Creating EclipseLink Files for Deployment (ELUG)

For the latest EclipseLink documentation, please see http://www.eclipse.org/eclipselink/documentation/

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This section includes EclipseLink information that you need when creating deployment files for various types of applications.

For more information on packaging and deployment, see the following:

• Introduction to the EclipseLink Deployment File Creation
• Integrating EclipseLink with an Application Server
• Packaging a EclipseLink Application
• Deploying a EclipseLink Application
• Packaging and Deploying EclipseLink JPA Applications
• Creating Deployment Files for EclipseLink Web Services

Introduction to the EclipseLink Deployment File Creation

Depending on the type of application you are deploying, you may need to create any of the following deployment files:

• project.xml File
• sessions.xml File

Workbench provides the ability to create deployment files from a Workbench project. After you build a project, you have two options to create the deployment files:

• Create XML deployment files that require no compiling.
• Create Java source files, which you compile and deploy outside of Workbench.

We recommend XML deployment because XML files are easier to deploy and troubleshoot than compiled Java files. This approach gives you a very flexible configuration that enables you to make changes safely and easily. XML deployment files do not require third-party applications or compilers to deploy successfully.

Note: If you are using JPA, you can use annotations to specify most of what you formerly specified in deployment descriptors. Use deployment descriptors to override annotations or specify options not supported by annotations.

project.xml File

The project.xml file is the core of your application. It contains the descriptors and mappings you define and also includes any named queries or finders associated with your project.

XSD File Format

The project.xml file XSD is persistence_1_0.xsd and it is located in the <ECLIPSELINK_HOME>\xsds directory.

See EclipseLink/XSDs for more information.

POJO Applications and Project Metadata

For a POJO application, you define your project metadata in a project.xml file.

The project.xml file provides a simple and flexible way to configure, modify, and troubleshoot the project metadata. Because of these attributes, the project.xml file is the preferred way to configure an EclipseLink project.Workbench provides a graphical tool to build and edit the project.xml file. For information on creating projects with Workbench, see Creating the project.xml File with Workbench.

JPA Applications and Project Metadata

For a JPA application, you can express project metadata using JPA annotations, persistence.xml, orm.xml, and EclipseLink JPA annotation and persistence.xml property extensions. The EclipseLink JPA persistence provider interprets all these sources of metadata to create an in-memory EclipseLink session and project at run time.

Using EclipseLink JPA, you also have the option of specifying your metadata using EclipseLink sessions.xml and project.xml while accessing your persistent classes using JPA and an EntityManager. For more information, see What You May Need to Know About EclipseLink JPA Overriding Mechanisms.

Creating the project.xml File with Workbench

Because you must synchronize the project.xml file with the classes and data source associated with your application, we recommend that you not modify this file manually. Workbench ensures proper synchronization, and is the best way to make changes to the project. Simply modify the project in Workbench and redeploy the project.xml file. Using this option reduces development time by eliminating the need to regenerate and recompile Java code each time the project changes.

See Exporting Project Information for detailed information on exporting the deployment XML information.

Note: You can name this file with a name other than project.xml; however, for clarity, this discussion assumes that the file has not been renamed.

Creating project.xml Programatically

Optionally, you can use the DeploymentXMLGenerator API to programatically generate the project.xml file in either of the following ways:

• From an application, instantiate the DeploymentXMLGenerator and your java source. Call the following method:generate (<MW_Project.mwp>, <output file.xml>)
• From the command line, use the following:

java -classpath eclipselink.jar;eclispelinkmw.jar;
org.eclipse.persistence.tools.workbench.mappings.DeploymentXMLGenerator <MW_Project.mwp> <output file.xml>

Before you use either method, ensure that your classpath includes the <ECLIPSELINK_HOME>\jlib\eclipselink.jar and <ECLIPSELINK_HOME>\utils\workbench\jlib\eclipselinkmw.jar files.

Note: If you are using EJB 3.0, you can use annotations to specify most of what you formerly specified in the project.xml file. To override annotations or specify options not supported by annotations, you can still provide a project.xml file in your EJB 3.0 application.

sessions.xml File

Each EclipseLink project belongs to an EclipseLink session. A session is the facade through which an application accesses EclipseLink functionality (for more information on sessions, see EclipseLink Sessions).

XSD File Format

The sessions.xml file XSD is eclipse_persistence_sessions_1_0.xsd and it is located in the <ECLIPSELINK_HOME>\xsds directory as well as on the web at http://www.eclipse.org/eclipselink/xsds/eclipse_persistence_sessions_1_0.xsd.

When you use the XSD formatted sessions.xml file, the EclipseLink run time separates sessions.xml file validation from session instantiation. Separating XML file formatting problems from Session Manager session instantiation problems simplifies troubleshooting. Exceptions thrown during validation clearly indicate that the failure is due to an invalid sessions.xml file, as the following illustrates.

