Dynamically undeploying MDBs

Question

          Hi,
          I am using Weblogic 6.1 SP4 - Integrating with MQ5.2 using IBM MQ Classes.
          I have an MDB which points to a MQ Queue. MDB takes the message and delegates
          to specific Java Classes which parse the XML (body of the message) into Java Objects
          and save them into database.
          I have implemented Container Managed transactional MDBs. Before processing the
          message I am checking to see if the database connection is available. If the
          database connection is not available, I am rolling back the message into the Queue.
          The problem is that this is getting into a loop, till the database connection
          is available. (MDB picks up the message and checks up for database connectivity
          and rolls back into the queue).
          The solution that I have thought of doing is to check upto 5 times (just a count
          I have decided), after which I will undeploy the MDBs dynamically. Then I will
          start a new Thread (Thread class) which will check if the database connection
          is available and once the connection is available, I will redeploy the MDB to
          process the message again.
          I have following questions here:
          (1) How to dynamically undeploy & re-deploy MDB
          (2) How can I check Redelivered Count. I know that I can use Message.getJMSRedelivered
          (), which will return me a boolean stating the message is redelivered. If I
          can't check for Redelivered count, then if getJMSRedelivered() is "true", then
          I will undeploy the MDB.
          (3) Will there be any issues/problems in the solution discussed above.
          Thanks in advance for any help.
          Regards,
          Venkatesan.
          

