openjpa-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: EMF JNDI lookup is starting openJPA every time - was: Howto integrate JPA within EJB2.1 session beans?
Date Wed, 28 Feb 2007 02:29:28 GMT
Hi Pinaki,


On Feb 27, 2007, at 5:06 PM, Pinaki Poddar wrote:

> The JNDI spec says:  "the container knows that the application  
> can't change the state of the object."
> How does one tell the container that the JNDI-bound instance is one  
> such 'application immutable' object?
>
>> What we ended up with was implementing the naming.Referenceable  
>> interface
> Did the JDO solution defined its own javax.naming.spi.ObjectFactory  
> to take control of how JNDI-bound instances are created on lookup?

Exactly. See http://svn.apache.org/repos/asf/db/jdo/trunk/fostore20/ 
src/java/org/apache/jdo/impl/fostore/FOStorePMFFactory.java

This is the code that implements ObjectFactory.

And see
http://svn.apache.org/repos/asf/db/jdo/trunk/fostore20/src/java/org/ 
apache/jdo/impl/fostore/FOStorePMF.java

There is code to find an identically-configured PMF in the method  
getPersistenceManagerFactory(Properties).

The final step of connecting the getObjectInstance to the  
getPersistenceManagerFactory(Properties) wasn't done but this is the  
obvious way to do it. In other words, in getObjectInstance, convert  
the StringRefAddrs into Properties and then find the matching  
PersistenceManagerFactory in the map.

