The WebSphere MQ message queue

A WebSphere MQ message queue, QMQMMSG, is created in each queue manager library. Operating system messages are sent to this queue when queue manager jobs end and WebSphere MQ sends messages to the queue. For example, to report which journal receivers are needed at startup. Keep the number of messages in this message queue at a manageable size to make it easier to monitor.

 

Default system examples

The following examples show how an unmodified WebSphere MQ installation works when some of the standard jobs are submitted at queue manager startup time.

The first job that is started is the execution controller, AMQZXMA0.

  1. Issue the STRMQM command for queue manager TESTQM.

  2. WebSphere MQ searches the queue manager library QMTESTQM, firstly for job description AMQZXMA0, and then job description QMQMJOBD.

    Neither of these job descriptions exist, so WebSphere MQ looks for job description AMQZXMA0 in the product library QMQM. This job description exists, so it is used to submit the job.

  3. The job description uses the WebSphere MQ default job queue, so the job is submitted to job queue QMQM/QMQM.

  4. The routing data on the AMQZXMA0 job description is QMQMRUN20, so the system searches the subsystem routing entries for one that matches that data.

    By default, the routing entry with sequence number 9900 has comparison data that matches QMQMRUN20, so the job is started with the class defined on that routing entry, which is also called QMQMRUN20.

  5. The QMQM/QMQMRUN20 class has run priority set to 20, so the AMQZXMA0 job runs in subsystem QMQM with the same priority as most interactive jobs on the system.

The next job that starts is the checkpoint process, AMQALMPX.

  1. WebSphere MQ searches the queue manager library QMTESTQM, firstly for job description AMQALPMX, and then job description QMQMJOBD.

    Neither of these job descriptions exist, so WebSphere MQ looks for job descriptions AMQALMPX and QMQMJOBD in the product library QMQM.

    Job description AMQALMPX does not exist but QMQMJOBD does, so QMQMJOBD is used to submit the job.

    Note:
    The QMQMJOBD job description is always used for WebSphere MQ jobs that do not have their own job description.

  2. The job description uses the WebSphere MQ default job queue, so the job is submitted to job queue QMQM/QMQM.

  3. The routing data on the QMQMJOBD job description is QMQMRUN35, so the system searches the subsystem routing entries for one that matches that data.

    By default, the routing entry with sequence number 9910 has comparison data that matches QMQMRUN35, so the job is started with the class defined on that routing entry, which is also called QMQMRUN35.

  4. The QMQM/QMQMRUN35 class has run priority set to 35, so the AMQALMPX job runs in subsystem QMQM with a lower priority than most interactive jobs on the system, but higher priority than most batch jobs.