Hi,

we are using Hibernate 2.1.2 with JBoss 3.2.1. The project uses EntityBeans as persistence layer. For some new functions we want to use Hibernate.
How we use it: The client (other SessionBean, Servlet, JUnitEJB Test) calls a method on a stateless facade-SessionBean. This facade works with stateful SessionBeans (Session for EntityBeans) and/or with hibernate objects and may also call other facades. The hibernate objects don't only have getters and setters, they also have some methods that perform some logic (for example dont get all associated objects but the objects that have a special attribute).
We use the ThreadLocal pattern and the HibernateSession. If I use the Hibernate objects directly it works perfect. I open the Session with HibernateSession.openSession(), do some work and call HibernateSession.closeSession().
But if we are using the facade Session Beans we have the same problem like in this thread http://forum.hibernate.org/viewtopic.php?t=77.

20:25:12,263 INFO [TxConnectionManager$TxConnectionEventListener] throwable from unregister connection
java.lang.IllegalStateException: Trying to return an unknown connection1! org.jboss.resource.adapter.jdbc.WrappedConnection@2b7632
at org.jboss.resource.connectionmanager.CachedConnectionManager.unregisterConnection(CachedConnectionManager.java:264)

We placed the Hibernate.openSession() and Hibernate.closeSession() calls in all Methods of the facade Bean. Do I have to open a Session in every method that works with hibernate objects (that only calls a getter)? Or is the facade the wrong place to open the Session? Should the client do this?

Opening and closing the session in the facade sounds pretty reasonable to me, as long as it gets opened once, and closed once :) so if your facade does not call the facade again it should not be a problem.

The problem is, that there are many facades, that sometimes call other facades to do some work. After some calls over SessionBeans JBoss closes "a unknown connection" for me.
Now I am using Session.currentSession in every Method that uses Hibernate (this is bad - but it works).
The Session-per-Transaction Pattern would be the best solution, but I don't know how to implement this without Spring. I there a way to do this?

And I am also closing the Session in this Method ;-)

You can try the reference counting version of TLS in the wiki - it is not very safe, but it might work. You can also use a JBoss interceptor for managing the session, I am currently working on this, if you want I can send you the source in advance (send me an email)

I prefer to live without EJB and I do not use this way, but I hope it must be a good one:

1. Use stateful bean as facade.
2. Implement transaction synchronization callback interface.
3. Demarcate transactions on client, it can be a filter or commant dispacher (transaction per request and bean reference is stored in any thread scope attribute like threadlocal, request parameter or method parameter ).
4. Close session/connection at the end of transaction.

You do not need any transaction demarcation and threadlocals on server in this case, session can be stored in field. I think it must be a good choise for scalable transactional systems/applications.

thx for your ideas,

I will try them next week.

Hi,

This may be of interest/help:

https://sourceforge.net/forum/forum.php ... _id=250340

Justin