EE JPA container responsibilities

7.9.1 Container Responsibilities

7.9.1 Container Responsibilities

For the management of a transaction-scoped persistence context, if there is no EntityManager already associated with the JTA transaction:

*  The container creates a new entity manager by calling EntityManagerFactory.createEntityManager when the first invocation of an entity manager with PersistenceContextType.TRANSACTION occurs within the scope of a business method executing in the JTA transaction.

*  After the JTA transaction has completed (either by transaction commit or rollback), the container closes the entity manager by calling EntityManager.close. [86] Note that the JTA transaction may rollback in a background thread (e.g., as a result of transaction timeout), in which case the container should arrange for the entity manager to be closed but the EntityManager.close method should not be concurrently invoked while the application is in an EntityManager invocation.
 
The container must throw the TransactionRequiredException if a transaction-scoped persistence context is used and the EntityManager persist, remove, merge, or refresh method is invoked when no transaction is active.

For stateful session beans with extended persistence contexts:

*  The container creates an entity manager by calling EntityManagerFactory.createEntityManager when a stateful session bean is created that declares a dependency on an entity manager with PersistenceContextType.EXTENDED. (See section 7.6.3).

*  The container closes the entity manager by calling EntityManager.close after the stateful session bean and all other stateful session beans that have inherited the same persistence context as the entity manager have been removed.

*  When a business method of the stateful session bean is invoked, if the stateful session bean uses container managed transaction demarcation, and the entity manager is not already associated with the current JTA transaction, the container associates the entity manager with the current JTA transaction and, if the persistence context is of type SynchronizationType.SYNCHRONIZED, the container calls EntityManager.joinTransaction. If there is a different persistence context already associated with the JTA transaction, the container throws the EJBException.

*  When a business method of the stateful session bean is invoked, if the stateful session bean uses bean managed transaction demarcation and a UserTransaction is begun within the method, the container associates the persistence context with the JTA transaction and, if the persistence context is of type SynchronizationType.SYNCHRONIZED, the container calls EntityManager.joinTransaction.

The container must throw the IllegalStateException if the application calls EntityManager.close on a container-managed entity manager.

When the container creates an entity manager, it may pass a map of properties to the persistence provider by using the EntityManagerFactory.createEntityManager(Map map) method. If properties have been specified in the PersistenceContext annotation or the persistence-context-ref deployment descriptor element, this method must be used and the map must include the specified properties.

If the application invokes EntityManager.unwrap(Class<T> cls), and the container cannot satisfy the request, the container must delegate the unwrap invocation to the provider’s entity manager instance.


[86] The container may choose to pool EntityManagers: it instead of creating and closing in each case, it may acquire one from its pool and call clear() on it.