Answer 1

As I wrote below, I think there is a way, but I don't
          know how. For programmatically undeploying the MDB,
          I suggest posting your needs to the "ejb" newsgroup, which has
          more experience in this area. (I mentioned this already
          in another part of this email thread.)
          Tom
          Sastry wrote:
          > Hi Tom,
          >
          > Is there any way to use weblogic 7.0 JMX API's to suspend a MDB so that it won't
          > process any messages from the queue until the next destination like oracle database
          > connection is up and running.
          >
          > Thanks
          > Sastry
          >
          > Tom Barnes <[email protected]> wrote:
          >
          >>9.0 - I don't know the official release date, but I
          >>imagine its in the latter half of 2004. For now,
          >>there is undeploying the MDBs, or shutting down JMS.
          >>
          >>Tom
          >>
          >>Mikhail Stolpner wrote:
          >>
          >>
          >>>Yes. Exactly.
          >>>What next release do you mean? Is it 8.1SP2 or 9.0?
          >>>
          >>>Thank you very much,
          >>>Mikhail
          >>>
          >>>"Tom Barnes" <[email protected]> wrote in message
          >>>news:[email protected]...
          >>>
          >>>
          >>>>Clarification. You can pause "produces", but not "consumes",
          >>>>using the console or programmatically via JMX.
          >>>>I assumed you meant to pause "consumes".
          >>>>
          >>>>Tom Barnes wrote:
          >>>>
          >>>>
          >>>>
          >>>>>Hi Mikhail,
          >>>>>
          >>>>>There is no direct way. In 7.0 and later you can
          >>>>>programmatically shutdown
          >>>>>the entire JMS server, while leaving the WL server up,
          >>>>>by setting the JMS server mbean's "target"
          >>>>>field to null.
          >>>>>
          >>>>>Note that you can have multiple JMS server's per WL
          >>>>>server.
          >>>>>
          >>>>>Tom
          >>>>>
          >>>>>P.S. A rich featured pause capability is planned
          >>>>>for the next release. This includes the ability
          >>>>>to pause an MDB, as well as an entire destination
          >>>>>in various ways.
          >>>>>
          >>>>>Mikhail Stolpner wrote:
          >>>>>
          >>>>>
          >>>>>
          >>>>>>Hi Tom,
          >>>>>>
          >>>>>>Do you know if there is a way to programmatically pause Weblogic
          >>
          >>Queue?
          >>
          >>>>>>Thanks,
          >>>>>>Mikhail
          >>>>>>
          >>>>>>"Tom Barnes" <[email protected]> wrote in message
          >>>>>>news:[email protected]...
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>Hi,
          >>>>>>>
          >>>>>>>A "redelivered count" requires a vendor extension - JMS does
          >>>>>>>not provide one. Check the MQ doc to see if there is one.
          >>>>>>>
          >>>>>>>Another option is programmatically pause MQ - I'm not sure
          >>>>>>>if there is a way to do this. Again - check the MQ doc.
          >>>>>>>
          >>>>>>>Another option is to simply block the MDB in a try/sleep()
          >>>>>>>retry loop until the database connection comes back up.
          >>>>>>>
          >>>>>>>As for programmatically undeploying the MDB, I suggest
          >>>>>>>posting your needs to the "EJB" newsgroup, which has
          >>>>>>>more experience in this area.
          >>>>>>>
          >>>>>>>Tom
          >>>>>>>
          >>>>>>>Venkatesan wrote:
          >>>>>>>
          >>>>>>>
          >>>>>>>
          >>>>>>>
          >>>>>>>>Hi,
          >>>>>>>>I am using Weblogic 6.1 SP4 - Integrating with MQ5.2 using IBM
          >>
          >>MQ
          >>
          >>>>>>
          >>>>>>Classes.
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>I have an MDB which points to a MQ Queue. MDB takes the message
          >>
          >>and
          >>
          >>>>>>
          >>>>>>delegates
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>to specific Java Classes which parse the XML (body of the message)
          >>>
          >>>into
          >>>
          >>>
          >>>>>>Java Objects
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>and save them into database.
          >>>>>>>>I have implemented Container Managed transactional MDBs. Before
          >>>>>>
          >>>>>>
          >>>>>>processing the
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>message I am checking to see if the database connection is available.
          >>>>>>
          >>>>>>
          >>>>>>If the
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>database connection is not available, I am rolling back the message
          >>>>>>>>into
          >>>>>>
          >>>>>>
          >>>>>>the Queue.
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>The problem is that this is getting into a loop, till the database
          >>>>>>
          >>>>>>
          >>>>>>connection
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>is available. (MDB picks up the message and checks up for database
          >>>>>>
          >>>>>>
          >>>>>>connectivity
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>and rolls back into the queue).
          >>>>>>>>The solution that I have thought of doing is to check upto 5 times
          >>>>>>>>(just
          >>>>>>
          >>>>>>
          >>>>>>a count
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>I have decided), after which I will undeploy the MDBs dynamically.
          >>>>>>>>Then
          >>>>>>
          >>>>>>
          >>>>>>I will
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>start a new Thread (Thread class) which will check if the database
          >>>>>>
          >>>>>>
          >>>>>>connection
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>is available and once the connection is available, I will redeploy
          >>>
          >>>the
          >>>
          >>>
          >>>>>>MDB to
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>process the message again.
          >>>>>>>>
          >>>>>>>>I have following questions here:
          >>>>>>>>
          >>>>>>>> (1) How to dynamically undeploy & re-deploy MDB
          >>>>>>>> (2) How can I check Redelivered Count. I know that I can use
          >>>>>>
          >>>>>>
          >>>>>>Message.getJMSRedelivered
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>(), which will return me a boolean stating the message is
          >>>
          >>>redelivered.
          >>>
          >>>
          >>>>>>If I
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>can't check for Redelivered count, then if getJMSRedelivered()
          >>
          >>is
          >>
          >>>>>>
          >>>>>>"true", then
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>I will undeploy the MDB.
          >>>>>>>> (3) Will there be any issues/problems in the solution discussed
          >>>>>>
          >>>>>>
          >>>>>>above.
          >>>>>>
          >>>>>>
          >>>>>>
          >>>>>>>>Thanks in advance for any help.
          >>>>>>>>
          >>>>>>>>Regards,
          >>>>>>>>Venkatesan.
          >>>>>>>>
          >>>>>>>>
          >>>>>>>
          >>>
          >