Why can't I use multiple transmission queues in my WebSphere MQ cluster?
Marcela Adan 100000THF9 firstname.lastname@example.org | | Tags:  messaging mq cluster ross websphere alex queue middleware transmission
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By Alex Ross
IBM WebSphere MQ Software Engineer
IBM Hursley Laboratory
As a tester in the WebSphere MQ development team I get to hear a lot about the new features that are coming in the next release so that I can plan how I to go about testing them. When I heard about multiple cluster transmission queues I thought “it sounds amazing. Exactly what our customers were asking for!”.
This new feature in WebSphere MQ V7.5 improves application isolation, and makes it easier to monitor the traffic being sent to different clustered destinations. A queue manager can automatically create multiple transmission queues. Instead of all clustered traffic sharing the same SYSTEM.CLUSTER.TRANSMIT.QUEUE, independent queues can be used.
Hearing that it was going to be implemented in two different ways, let me plan my tests in advance of the development work being completed.
The first and quickest way to enable multiple transmission queues is to alter a queue manager attribute called DEFCLXQ. When this attribute is set to CHANNEL, the next time the cluster sender channels start, they each have their own automatically created transmission queue. Simple!
It's also possible to manually define a transmission queue and link it to a channel by altering its CLCHNAME attribute.
Now customers can monitor traffic to different queue managers or for different applications in their cluster with much great ease. Application traffic can be split over different transmission queues and if one destination became unavailable the transmission queue won't build up a big back log of messages.
I've given presentations on the new enhancements to clustering and even a workshop. General feedback has been very positive and I can't wait to hear about more customers using it in the field. If you really want to learn more about it, I am one of the authors of an IBM Redbooks publication IBM WebSphere MQ V7.1 and V7.5 Features and Enhancements in which I have gone into greater detail on how to use the new attributes and demonstrated a working scenario.
The scenario uses Windows and Linux to demonstrate how to start using multiple cluster transmission queues. I included a z/OS queue manager as a destination to show that, even though z/OS does not have this enhancement, it doesn't affect the behavior from the distributed platforms end.
You can download the book IBM WebSphere MQ V7.1 and V7.5 Features and Enhancements at http://www.redbooks.ibm.com/abstracts/sg248087.html
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