> If I understand it correct, I "just" have to bind the EMF
> onserver startup like.
>
> context.bind("my/jndi/name/for/emf",myEMFVariable);
Yep.
> //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);
It's just a lookup. I'm not sure why it's called 'create'. Anyone?
> //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?
Yes -- our current OpenJPAPersistence EM lookup methods all create new
EMs. The broker code will look up one associated with the current
transaction, which is what you're looking for.
Unfortunately, that means that we're using a synchronized block during
the lookup. If it looks like EM lookup is a scalability issue for your
app, do let us know -- it would be pretty straightforward to replace the
synchronized block with a concurrent map.
> So if understand that right I just would have to call
>
> PersistenceService.getEntitymanager();
>
> in every SLSB method (NOT in ejbCreate) when needed? fine.
Yep.
> I really appreciate your help - it's quite complex to integrate
> JPA into an existing Java2EE 1.4 AppServer environment.. *puh*
Yes -- sorry about that. We should at least be creating better-designed
helper methods in OpenJPA to help out with this.
One alternative, of course, is to use Spring 2, which does a pretty good
job of JPA bootstrapping.
-Patrick
--
Patrick Linskey
BEA Systems, Inc.
_______________________________________________________________________
Notice: This email message, together with any attachments, may contain
information of BEA Systems, Inc., its subsidiaries and affiliated
entities, that may be confidential, proprietary, copyrighted and/or
legally privileged, and is intended solely for the use of the individual
or entity named in this message. If you are not the intended recipient,
and have received this message in error, please immediately return this
by email and then delete it.
> -----Original Message-----
> From: Hans Prueller [mailto:[EMAIL PROTECTED]
> Sent: Thursday, February 22, 2007 4:36 AM
> To: open-jpa-dev@incubator.apache.org;
> open-jpa-dev@incubator.apache.org
> Subject: Re: RE: Howto integrate JPA within EJB2.1 session
> beans? [architecture]
>
> 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.
> >
> >
> ______________________________________________________________
> _________
> > Notice: This email message, together with any attachments,
> may contain
> > information of BEA Systems, Inc., its subsidiaries and
> affiliated
> > entities, that may be confidential, proprietary,
> copyrighted and/or
> > legally privileged, and is intended solely for the use of
> the individual
> > or entity named in this message. If you are not the
> intended recipient,
> > and have received this message in error, please immediately
> return this
> > by email and then delete it.
> >
> > > -----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
> > > --
> > > "Feel free" - 5 GB Mailbox, 50 FreeSMS/Monat ...
> > > Jetzt GMX ProMail testen: www.gmx.net/de/go/mailfooter/promail-out
> > >
>
> --
> "Feel free" - 5 GB Mailbox, 50 FreeSMS/Monat ...
> Jetzt GMX ProMail testen: www.gmx.net/de/go/mailfooter/promail-out
>
