Patrick,
thank you for that tip. To be true, I was not aware of lifecycle related
problems between my SLSBs and JPA - thank you for that hint. As I want to avoid
working with ThreadLocal (simply because I didn't work with ThreadLocals yet) I
would prefer the JNDI-EMF based approach.
If I understand it correct, I "just" have to bind the EMF onserver startup like.
context.bind("my/jndi/name/for/emf",myEMFVariable);
I would be interested what the code for the PersistenceService class does:
//does the statement below again create a NEW EMF or ist this
//just a lookup in the jndi-tree? but why is it called "Create"
//and not get?
EntityManagerFactory emf = OpenJPAPersistence
.createEntityManagerFactory(
"your/EMF/JNDI/location", (Context) null);
//why do i have to cast the EMF to a brokerfactory now? I
//would guess the "broker" is something like a more abstract
//concept of entitymanager(factory)?
//why do I have to create a new broker/entitymanager this way?
//is this because I have to "synchronize" the SLSBs transaction
//context with the newly created entitymanager?
BrokerFactory bf = OpenJPAPersistence.cast(emf);
Broker b = bf.newBroker(
bf.getConfiguration().getConnectionUserName(),
bf.getConfiguration().getConnectionPassword(),
true, // the broker is part of a JTA managed tx
bf.getConfiguration().getConnectionRetainModeConstant(),
true); // look for an existing Broker on the tx
broker.setAutoDetach(AutoDetach.DETACH_CLOSE, true);
broker.setAutoDetach(AutoDetach.DETACH_ROLLBACK, true);
broker.setDetachedNew(false);
return OpenJPAPersistence.toEntityManager(b);
}
So if understand that right I just would have to call
PersistenceService.getEntitymanager();
in every SLSB method (NOT in ejbCreate) when needed? fine. I really appreciate
your help - it's quite complex to integrate JPA into an existing Java2EE 1.4
AppServer environment.. *puh*
regards
Hans
-------- Original-Nachricht --------
Datum: Wed, 21 Feb 2007 08:43:20 -0800
Von: "Patrick Linskey" <[EMAIL PROTECTED]>
An: open-jpa-dev@incubator.apache.org
CC:
Betreff: RE: Howto integrate JPA within EJB2.1 session beans? [architecture]
> Another common technique is to get an EMF into JNDI, either by using a
> startup hook or deploying OpenJPA as a JCA RAR.
>
> Are you looking to integrate OpenJPA with your current managed
> transaction? If so, I'd be careful about creating an EM in ejbCreate(),
> as its lifecycle is related to the life of the SLSB, not to the
> transactional context (the SLSB might be pooled). So, I'd just try to
> get the EMF into JNDI when the server starts (creating EMFs is slow).
> Then, you could avoid having to use your own ThreadLocal work by using
> the internal OpenJPA BrokerFactory APIs:
>
> public class PersistenceService {
> public static EntityManager getEntityManager() {
> EntityManagerFactory emf = OpenJPAPersistence
> .createEntityManagerFactory(
> "your/EMF/JNDI/location", (Context) null);
> BrokerFactory bf = OpenJPAPersistence.cast(emf);
> Broker b = bf.newBroker(
> bf.getConfiguration().getConnectionUserName(),
> bf.getConfiguration().getConnectionPassword(),
> true, // the broker is part of a JTA managed tx
> bf.getConfiguration().getConnectionRetainModeConstant(),
> true); // look for an existing Broker on the tx
>
> // do some JPA configuration setup. Logic stolen from
> // EntityManagerFactoryImpl.
> broker.setAutoDetach(AutoDetach.DETACH_CLOSE, true);
> broker.setAutoDetach(AutoDetach.DETACH_ROLLBACK, true);
> broker.setDetachedNew(false);
>
> return OpenJPAPersistence.toEntityManager(b);
> }
> }
>
> Meanwhile, we really should add a couple new OpenJPAPersistence /
> OpenJPAEntityManagerFactory methods to help out with this type of
> bootstrapping.
>
> -Patrick
>
> --
> Patrick Linskey
> BEA Systems, Inc.
>
> _______________________________________________________________________
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>
> > -----Original Message-----
> > From: Hans Prueller [mailto:[EMAIL PROTECTED]
> > Sent: Wednesday, February 21, 2007 1:02 AM
> > To: open-jpa-dev@incubator.apache.org
> > Subject: Howto integrate JPA within EJB2.1 session beans?
> > [architecture]
> >
> > Hi together,
> >
> > I'm sorry for bothering you with numerous basic questions
> > regarding OpenJPA and its usage but I have to migrate
> > existing CMP EJBs to migrate within short time to OpenJPA as
> > we're having stability issues with the current CMP engine.
> >
> > One last question I'd like to ask is regarding the
> > recommended architecture of using OpenJPA within EJB2.1
> > Stateless sessino beans:
> >
> > I need to work with persistence i.e. the EntityManager
> > throughout all the session beans methods so my idea is to:
> >
> > - create a EntityManagerFactory in the ejbCreate() method of the SLSB
> > - and also create the EntityManager itself in the
> > ejbCreeate() method and store it as a member variable of the SLSB
> > - this would allow easy access within the SB's methods by
> > just using the already initialized entity manager varialbe
> > em.createNamedQuery() .. etc. etc.
> > - clean up should be performed in the ejbRemove() method of the SLSB
> >
> > I think doing so will allow migratino to openJPA with less
> > work than doing the whole lookup procedure in every method
> > separately.
> >
> > what do you think? are there any pitfalls i've overlooked?
> >
> > thank you for your ideas!
> >
> > regards
> > Hans
> > --
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