Deploying a JPA application to the Liberty profile

To enable the Liberty profile to support an application that uses the Java™ Persistence API (JPA), you add the jpa-2.0 feature to the server.xml file. You also need to define persistence contexts and persistence units, and configure access to the entity manager and entity manager factory.

• Add the jpa-2.0 feature to the server.xml file.
• Add persistence context and persistence unit definitions to the web.xml file.
  For example:

  <persistence-context-ref>
      <persistence-context-ref-name>example/em</persistence-context-ref-name>
      <persistence-unit-name>ExamplePersistenceUnit</persistence-unit-name>
  </persistence-context-ref> 
  
  <persistence-unit-ref>
      <persistence-unit-ref-name>example/emf</persistence-unit-ref-name>
      <persistence-unit-name>ExamplePersistenceUnit</persistence-unit-name>
  </persistence-unit-ref>

• Configure access to the entity manager.
  For example:

  Context ctx = new InitialContext();
  UserTransaction tran = (UserTransaction) ctx.lookup("java:comp/UserTransaction");
  tran.begin();
  EntityManager em = (EntityManager) ctx.lookup(java:comp/env/example/em");
  Thing thing = new Thing();
  em.persist(thing);
  tran.commit();

• Configure access to the entity manager factory.
  For example:

  Context ctx = new InitialContext();
  EntityManagerFactory emf = (EntityManager) ctx.lookup(java:comp/env/example/emf");
  EntityManager em = emf.createEntityManager();
  EntityTransaction tx = em.getTransaction();
  tx.begin();
  Thing thing = new Thing();
  em.persist(thing);
  tx.commit();
  int id = thing.getId();
  em.close();