Craig


>
>
>
> Pinaki Poddar
> BEA Systems
> 415.402.7317
>
>
> -----Original Message-----
> From: Craig.Russell@Sun.COM [mailto:Craig.Russell@Sun.COM]
> Sent: Tuesday, February 27, 2007 3:32 PM
> To: open-jpa-dev@incubator.apache.org
> Subject: Re: EMF JNDI lookup is starting openJPA every time - was:  
> Howto integrate JPA within EJB2.1 session beans?
>
> We had a similar issue with the JDO Reference Implementation. What  
> we ended up with was implementing the naming.Referenceable  
> interface and writing our own externalization protocols that  
> basically allowed the container to create new instances of our  
> Factory that were actually trivial wrappers that delegated to the  
> real Factory.
>
> So yes, I believe that unless a container "knows" that a bound  
> value is actually sharable (see below), it will generally serialize  
> the instance and then deserialize it for each caller. The way to  
> make this operation perform well (short of telling the container to  
> share
> it) is to implement the Referenceable contracts.
>
> I can drag out more details if there is interest. Or you can look  
> at the implementation of FOStorePMF in the Apache JDO project.
>
> Craig
>
> On Feb 27, 2007, at 9:47 AM, Pinaki Poddar wrote:
>
>>> But maybe something funky is happening with JNDI serializing the
>>> factory and then deserializing it or something.
>>
>> From  J2EE 1.4 spec, page 59 (J2EE.5.2 Java Naming and Directory
>> Interface:
>>
>> In general, lookups of objects in the JNDI java: namespace are
>> required to return a new instance of the requested object every time.
>> Exceptions are allowed for the following:
>> - The container knows the object is immutable (for example,  
>> objects of
>> type java.lang.String), or knows that the application can't change  
>> the
>> state of the object.
>> -The object is defined to be a singleton, such that only one instance
>> of the object may exist in the JVM.
>> -The name used for the lookup is defined to return an instance of the
>> object that might be shared. The name java:comp/ORB is such a name.
>>
>> In these cases, a shared instance of the object may be returned. In
>> all other cases, a new instance of the requested object must be
>> returned on each lookup.
>>
>>
>> Pinaki Poddar
>> BEA Systems
>> 415.402.7317
>>
>>
>> -----Original Message-----
>> From: Patrick Linskey [mailto:plinskey@bea.com]
>> Sent: Monday, February 26, 2007 11:11 PM
>> To: open-jpa-dev@incubator.apache.org
>> Subject: RE: EMF JNDI lookup is starting openJPA every time - was:
>> Howto integrate JPA within EJB2.1 session beans?
>>
>> It should be going through the following code:
>>
>>     public static OpenJPAEntityManagerFactory
>> createEntityManagerFactory
>>         (String jndiLocation, Context context) {
>>         if (jndiLocation == null)
>>             throw new NullPointerException("jndiLocation == null");
>>
>>         try {
>>             if (context == null)
>>                 context = new InitialContext();
>>
>>             Object o = context.lookup(jndiLocation);
>>             return (OpenJPAEntityManagerFactory)
>> PortableRemoteObject.narrow(o,
>>                 OpenJPAEntityManagerFactory.class);
>>         } catch (NamingException ne) {
>>             throw new ArgumentException(_loc.get("naming-exception",
>>                 jndiLocation), new Throwable[]{ ne }, null, true);
>>         }
>>     }
>>
>> I don't see anything in there that would be causing a creation to
>> happen. But maybe something funky is happening with JNDI serializing
>> the factory and then deserializing it or something.
>>
>> Do you have any means of getting a stack from where the creation is
>> happening? It'd be great to get a bit more context about what's going
>> on.
>>
>> -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 J. Prueller [mailto:hans.prueller@gmx.net]
>>> Sent: Saturday, February 24, 2007 10:36 PM
>>> To: open-jpa-dev@incubator.apache.org
>>> Subject: EMF JNDI lookup is starting openJPA every time -
>>> was: Howto integrate JPA within EJB2.1 session beans?
>>>
>>> Hi together, Patrick,
>>>
>>> the code you suggested for doing a helper method that deals with the
>>> EMF JNDI lookup and the EM creating within our J2EE1.4 app basically
>>> works fine, but as you perhaps may remember I asked why the  
>>> method is
>>> called "create":
>>>
>>> EntityManagerFactory myemf =
>>> OpenJPAPersistence.createEntityManagerFactory(strJNDILocation,
>>> (Context)null);
>>>
>>> It seems that the method above really creates a NEW EMF on every
>>> invocation!
>>> I checked the logs of my application and I see the following  
>>> messages
>>> on every invocation of my PersistenceService.getEntityManger()
