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| What are poison messages |
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| wbimb |
 Posted: Thu Aug 24, 2006 10:59 pm Post subject: What are poison messages |
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Centurion
Joined: 17 Aug 2006
Posts: 144
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My understanding about poison messages
A message is send across and it the same message comes back and lands in the local Q..when more messages are put in the local q they are not processed becuase of this message...then the messages tht came back is poison messages
I dont know whether i am right..
HOW DO I TEST for poison messages |
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| Vitor |
| Posted: Fri Aug 25, 2006 12:39 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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Essentially correct. A poision message is one that fails to be procesed by the reading application (data error, logic error, etc) and as a result is rolled back onto the queue. All other things being equal it will be the next message read off the queue, it fails again, is rolled back and thus the cycle continues with the newer messages piled up behind it.
The reading application should check BackoutCount on the MQMD when the message is read. If it's not zero then the message has been read off that many times before and it's a potentially poisoned message. Potentially because the previous error could have been caused by a transatory problem, like database locked, and processing may succeed this time. It's an application decision how many times a message will be retried.
There's an option on the queue called BackoutThreshold which you can use to hold the number of times the application should retry. Likewise there's BackoutQueue which can hold the queue name to dump the message into. Saves hard coding these values.
Note - despite these values being on the queue they are a convienience. The queue manager will not use them for anything, this process cannot be automated within MQ.
Well, not in this version. Maybe in v7......... 
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Honesty is the best policy.
Insanity is the best defence. |
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| bower5932 |
| Posted: Fri Aug 25, 2006 3:18 am Post subject: |
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Jedi Knight
Joined: 27 Aug 2001
Posts: 3023
Location: Dallas, TX, USA
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| wbimb |
| Posted: Fri Aug 25, 2006 4:05 am Post subject: |
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Centurion
Joined: 17 Aug 2006
Posts: 144
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