Posted: Mon Mar 19, 2007 3:33 am Post subject: Shared queues and CICS and clustering
Voyager
Joined: 27 Sep 2005 Posts: 99 Location: Croatia
I intend to implement queue sharing in development environment. I have got two z/OS LPARs which are in Sysplex and two Websphere MQ V6.0 queue managers on it. I will define shared queues which messages will reside in CF structures. The application and initiation queue will be shared. The messages will come to the shared application queue and trigger the CICS proccess. My question is how to control the workload? I know that if one CICS fails the messages will be proccessed in an other CICS region. Is there the Round Robin alogorithm? In other words, after every UOW on the first CICS and queue manager, the next UOW will be proccessed on an other CICS region and queue manager!?
Is it possible to define the shared queue in queue sharing group also as the cluster queue because I need to send messages from the Windows server? Clustering really works fine and in that way I will reduce the amount of the definitions on the Windows server. Thanks for help in advance!
Whichever CICS region/transaction gets to the message first will process the message. It is basically a race between the CICS regions. If one is busy you may see more of the messages processing in the less busy region. There is no round robin like you are familiar with in clustering. You will see the comment 'pull workload balancing' mentioned in the manuals when discussing shared queues. You should have a read of this.
You should have a read on triggering in a QSG as there are subtle differences in how triggering works depending on whether you use trigger every or trigger first and use a shared initq or a non-shared initq.
You may also notice CICS transactions triggering but not processing any message (you may see transactions getting more 2033 errors). Do not be alarmed. All this means is the message was processed in the other region.
I understand you this is the race race between CICS regions to procces the messages. Did you try to trigger batch jobs on the shared qeues? I supose they work in the same way as CICS transactions!
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