CODEWITHSUNDEEP
javajmsibm-mqmessage-queue
diziaq
diziaq

Reputation: 7785

What is the purpose of setting QueueManager property for IBM MQ?

Following this example of sending messages to queue let's look at the part of setting connection factory properties

        cf.setStringProperty(WMQConstants.WMQ_HOST_NAME, HOST);
        cf.setIntProperty(WMQConstants.WMQ_PORT, PORT);
        cf.setStringProperty(WMQConstants.WMQ_CHANNEL, CHANNEL);
        cf.setIntProperty(WMQConstants.WMQ_CONNECTION_MODE, WMQConstants.WMQ_CM_CLIENT);
        cf.setStringProperty(WMQConstants.WMQ_QUEUE_MANAGER, QMGR);
        cf.setStringProperty(WMQConstants.WMQ_APPLICATIONNAME, "JmsPutGet (JMS)");
        cf.setBooleanProperty(WMQConstants.USER_AUTHENTICATION_MQCSP, true);
        cf.setStringProperty(WMQConstants.USERID, APP_USER);
        cf.setStringProperty(WMQConstants.PASSWORD, APP_PASSWORD);

When the line cf.setStringProperty(WMQConstants.WMQ_QUEUE_MANAGER, QMGR); is removed then nothing changes: the client still can successfully send and receive messages.

What is the purpose of setting WMQConstants.WMQ_QUEUE_MANAGER property here?

IBM MQ server is a container based on this Dockefile:

FROM ibmcom/mq:9.2.2.0-r1

ENV LICENSE=accept
ENV MQ_DEV=true
ENV MQ_APP_PASSWORD=app-password
ENV MQ_ADMIN_PASSWORD=admin-pwd
ENV MQ_QMGR_NAME=KUPOL_DEV_QM

Additionally:
In the same example we see the line
destination = context.createQueue("queue:///" + QUEUE_NAME)
and it does not break the app if the prefix "queue:///" is removed, leaving the line as
destination = context.createQueue(QUEUE_NAME).

And I see similar things in multiple examples for IBM MQ across the web.
What is going on with this code? Is it blind copy-pasting or is there an intention?

Upvotes: 0

Views: 990

Answers (2)

Matt Pavlovich
Matt Pavlovich

Reputation: 4306

Your sample code appears to be JMS. IBM MQ supports a couple of addressing models for queues.

All three of these mean the same thing:

  1. context.createQueue("MY.QUEUE");
  2. context.createQueue("queue://MY.QUEUE");
  3. context.createQueue("queue:///MY.QUEUE");

However, with the triple-slash you can also fully-qualify REMOTE queues

  1. context.createQueue("queue://QMGRB/MY.OTHER.QUEUE");

This tells IBM MQ to send the message to the QMgr and have it deliver the message to the Remote Queue 'MY.OTHER.QUEUE' on 'QMGRB'.

Note: IBM MQ also supports destination options, so you can modify persistence, priority, character encoding, targetClient, etc. This is useful so you can externalize the configuration and change the message pattern without having to change the code!

ref: https://www.ibm.com/docs/en/ibm-mq/9.0?topic=applications-creating-destinations-in-jms-application

Upvotes: 2

JoshMc
JoshMc

Reputation: 10642

If you leave queue manager unset or specify a value that is prefixed with a * you can connect to any queue manager name listening on the host and port you specify.

If you specify a queue manager name that is not prefixed with a * then it must match the name of the queue manager listening on the host and port.

You can also use a CCDT to hold the the connection details, in this case (in addition to the above points) the queue manager name you specify is used to look up the connection details in the CCDT. If it is prefixed with a * it will look up the name without the * in the CCDT.

In addition to specifying queue names with the queue:/// prefix, you can also specify topics with the prefix topic:///, my guess is createQueue defaults to assume you are specifying a queue name.

Upvotes: 4

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