Enhanced Validation Exceptions

Exception [ECLIPSELINK-9010] (EclipseLink): org.eclipselink.exceptions.SessionLoaderException
Exception Description: A End tag does not match start tag 'session'. was thrown while parsing the XML file against the XML schema.
Internal Exception: oracle.xml.parser.v2.XMLParseException: End tag does not match start tag 'session'.

POJO Applications and Session Metadata

For a POJO application, you define your sessions in a sessions.xml file.

The sessions.xml file provides a simple and flexible way to configure, modify, and troubleshoot the application sessions. Because of these attributes, the sessions.xml file is the preferred way to configure an EclipseLink session.EclipseLink provides graphical toosl to build and edit the sessions.xml file. For information see Creating a Session.

JPA Applications and Session Metadata

For a JPA application, you can express session metadata using JPA annotations, persistence.xml, orm.xml, and EclipseLink JPA annotation and persistence.xml property extensions. The EclipseLink JPA persistence provider interprets all these sources of metadata to create an in-memory EclipseLink session and project at run time.

Using EclipseLink JPA, you also have the option of specifying your metadata using EclipseLink sessions.xml and project.xml while accessing your persistent classes using JPA and an EntityManager. For more information, see What You May Need to Know About EclipseLink JPA Overriding Mechanisms.

Creating Deployment Files for Java Applications

In a Java application, EclipseLink does not use a Java EE container for deployment. Instead, it relies on EclipseLink mechanisms to provide functionality and persistence. The key elements of this type of application are the lack of a Java EE container and the fact that you deploy the application by placing the application JAR file on the classpath.

Java applications require the following deployment files:

• project.xml File
• sessions.xml File

Creating Deployment Files for JavaServer Pages and Servlet Applications

Many designers build EclipseLink applications that use JavaServer Pages (JSP) and Java servlets. This type of design generally supports Web-based applications.

JSP and servlet applications require the following deployment files:

• project.xml File
• sessions.xml File

Creating Deployment Files for Session Bean Applications

Session beans generally model a process, operation, or service and as such, are not persistent. You can build EclipseLink applications that wrap interaction with EclipseLink in session beans. Session beans execute all EclipseLink-related operations on behalf of the client.

This type of design uses JTS and externally managed transactions, but does not incur the overhead associated with persistence applications. Session bean applications also scale and deploy easily.

This section describes the following:

• How to Create Deployment Files for EJB 3.0 Session Bean Applications

How to Create Deployment Files for EJB 3.0 Session Bean Applications

We recommend using JPA annotations and persistence unit properties, or a special-case eclipselink.sessions-xml persistence unit property (see EclipseLink JPA Persistence Unit Properties for Database, Session, and Application Server) in your EJB 3.0 session bean application.

You may also choose to use the project.xml File and sessions.xml File.

For more information, see the following:

• Java Persistence API Overview
• EclipseLink JPA Overview
• Application Development with EclipseLink JPA)

Creating Deployment Files for JPA Applications

See Packaging and Deploying EclipseLink JPA Applications for information on how to create deployment files for your JPA application.

Configuring the weblogic-ejb-jar.xml File for WebLogic Server

Before you deploy a EclipseLink application to Oracle WebLogic Server, you must modify the weblogic-ejb-jar.xml file.

Avoid the weblogic-ejb-jar.xml tags that EclipseLink either does not support or does not require (see What You May Need to Know About Unsupported weblogic-ejb-jar.xml File Tags).

What You May Need to Know About Unsupported weblogic-ejb-jar.xml File Tags

The weblogic-ejb-jar.xml file includes the following tags that EclipseLink either does not support or does not require:

• concurrency-strategy: This tag specifies how Oracle WebLogic Server manages concurrent users for a given bean. Because EclipseLink manages concurrent access internally, it does not require this tag.
  For more information about the EclipseLink concurrency strategy, see Configuring Locking Policy.
• db-is-shared: Because EclipseLink does not make any assumptions about the exclusivity of database access, EclipseLink does not require this tag. EclipseLink addresses multiuser access issues through various locking and refreshing policies.
• delay-updates-until-end-of-tx: EclipseLink always delays updates until the end of a transaction, and does not require this tag.
• finders-load-bean: EclipseLink always loads the bean upon execution of the finder, and does not require this tag.
• pool: EclipseLink does not use a pooling strategy for entity beans. This avoids object-identity problems that can occur due to pooling.
• lifecycle: This element manages beans that follow a pooling strategy. Because EclipseLink does not use a pooling strategy, EclipseLink ignores this tag.
• is-modified-method-name: EclipseLink does not require a bean developer-defined method to detect changes in the object state.
• isolation-level: Because isolation level settings for the cache or database transactions are specified in the EclipseLink project, EclipseLink ignores this tag.
• cache: Because you define EclipseLink cache properties in Workbench, this tag is unnecessary.

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