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| vignesh2015 |
 Posted: Mon Dec 21, 2015 9:58 am Post subject: MQ Message Delivery Sequence Question |
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Newbie
Joined: 21 Dec 2015
Posts: 2
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Hello All,
We have an local queue on Unix queue manager running in MQ V7.1
That local queue has "Default Sequence" Priority
The application team is asking "How can they change there application configuration to make the messages process through FIFO without changing the Physical Queue Attribute"
Can someone help me in this query.
Thanks
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| Vitor |
| Posted: Mon Dec 21, 2015 10:50 am Post subject: Re: MQ Message Delivery Sequence Question |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| vignesh2015 wrote: |
| The application team is asking "How can they change there application configuration to make the messages process through FIFO without changing the Physical Queue Attribute" |
Send all their messages with the same priority. 
Note that this simply increases the chances of messages arriving in the same sequence as they were put, it doesn't absolutely guarantee it.
Needing messages to arrive on a queue in a given sequence is commonly because of "message affinity", where the processing of the second message in the queue is dependent on the first message in the queue, and the processing of the third messages on the second, and so on with the nth message relying on the n-1th message being processed.
This is a very bad design pattern for a number of reasons. Confirm with your application team they're not doing that.
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| vignesh2015 |
| Posted: Mon Dec 21, 2015 10:57 pm Post subject: |
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Newbie
Joined: 21 Dec 2015
Posts: 2
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Thanks
So, do you say that it's always better to change the queue attribute rather asking the sender to send the messages with equal priority?
Please advise
Thanks
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| fjb_saper |
| Posted: Tue Dec 22, 2015 12:03 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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No what he is saying is laid out in the documentation:
| Quote: |
| You cannot guarantee the order of the messages in a queue if there are multiple paths to deliver the messages to the queue |
Think as well of problems that may send some messages to the DLQ and disrupt queue order (queue full) etc... 
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| Vitor |
| Posted: Tue Dec 22, 2015 5:25 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| vignesh2015 wrote: |
| So, do you say that it's always better to change the queue attribute rather asking the sender to send the messages with equal priority? |
No, what I'm saying is that any application that is trying to ensure messages are processed in the exact order that they're sent is using a very poor design.
My worthy associate has provided a useful quote, and a couple of instances when this design will fall flat on it's face. I'll also point out that it's almost impossible to scale such a design.
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| mqjeff |
| Posted: Tue Dec 22, 2015 7:24 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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You can process messages in order without needing them to arrive on a queue in order.
This requires that your application is actually written to meet the business requirement.
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| bruce2359 |
| Posted: Tue Dec 22, 2015 9:58 am Post subject: Re: MQ Message Delivery Sequence Question |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| vignesh2015 wrote: |
Hello All,
We have an local queue on Unix queue manager running in MQ V7.1
That local queue has "Default Sequence" Priority
The application team is asking "How can they change there application configuration to make the messages process through FIFO without changing the Physical Queue Attribute"
Can someone help me in this query.
Thanks
|
Message Delivery Sequence only dictates how messages are delivered out of a queue to a consuming application - FIFO (first-in, first-out) or by Priority.
Is the intent of your post that some messages will be delivered to a consuming application FIFO and other messages will be delivered by Priority - out of the same queue? By (to) the same or different consuming apps?
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