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| fail over queue ? |
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| anbures |
 Posted: Wed Nov 12, 2003 8:48 am Post subject: fail over queue ? |
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Newbie
Joined: 12 Nov 2003
Posts: 6
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hi all,
I have a general doubt.
The scenario is like this and correct me if my understanding is wrong.
Assume that in production, 30000 messages are continuously coming from remote queue manager via transmission queue. My understanding is, here (in the remote QM at host 'HostA' ) mca won't know the base queue name and resolve only the remote queue manager name and starts sending the message to the destination mca at host 'HostB'.
The destination MCA (HostB mca) will get the message one by one and looks for a base queue name when opening alias queue to put the messages.
If my assumption is correct  , the first 24999 messages will go to the base queue (say 'B1.queue') and then it just started to send the 25000th message to the base queue (B1.queue) which is already resolved by MQOPEN.
My Question is if suddenly the base queue name is changed to a new base queue(B2.queue) in the alias queue,
1)where will the remaining 5000 messages to be sent from HostA(MCA) to HostB(MCA) will go? (to old base queue B1.queue or new base queue B2.queue?)
2)what will happen to the 25000 th message which is partially transferred to B1.queue before the attribute change event occurs.?
3) Generally will the MCA opens the queue for each and every messages when it arrives through channel or will it keep many queue handles for a period of time to put messages in different queues.?
I am really sorry if I have not explained you properly
Thanks in advance. 
Anbu. |
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| mpuetz |
| Posted: Wed Nov 12, 2003 2:01 pm Post subject: |
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Centurion
Joined: 05 Jul 2001
Posts: 149
Location: IBM/Central WebSphere Services
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Hi,
if you modify an alias queue which is the targq for a remote queue
on another qmgr, you can't do so while the object is in use (unless you FORCE it).
If your receiver channel still has the queue open, you can't change it. If you FORCE the alias change, the MQ channel agent will detect the object changed error and reopen the queue for output.
Most (other) applications (a channel agent is an MQ application) do
not detect the special object changed error and will fail.
1) Your 5000 remaining messages should go to the new queue
2) It should go to the new queue, since its put to the old one fails,
but the channel agent handles that gracefully
3) The channel agent will keep any output queue it opened open in
expectation of new messages going to the same destination. It will
close them only when the channel goes inactive (or an error like the
above occurs and it reopens its queues)
_________________
Mathias Puetz
IBM/Central WebSphere Services
WebSphere Business Integration Specialist |
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