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| MQ on z/OS sending messages to MQSI |
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| mgrabinski |
 Posted: Thu Feb 27, 2003 12:23 am Post subject: MQ on z/OS sending messages to MQSI |
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Master
Joined: 16 Oct 2001
Posts: 246
Location: Katowice, Poland
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Hi,
I'm experienced with MQ, but novice to MQSI, so my question will be pretty simple.
Here is my scenario: MQ on z/OS should send messages to a hub with MQSI that will route them to various systems.
Question: how does MQSI recognizes messages that should be sent to different locations? Should publish/subscribe be used? If so, is publish/subsrcibe available on z/OS (CICS environment). If not, what are other possibilities for telling messages from each other? MsgID/CorrelID? Some special values in the data part?
Please clarify this to me.
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Marcin Grabinski <>< |
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| zpat |
| Posted: Thu Feb 27, 2003 12:43 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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Routing messages and pub/sub are entirely different things. If you want a single message to be sent to multiple destinations - this is possible with pub/sub.
Pub/sub has advantages when the receiving applications are unknown in advance and may change over time. It's easy to add new subscribers etc - but to be honest apart from the often quoted example of publishing stock prices I have seen very few applications of pub/sub in commercial environments.
More typical is where a MQSI flow decides where to send the messages to based on their content or RFH2 header fields. A destination list can be used or multiple output nodes. The MQSI aggregration nodes are useful in a request/reply situation where "fan out" of requests to backends and "fan in" of responses is needed. This is not pub/sub. |
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| mgrabinski |
| Posted: Thu Feb 27, 2003 4:20 am Post subject: |
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Master
Joined: 16 Oct 2001
Posts: 246
Location: Katowice, Poland
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Thank you for the clarification.
I've got two more questions
1) If there is still a requirment to use pub/sub, is this feature available in CICS on z/OS? As I understand pub/sub is a set of additional API functions. Am I right? What do I need to compile pub/sub programs on a mainframe?
2) You said there are few commercial pub/sub applications. Are there any disadvantages of using it? Performance?
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Marcin Grabinski <>< |
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| zpat |
| Posted: Thu Feb 27, 2003 7:32 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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To be clear - routing messages to multiple destinations does not require pub/sub - that is only one way of implementing it. The reason to do it is for greater application abstraction. The publisher and subscribers can be entirely unaware of each other and can be added/deleted more easily.
Now - pub/sub takes different forms - there is the pure MQSeries queue manager version and there is the MQSI version. There is nothing special about the published messages - you just set the "topic" information in the RFH2 header (I think).
It's not a different API to publish messages - although I think JMS has some special features for it. I don't fully understand how you set a subscription up (although I could read up about it!).
To be honest I've never implemented a pub/sub application. I think the IBM manuals have a reasonable coverage on it. If you have MQSI then you probably will end up deciding it is easier to determine and set the destination list in a MQSI flow. It really depends if you want to exploit the IBM pub/sub features or not. If you don't need those extras, then keep it simple!
I would guess that setting the appropriate routing information in the message or in the RFH2 header and sending it out to MQSI is the best approach. CICS really doesn't need to do anything unusual.
What are the routing criteria? Anything complex may not be possible with pub/sub - it depends on the receiving application's expectations. |
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