Information on the Weblogic JMS behaviour

Question

          Hi,
          The WL(5.1,SP6) JMS specification says
          "A Session created with CLIENT_ACKNOWLEDGE relies on the client to call an acknowledge
          method on a received message. Once this method is called, the Session acknowledges
          all messages received since the last acknowledgement. This allows the client to receive
          and process a batch of messages and then acknowledge them all with one call."
          This means that if there are messages m1,m2,m3 in the queue, I can receive all the
          messages and by acknowledging the third message, i acknowledge the other two.
          My requirement is that I should not lose any messages. So is there any way i can
          preserve the other two in the Queue.
          Thanks
          Kiran
          

Answer 1

Hi Kiran,
          See in-line.
          Kiran Pratap wrote:
          > Hi,
          >
          > The WL(5.1,SP6) JMS specification says
          > "A Session created with CLIENT_ACKNOWLEDGE relies on the client to call an acknowledge
          > method on a received message. Once this method is called, the Session acknowledges
          > all messages received since the last acknowledgement. This allows the client to receive
          > and process a batch of messages and then acknowledge them all with one call."
          >
          > This means that if there are messages m1,m2,m3 in the queue, I can receive all the
          > messages and by acknowledging the third message, i acknowledge the other two.
          >
          > My requirement is that I should not lose any messages. So is there any way i can
          > preserve the other two in the Queue.
          >
          You are not losing messages - your app has seen them. But anyway, there is no
          simple way to do this. For a couple of ideas, check out
          http://e-docs.beasys.com/wls/docs61/faq/jms.html#252701
          (I'm not sure if WL 5.1 supports suspending transactions, so the transactional approach
          may not work...)
          FYI: Just to make the issue anti-intuitive ;-), the JMS spec requires that all messages
          the session
          has received, not just the messages before the given message, be acknowledged when a
          message is acknowledged. This was determined in a clarification with javasoft.
          WebLogic 5.1 does not do this but continues to do "ack-prev". WebLogic 6.x+ does
          "ack-all",
          but is tunable on the connection factory (acknowledge-all vs. acknowledge-prev option),
          the WL 6.x legacy default connection factories (from 5.1) also do "ack-prev".
          Tom
          >
          > Thanks
          > Kiran