AQ - MDB Concurrency issue

Question

          Hi,
          I have written a java startup class to bind the AQ connection factory and AQ queue
          to the JNDI tree of a WebLogic server and have deployed an MDB on WebLogic to
          listen to the AQ.
          (I have used Eric Ma's code as an example.)
          The MDB is working fine and is continuously listening to the Oracle AQ hosted
          on a Solaris box.
          But, the problem is that no matter how many instances of the MDB are deployed
          in the pool, onMessage() method of just one MDB is called repeatedly i.e. only
          single instance of MDB consumes AQ messages no matter how many instance are in
          pool or how may threads are available in queue.
          The MDB is deployed on WebLogic server 7 sp 4 on a Win 2000 box and has 5 inctances
          in the pool. I am using OCI driver for the connection to the AQ. Oracle 9.2.0
          is on a Solaris box and the IP address and the machine name of the JMS client
          (i.e. windows machine) is included in the /etc/hosts of the Solaris box.
          Any help towards achieving concurrency in consumption of messages from Oracle
          AQ would be great.
          Regards,
          Diptanshu
          

Answer 1

          I don't think that would help. Coz that means that the message is consumed once
          by each of the consumers. That's not what I want. I wish to instance 2 of MDB
          to read remaining messages from AQ, when instance 1 is busy reading a message
          and processing it.
          One option is to use an MDB as a Façade and then just to post it to an internal
          queue (not AQ) to be picked up for other MDBs for further processing. But, then
          this creates a bottleneck in the form of a single listening point between the
          Façade & the AQ.
          Any better suggestions are welcome.
          Regards,
          Diptanshu
          "Eric Ma" <[email protected]> wrote:
          >
          >Does making AQ a multi-consumer queue help?
          >
          >Eric
          >
          >"Diptanshu Parui" <[email protected]> wrote:
          >>
          >>Hi,
          >>
          >>I have written a java startup class to bind the AQ connection factory
          >>and AQ queue
          >>to the JNDI tree of a WebLogic server and have deployed an MDB on WebLogic
          >>to
          >>listen to the AQ.
          >>(I have used Eric Ma's code as an example.)
          >>
          >>The MDB is working fine and is continuously listening to the Oracle
          >AQ
          >>hosted
          >>on a Solaris box.
          >>
          >>But, the problem is that no matter how many instances of the MDB are
          >>deployed
          >>in the pool, onMessage() method of just one MDB is called repeatedly
          >>i.e. only
          >>single instance of MDB consumes AQ messages no matter how many instance
          >>are in
          >>pool or how may threads are available in queue.
          >>
          >>The MDB is deployed on WebLogic server 7 sp 4 on a Win 2000 box and
          >has
          >>5 inctances
          >>in the pool. I am using OCI driver for the connection to the AQ. Oracle
          >>9.2.0
          >>is on a Solaris box and the IP address and the machine name of the JMS
          >>client
          >>(i.e. windows machine) is included in the /etc/hosts of the Solaris
          >box.
          >>
          >>Any help towards achieving concurrency in consumption of messages from
          >>Oracle
          >>AQ would be great.
          >>
          >>Regards,
          >>Diptanshu
          >