8 Configuring the Persistence Provider in Oracle WebLogic Server

Setting the Default Provider for the Domain

Unless you specify otherwise, TopLink is used as the default persistence provider for a WebLogic Server domain. The default provider is used for any entities in an application that are not configured to use a different persistence provider. The default provider is used for both injected and application-managed entity managers and factories.

You can set the default provider in the WLS Administration Console or by directly setting JPAMBean.DefaultJPAProvider. In the Administration Console, the options are Oracle TopLink or Oracle Kodo.

For instructions on setting the default through the Administration Console, see "Configure the Default JPA Persistence Provider" in Oracle WebLogic Server Administration Console Help.

If you change the default provider, you must do the following for any deployed applications that do not specify a JPA provider:

• Restart applications that use application-managed entity manager factories.

• Redeploy applications that use injected entity manager factories or entity managers.

Specifying the Persistence Provider in an Application

A persistence provider specified in an application takes precedence over the default provider set for the WebLogic Server domain.

You can set the provider to use in the following ways:

• Specify the provider in the <provider> element for a persistence unit in the persistence.xml file, for example:

   <persistence-unit name="example">
      <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
  ...
    </persistence-unit>
  

• Specify the provider in the javax.persistence.provider property passed to the Map parameter of the javax.persistence.Persistence.createEntityManagerFactory(String, Map) method.

Using JPA 1.0 APIs

You cannot use any JPA 2 APIs with Kodo. Because Kodo supports only JPA 1, trying to use any JPA 2 APIs will generate an error.

Using persistence-configuration.xml

The Kodo persistence-configuration.xml descriptor is valid only when Kodo is the persistence provider. If you include a persistence-configuration.xml in an application that uses injection and you do not specify Kodo as the persistence provider, the persistence-configuration.xml descriptor is ignored and a warning is issued.

Updating Applications to Overcome Conflicts with JPA 2.0

Kodo is based on open-source OpenJPA 1.x, the JPA 1.0 framework and provider from the Apache Foundation. Although JPA 1.0 is upwardly compatible with JPA 2.0, JPA 2.0 introduced some methods to existing JPA interfaces that conflict with existing signatures in the OpenJPA interfaces used in Kodo. These conflicts arise because the OpenJPA interfaces extend the JPA interfaces that contain the methods that are revised in JPA 2.0.

These conflicts could cause problems with applications that use Kodo as the persistence provider, because the JPA 2.0 jar (rather than the JPA 1.0 jar) is on the WebLogic Server classpath.

To prevent these conflicts, two methods have been changed in the OpenJPA interfaces that ship with Kodo in WebLogic Server 12c and later. The OpenJPA methods that cause the conflict are:

• public <T> T OpenJPAEntityManager.detach(T pc)

  The above method conflicts with the following JPA 2.0 method in the EntityManager interface:

  public void detach(Object)

• public Properties OpenJPAEntityManagerFactory.getProperties()

  The above method conflicts with the following JPA 2.0 method in the EntityManagerFactory interface:

  public Map<String, Object> getProperties()

The new signatures are:

• public <T> T OpenJPAEntityManager.detachCopy(T pc)

• public Map<String, Object> OpenJPAEntityManagerFactory.getProperties()

• public Properties OpenJPAEntityManagerFactory.getPropertiesAsProperties()

The first two new signatures follow the changes made in OpenJPA 2.x to address these same conflicts. These signature changes do not alter the semantics of the methods. The getPropertiesAsProperties method is provided as a convenience to application developers who do not want to accept the different return type of the redesigned getProperties method. However, the method getPropertiesAsProperties is not currently in the OpenJPA 2.x interface.

Because of these changes, you should update any applications that use these methods and recompile them with the Kodo OpenJPA 1.0 jar (org.apache.openjpa_n.jar) and the JPA 1 jar (javax.persistence_n.jar) that are shipped with WebLogic Server 12c (or later). This will prevent the old method signatures from being used. After recompiling and deploying, the applications will run without change in behavior.

Applications that use Kodo/JDO are not affected by the conflicts described above. Therefore, you do not have to modify or recompile them.