4 Replies Latest reply on Aug 4, 2004 2:34 PM by Erez Efrati

    Synchronization of Stateful Session Bean

    Thomas Fruehbeck Newbie

      Hi,

      I want to use SFSB for a kind of state machine. But a big problem is, that the SFSB is not synchronized, but throws an EJBException - which is correct reg. the specification.

      The hint I found until now was to synchronize the invocations of the SFSB on client side (eg. JSP/Servlet). But unfortnately this doesn't work with multiple clients or multithreaded clients not under my programmatic control.

      Can anyone help me?

        • 1. Re: Synchronization of Stateful Session Bean
          Scott Stark Master

          Change the stateful session interceptor to synchronize calls instead of throwing an exception or add a client interceptor that does the synchronization on the client side.

          • 2. Re: Synchronization of Stateful Session Bean
            Thomas Fruehbeck Newbie

            Thanks for the immediate response!

            My situation unfortunately doesn't provide the second possibility, because the clients are connected via CORBA (SFSB are TIE servants) so there will be no client interceptor stack, isn't it?.
            I really would have liked to implement the client interceptor, because I really like this concept.

            A problem I see with the stateful interceptor is the possibility of deadlock. I had a short experimental hack at the QueuedPessimisticEJBLock (inserting the EntityLockInterceptor in the container interceptor stack) which provides deadlock protection.

            Do you think it's worth while investing in the idea?
            At the moment I don't see far enough to be able to decide if I ever get to the bottom of the Tx-oriented locking.

            I had to remove some consistency checks (eg. regarding the change of transactional context), and so I am afraid that I entered into programmatic states that the code was not intended to cope with.
            I am at the moment stuck with a continuous sequence of "Start wait on TxLock" / "End wait on TxLock" of the two racing threads till the Tx expires - and both get an Exception.

            Regards.

            • 3. Re: Synchronization of Stateful Session Bean
              Thomas Fruehbeck Newbie

              Hi,

              I think I found my error. It seems to work!

              Many thanks for the support.

              Thomas

              • 4. Re: Synchronization of Stateful Session Bean
                Erez Efrati Newbie

                 

                "scott.stark@jboss.org" wrote:
                Change the stateful session interceptor to synchronize calls instead of throwing an exception or add a client interceptor that does the synchronization on the client side.


                How do you do that?

                --Erez