Java Reference
In-Depth Information
Persistence context synchronization
BeforeJPA2.1,thecontainer-managedpersistencecontextwasautomaticallyjoined
to the current transaction, and any update made to the persistence context was
propagated to the underlying resource manager. With the new specification, it is now
possible to have a persistence context that will not be automatically enlisted in any
JTA transaction. This can be done by simply creating a container-managed entity
manager of synchronization type
SynchronizationType.UNSYNCHRONIZED
as
shown in the following code.
Creation and enlistment of a
SynchronizationType.UNSYNCHRONIZED
persist-
ence context:
@Stateless
@LocalBean
public class MySessionBean {
/* Creation of an entity manager for
* unsynchronized persistence context
*/
@PersistenceContext(synchronization =
SynchronizationType.UNSYNCHRONIZED)
EntityManager em;
public void useUnsynchronizedEntityManager(){
//enlisting of an unsynchronized
persistence context
em.joinTransaction();
//...
}
}
In the preceding code, you will notice that we called the
EntityMan-
ager.joinTransaction()
method; this is justified by the fact that a persistence
context of type
SynchronizationType.UNSYNCHRONIZED
is enlisted in a JTA
transaction only after calling the
EntityManager.joinTransaction()
method,
and after a commit or rollback, the
SynchronizationType.UNSYNCHRONIZED
