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| Trigger message consumption |
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| Vin |
 Posted: Fri Jul 12, 2002 2:20 pm Post subject: Trigger message consumption |
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Master
Joined: 25 Mar 2002
Posts: 212
Location: India
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| We have an interesting situation here. I'm using triggering for one of our applications and was wondering about a few things. When my application gets the message after being triggered and for some reason fails to process the message retrieved from the queue, that message is essentially lost right? Is there a way that I can put the message back on the Queue if the trigerred process fails so that when my app is backit can process the message again? How can I do this using MQJMS? The platform we are using is Solaris, messages are sent from the mainframe. Any ideas? Thanks. |
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| bduncan |
| Posted: Fri Jul 12, 2002 3:07 pm Post subject: |
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Padawan
Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley
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If you do your MQGET under syncpoint, then if you application dies before committing the removal of the message from the queue, it should be rolled back automatically and be ready for processing when another application is triggered.
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Brandon Duncan
IBM Certified MQSeries Specialist
MQSeries.net forum moderator |
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| PeterPotkay |
| Posted: Fri Jul 12, 2002 4:48 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Be careful of poisened loops! You are tiggered on first and a message lands, starting your app. You get the message under syncpoint and then roll it back to the queue for whatever reason. As you go to close the queue, the QM realizes that you are closing a triggered on first queue with more than zero messages on it. So it generates another trigger message to the init queue. As soon as your app ends, the trigger monitor sees your app end, sees a trigger message for it on the init queue, and starts it up again. Your app picks up the same message again, rolls it back again, closes the queue again and retriggers itself again, forever and ever!
Any triggered on first apps that get their messages under syncpoint should always check the MQMD-Backoutcount count right after the GET. This is because each time you go thru that above loop, the QM ups the backout count of the message by one. If you see that this # is higher than say, 1, your app knows this message has been picked up at least twice before and may be a problem. Discard it or put it off to an exception queue and get on to the next message on the queue.
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Peter Potkay
Keep Calm and MQ On |
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| Vin |
| Posted: Fri Jul 12, 2002 5:42 pm Post subject: |
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Master
Joined: 25 Mar 2002
Posts: 212
Location: India
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| Appreciate all your suggestions. Questions is, is this possible with JMS? I know that JMS is not really as friendly as MQBase Java? Thanks. |
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| PeterPotkay |
| Posted: Sat Jul 13, 2002 8:49 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| Vin |
| Posted: Sat Jul 13, 2002 1:38 pm Post subject: |
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Master
Joined: 25 Mar 2002
Posts: 212
Location: India
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| Was wondering how to extract this value from the header? could not find any function which will let me do that on the message? any clues? Thanks |
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