>>> method (which
>>> does the above lookup and some more ..)
>>>
>>> 2007-02-25 07:27:05,687 : PersistenceService.getEntityManager
>>> : creating a
>>> fresh
>>> , clean EntityManager from JNDI EMF.
>>> 15  lbsims  INFO   [RMI TCP Connection(35)-192.168.0.5]
>>> openjpa.Runtime -
>>> Starti
>>> ng OpenJPA 0.9.7-incubating-SNAPSHOT
>>> 15  lbsims  INFO   [RMI TCP Connection(35)-192.168.0.5]
>>> openjpa.jdbc.JDBC -
>>> Open
>>> JPA will now connect to the database to attempt to determine what
>>> type of databa se dictionary to use.  To prevent this connection in
>>> the future, set your openjp a.jdbc.DBDictionary configuration
>>> property to the appropriate value for your dat abase (see the
>>> documentation for available values).
>>> 15  lbsims  INFO   [RMI TCP Connection(35)-192.168.0.5]
>>> openjpa.jdbc.JDBC -
>>> Usin
>>> g dictionary class
>>> "org.apache.openjpa.jdbc.sql.MySQLDictionary" (MySQL 5.0.27-c
>>> ommunity-nt ,MySQL-AB JDBC Driver mysql-connector-java-5.0.4  
>>> ( $Date:
>>> 2006-10-19
>>>  17:47:48 +0200 (Thu, 19 Oct 2006) $, $Revision: 5908 $ )).
>>> 15  lbsims  INFO   [RMI TCP Connection(35)-192.168.0.5]
>>> openjpa.MetaData -
>>> Found
>>>  1 classes with metadata in 0 milliseconds.
>>>
>>>
>>> It seems that OpenJPA is now bootstrapping everytime I access it.
>>> I am
>>> binding the EMF somewhen at bootstrapping time with
>>>
>>> final EntityManagerFactory emFactory = Persistence
>>> 				.createEntityManagerFactory("lbsims");
>>>
>>> Context ictx = new InitialContext();
>>> ictx.bind(PersistenceService.EMF_JNDI_LOCATION, emFactory);
>>>
>>> The lookup uses the same constants, so the EMF in JNDI should be
>>> found?
>>>
>>> EntityManagerFactory emf = OpenJPAPersistence
>>> 	
>>> .createEntityManagerFactory(EMF_JNDI_LOCATION, (Context) null);
>>>
>>> Any Idea what could be wrong here?
>>>
>>> regards,
>>> HANS
>>>
>>>
>>>> -----Urspr√ľngliche Nachricht-----
>>>> Von: Patrick Linskey [mailto:plinskey@bea.com]
>>>> Gesendet: Freitag, 23. Februar 2007 18:46
>>>> An: open-jpa-dev@incubator.apache.org
>>>> Betreff: RE: TYPO? Howto integrate JPA within EJB2.1 session beans?
>>>> [architecture]
>>>>
>>>> Typo indeed. It should be
>>> OpenJPAPersistence.toBrokerFactory(emf). Sorry
>>>> about that.
>>>>
>>>> -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 J. Prueller [mailto:hans.prueller@gmx.net]
>>>>> Sent: Friday, February 23, 2007 9:43 AM
>>>>> To: open-jpa-dev@incubator.apache.org
>>>>> Subject: RE: TYPO? Howto integrate JPA within EJB2.1 session  
>>>>> beans?
>>>>> [architecture]
>>>>>
>>>>> Patrick,
>>>>>
>>>>> I'm currently trying your tip with a PersistenceService util class
>>>>> doing the lookup of a synchronized entity manager. The problem is
>>>>> that your sample code does not work!
>>>>>
>>>>> in fact the statement
>>>>>
>>>>> final BrokerFactory bf = OpenJPAPersistence.cast(emf);
>>>>>
>>>>> is the problem. the above "cast" does not return a BrokerFactory
>>>>> instance!
>>>>>
>>>>> I am using a 2 days old nightly snapshot 0.9.7 build
>>>>>
>>>>> Where is the problem?
>>>>>
>>>>> Hans
>>>>>
>>>>>> -----Urspr√ľngliche Nachricht-----
>>>>>> Von: Patrick Linskey [mailto:plinskey@bea.com]
>>>>>> Gesendet: Donnerstag, 22. Februar 2007 23:22
>>>>>> An: open-jpa-dev@incubator.apache.org
>>>>>> Betreff: RE: RE: Howto integrate JPA within EJB2.1
>>> session beans?
>>>>>> [architecture]
>>>>>>
>>>>>>> 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.
>>>>>>
>>>>>> OK, I got fed up with that synchronized block. OPENJPA-161
>>>>> tracks the
>>>>>> issue; I've got a patch that I'll submit once some more
>>>>> eyes look at it.
>>>>>>
>>>>>> -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: Patrick Linskey [mailto:plinskey@bea.com]
>>>>>>> Sent: Thursday, February 22, 2007 8:38 AM
>>>>>>> To: open-jpa-dev@incubator.apache.org
>>>>>>> Subject: RE: RE: Howto integrate JPA within EJB2.1 session  
>>>>>>> beans?
>>>>>>> [architecture]
>>>>>>>
>>>>>>>> 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:hans.prueller@gmx.net]
>>>>>>>> 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" <plinskey@bea.com>
>>>>>>>> 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:hans.prueller@gmx.net]
>>>>>>>>>> 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
>>>>>>>>
>>>>>>>
>>>>>
>>>>>
>>>
>>>
>
> Craig Russell
> Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
> 408 276-5638 mailto:Craig.Russell@sun.com P.S. A good JDO? O, Gasp!
>
> ______________________________________________________________________ 
> _
> 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.

Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:Craig.Russell@sun.com
P.S. A good JDO? O, Gasp!


Mime
View raw message