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MQSeries.net Forum Index » IBM MQ API Support » How does MQSeries server maintains subscriptions for diff su

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bilal
PostPosted: Mon Feb 04, 2002 5:54 pm    Post subject: Reply with quote

Newbie

Joined: 31 Jan 2002
Posts: 5
Location: San Fran

Hi,
I have a dll that open queue, subscribe to topic and wait for messages to arrive and everything works fine.
Now I a scenario in which there will be more than one processes who will use this same dll.

Application_1 (which uses MY_DLL)
- Open SYSTEM.JMS.ND.SUBSCRIBER.QUEUE
- Subscribes to TOPIC_1
- Waits for messages

Application_2(uses MY_DLL)
- Open SYSTEM.JMS.ND.SUBSCRIBER.QUEUE
- Subscribe to TOPIC_2
- Waits for messages.

Both Application_1 & Application_2 are receiveing messages on both topics i.e.
TOPIC_1 & TOPIC_2. When I intended Application_1 to receive msgs on TOPIC_1
and Application_2 on TOPIC_2.

I think the application have some kind of Identification issues.

Questions
- Do I have to specify some kind of Application identification ?
- How does MQSeries makes this link b/w subscriber & publisher ?

regards
bilal
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kolban
PostPosted: Mon Feb 04, 2002 6:36 pm    Post subject: Reply with quote

Grand Master

Joined: 22 May 2001
Posts: 1072
Location: Fort Worth, TX, USA

I smell big confusion here ... if you are writing a DLL, I am assuming that you are not using Java. If you are not using Java then you can't be using JMS ... if you are not using JMS, then the SYSTEM.JMS.ND.SUBSCRIBER.QUEUE does not play any part in the story ... worse, even if you were using Java, the queue is used internally by MQSeries and your applications should never open the queue.

I think what you really want is to read about the MA0C Pub/Sub broker. This is a demon that tracks the relationship between subscribers and consumers and utilizes the RFH1 header as the " control language" for registering subscriptions and publishing information. The manual for this can be found at http://www-4.ibm.com/software/ts/mqseries/txppacs/ma0c.html
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bilal
PostPosted: Tue Feb 05, 2002 5:21 pm    Post subject: Reply with quote

Newbie

Joined: 31 Jan 2002
Posts: 5
Location: San Fran

Hi Kolban,
- Yes i am using MQI on Windows2000
Here is the scenario

Publisher -- JMS
Subcriber --- MQI application.

I looked at the manual you mentioned.
In the command to register as a subscriber to TOPIC_1 I also specified MY_QUEUE
instead of SYSTEM.JMS.ND.SUBSCRIBER.QUEUE and it seems to be working fine.

am I right in assuming that whenever a subscriber subscribes to a topic it also has to specify the queue where it wants all its subscriptions delivered.

Does each subscribe has to has its own SubQ ?

You have been a GREAT help
Best Regards
Shuaib.

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kolban
PostPosted: Tue Feb 05, 2002 9:38 pm    Post subject: Reply with quote

Grand Master

Joined: 22 May 2001
Posts: 1072
Location: Fort Worth, TX, USA

Simply put .. yes and yes.

The MA0C PubSub broker on which JMS is based associates a "topic" with a named queue. So when a subscriber registers a subscription, what it is actually saying is:

"Hey broker, when someone publishes a message with topic xyz, please put a copy of that message on my queue queueXYZ"

By default, a JMS subscriber (non-durable), dynamically creates a queue and the topic is associated with that dynamic queue. When the subscriber goes away, the dynamic queue goes away and the subscription is broken.

For a durable subscriber, I believe that, by default, all durable subscriptions are routed to the same queue and an intra-queue selection mechanism is employed (e.g. MsgId or CorrelId).
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