EclipseLink/UserGuide/JPA/Advanced JPA Development/Performance/Weaving/Weaving POJO Classes

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Weaving POJO Classes

EclipseLink uses weaving to enable the following for POJO classes:

• Lazy loading
• Change tracking
• Fetch groups

EclipseLink weaves all the POJO classes in the JAR you create when you package a POJO application for weaving, as described in Packaging a POJO Application for Weaving, below.

EclipseLink weaves all the classes defined in the persistence.xml file, that is:

• all the classes you list in the persistence.xml file;
• all classes relative to the JAR containing the persistence.xml file if element <exclude-unlisted-classes> is false.

Packaging a POJO Application for Weaving

To package a POJO application for weaving, you create a JAR that contains a sessions.xml file and a persistence.xml file, as described below:

1. Create a sessions.xml file for your application.
   For more information, see Introduction to EclipseLink Sessions.
2. Create a persistence.xml file for your application and reference your sessions.xml file, as the following example shows.
   persistence.xml File for an EclipseLink JPA Application
   

   <persistence>
       <persistence-unit name="appname">
           <exclude-unlisted-classes>false</exclude-unlisted-classes>
           <properties>
   
               <property
                   name="eclipselink.session-name"
                   value="appname-session"
               >
               <property
                   name="eclipselink.sessions-xml"
                   value="sessions.xml"
               >
           </properties>
       </persistence-unit>
   </persistence>
   

3. Create a JAR file that contains your POJO classes, sessions.xml file, and persistence.xml file, as the following example shows.
   Put both the persistence.xml and sessions.xml file in a META-INF directory.
   JAR File for a POJO Application

   appname.jar
       META-INF
           persistence.xml
           sessions.xml
       *.java
   

4. Weave the JAR.
   For more information, see the following:
   • Configuring Dynamic Weaving
   • Configuring Static Weaving

Version: 2.2.0 DRAFT
Other versions...

Static Weaving	About Weaving	Weaving and Java EE Application Servers
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