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| WMB best practices - Additional Instances |
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| madi |
 Posted: Thu Mar 26, 2009 6:27 am Post subject: WMB best practices - Additional Instances |
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Chevalier
Joined: 17 Jan 2006
Posts: 475
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Hi All
I have a couple of question on the additional instances for flow.
Q. When we increase the instance count for a flow, do all the threads start right away and are listening to the queue or does broker start new instances based on the work load (depth or Q/outstanding HTTP requests ... etc)
Q. When we process group messages, and have multiple instances picking them up, they will not be processed in order. We don't care if the messages are in order, just that all of them are processed and sent to output queue. But does MQ allow an application which is looking for the whole group start processing messages if they are not in order even if the whole group in on queue??
Thanks
madi
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IBM Certified Solutions Developer - WMB 6.0 |
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| Vitor |
| Posted: Thu Mar 26, 2009 6:41 am Post subject: Re: WMB best practices - Additional Instances |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| madi wrote: |
| Q. When we increase the instance count for a flow, do all the threads start right away and are listening to the queue or does broker start new instances based on the work load (depth or Q/outstanding HTTP requests ... etc) |
As required. Note that the use of MQGet nodes and others can influence how many threads are "required"
| madi wrote: |
| But does MQ allow an application which is looking for the whole group start processing messages if they are not in order even if the whole group in on queue?? |
Your question is odd. If the whole group is on the queue, then the group will be available and the application can start processing. This is the point of grouping.
Please rephrase your question.
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| HOMETOWN47 |
| Posted: Thu Mar 26, 2009 6:52 am Post subject: |
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Apprentice
Joined: 25 Mar 2003
Posts: 34
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See info center help http://127.0.0.1:50076/help/topic/com.ibm.etools.mft.doc/ac09055_.htm?resultof=%22%41%64%64%69% for info on additonal instances of flows.
With regards to MQ message grouping, excerpt from info center page
http://127.0.0.1:50076/help/topic/com.ibm.etools.mft.doc/ac25700_.htm?resultof=%22%67%72%6f%75%70%22%20%22%6d%65%73%73%61%67%65%73%22%20%22%6d%65%73%73%61%67%22%20
If you specify a value of By Queue Order on the Order mode property, the message flow processes the messages in the group in the order that is defined by the queue attributes; this order is guaranteed to be preserved when the messages are processed. This behavior is identical to the behavior that is exhibited if the Additional instances property is set to zero. The message flow processes the messages on a single thread of execution, and a message is processed to completion before the next message is retrieved from the queue. If you do not specify this value, it is possible that multiple threads within a single message flow are processing multiple messages, and the final message in a group, which prompts the commit or roll back action, is not guaranteed to be processed to completion after all other messages in the group.
So setting this value will mean that the message group will be processed by the one message thread.
Hope this helps ! |
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| madi |
| Posted: Thu Mar 26, 2009 7:09 am Post subject: Re: WMB best practices - Additional Instances |
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Chevalier
Joined: 17 Jan 2006
Posts: 475
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| Vitor wrote: |
Your question is odd. If the whole group is on the queue, then the group will be available and the application can start processing. This is the point of grouping.
Please rephrase your question. |
OK. I'll re-phrase.
Input Q
Message1 --> Logical Sequence 1
Message2 --> Logical Sequence 2
Message3 --> Logical Sequence 3
Lets say these message were processed by 2 instances of a flow and sent to an output queue.
Output Q
Message1 --> Logical Sequence 1
Message2 --> Logical Sequence 3
Message3 --> Logical Sequence 2
Will the application picking up from Output Q be able to see that the group is whole??
Hope this is clearer
--madi
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IBM Certified Solutions Developer - WMB 6.0 |
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| Vitor |
| Posted: Thu Mar 26, 2009 7:13 am Post subject: Re: WMB best practices - Additional Instances |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| madi wrote: |
| Will the application picking up from Output Q be able to see that the group is whole?? |
Yes, because the group won't be presented to the application until the putting application has signalled that the group is complete.
This is all very clearly laid out in the documentation. 
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