is appropriate for almost all situations and provides adequate reserve memory for the worst case loads that have been tested by Sybase engineering and customers For production servers that see heavy use from large numbers of clients you may wish to decrease the stack size from the default value However you must ensure that the stack size is adequate for the components running on the server If the stack size is too small your server may experience thread stack overflow errors these are recorded in the server log Warning Under no circumstances should you reduce the stack size below 64K If you reduce the stack size test your server thoroughly under worst case client loads and check the log for stack overflow errors Configuring stack size for servers 1 Highlight the icon for the EJB Server and select File Server Properties 2 Display the All Properties tab Scroll down if necessary to the com sybase jaguar server stacksize property Ser

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