EclipseLink/Examples/JPA/Migration/TopLinkEssentials

This how-to discusses how a user can migrate to using EclipseLink JPA from TopLink Essentials

Persistence.xml

Persistence Provider

Modify the persistence provider from

  <provider>oracle.toplink.essentials.PersistenceProvider</provider>

or

  <provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>

to

  <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>

Properties

When migrating the Persistence.xml the primary change in the persistence unit properties is converting from using "toplink.*" to "eclipselink.*"

target-server

Verify in particular that you have the eclipselink.target-server property set - especially if you are migrating from TopLink Essentials to EclipseLink - where the provider and target-server were defaulted.

• 1) Check that your datasource is configured in transactional mode - usually the default.
• 2) Check your persistence.xml has a target-server property - this will affect transactions.
  • Note: by default GlassFish V2 would have defaulted this "target-server" value when using TopLink Essentials because that persistence provider is the one loaded by default - When using the EclipseLink JPA provider.

You will need to specify target-server it in order to get server platform specific functionality surrounding a transaction manager acquire using "java:appserver/TransactionManager" in the SunAS9TransactionController.

    <property name="eclipselink.target-server" value="SunAS9"/>

• 3) Other things to verify
  • 3a) If you check out the Glassfish V2 quickstart web tutorial, it is using the same persistence.xml format as your example. EclipseLink JPA on GlassFish Web Quickstart Tutorial
  • 3b) To view a similar stateless session bean that uses an injected persistence unit, see the following code - notice that the em.persist() calls have no wrapper transaction calls.
  • See
    • http://dev.eclipse.org/svnroot/rt/org.eclipse.persistence/trunk/examples/org.eclipse.persistence.example.jpa.server.weblogic.enterpriseEJB/ejbModule/org/eclipse/persistence/example/jpa/server/business/ApplicationService.java
  • 3c) Note 1: if you are using a JTA datasource with a stateless session bean then you should not be managing your transactional state using begin or commit - the container will handle the transaction for you.
  • 3d) Note 2: The attribute TransactionAttributeType.REQUIRED is the default state of the @TransactionAttribute annotation - so it does not change container managed behavior in this example.
  • 3e) Note 3: If you are overriding default container managed transactions by specifying TransactionAttributeType at the class context level then verify that your @TransactionManagement annotations on every method are ok.
  • 3f) Note 4: Verify that you have not changed the default TRANSACTION value for PersistenceContextType.EXTENDED in your client servlet or bean of the stateless session bean - or your transaction will extend beyond a single call to the SSB.
  • 3g) Note 5: Depending on how your datasource is setup - If you are creating the datasource on the embedded tomcat servlet container and not on then be aware that you will require a session customizer to change the lookupType' on the JTA connector to JNDIConnector.STRING_LOOKUP
    • see
    • http://wiki.eclipse.org/EclipseLink/Examples/JPA/Tomcat_Web_Tutorial#Session_Customizer

ORM.XML

TopLink Essentials uses the JPA 1.0 defined orm.xml schema and thus is compatible with EclipseLink. The only content changes that should be made is conversion of any query hints used in the configuration.

Java API

Query Hints

• Java code: customer PU properties and query hints
  • Use of EclipseLink native API where TLE native API was used

• Side-effects of the migration
  • Change from default access type when using ORM.XML

Using the Package Rename Utility

See Package Renamer