Set up objects for triggering

This following sections describe how to set up the required objects to support triggering on WebSphere MQ.

 

Defining an application queue for triggering

An application queue is a local queue that is used by applications for messaging, through the MQI. Triggering requires a number of queue attributes to be defined on the application queue. Triggering itself is enabled by the TRGENBL attribute.

In this example, a trigger event is to be generated when there are 100 messages of priority 5 or higher on the local queue motor.insurance.queue, as follows:

CRTMQMQ MQMNAME(MYQUEUEMANAGER) QNAME('motor.insurance.queue') QTYPE(*LCL)
       PRCNAME('motor.insurance.quote.process') MAXMSGLEN(2000)
       DFTMSGPST(*YES) INITQNAME('motor.ins.init.queue')
       TRGENBL(*YES) TRGTYPE(*DEPTH) TRGDEPTH(100) TRGMSGPTY(5)

where the parameters are:

MQMNAME(MYQUEUEMANAGER)

The name of the queue manager.

QNAME('motor.insurance.queue')

The name of the application queue being defined.

PRCNAME('motor.insurance.quote.process')

The name of the application to be started by a trigger monitor program.

MAXMSGLEN(2000)

The maximum length of messages on the queue.

DFTMSGPST(*YES)

Messages on this queue are persistent by default.

INITQNAME('motor.ins.init.queue')

The name of the initiation queue on which the queue manager is to put the trigger message.

TRGENBL(*YES)

The trigger attribute value.

TRGTYPE(*DEPTH)

A trigger event is generated when the number of messages of the required priority (TRGMSGPTY) reaches the number specified in TRGDEPTH.

TRGDEPTH(100)

The number of messages required to generate a trigger event.

TRGMSGPTY(5)

The priority of messages that are to be counted by the queue manager in deciding whether to generate a trigger event. Only messages with priority 5 or higher are counted.

 

Defining an initiation queue

When a trigger event occurs, the queue manager puts a trigger message on the initiation queue specified in the application queue definition. Initiation queues have no special settings, but we can use the following definition of the local queue motor.ins.init.queue for guidance:

CRTMQMQ MQMNAME(MYQUEUEMANAGER) QNAME('motor.ins.init.queue') QTYPE(*LCL)
       GETENBL(*YES) SHARE(*NO) TRGTYPE(*NONE)
       MAXMSGL(2000)
       MAXDEPTH(1000)

 

Creating a process definition

Use the CRTMQMPRC command to create a process definition. A process definition associates an application queue with the application that is to process messages from the queue. This is done through the PRCDEFN attribute on the application queue motor.insurance.queue. The following command creates the required process, motor.insurance.quote.process, identified in this example:

CRTMQMPRC MQMNAME(MYQUEUEMANAGER) PRCNAME('motor.insurance.quote.process')
          TEXT('Insurance request message processing')
          APPTYPE(*OS400) APPID(MQTEST/TESTPROG)
          USRDATA('open, close, 235')

where the parameters are:

MQMNAME(MYQUEUEMANAGER)

The name of the queue manager.

PRCNAME('motor.insurance.quote.process')

The name of the process definition.

TEXT('Insurance request message processing')

A description of the application program to which this definition relates. This text is displayed when you use the DSPMQMPRC command. This can help you to identify what the process does. If you use spaces in the string, enclose the string in single quotation marks.

APPTYPE(*OS400)

The type of application to be started.

APPID(MQTEST/TESTPROG)

The name of the application executable file, specified as a fully qualified file name.

USRDATA('open, close, 235')

User-defined data, which can be used by the application.

 

Displaying your process definition

Use the DSPMQMPRC command to examine the results of your definition. For example:

MQMNAME(MYQUEUEMANAGER) DSPMQMPRC('motor.insurance.quote.process')

We can also use the CHGMQMPRC command to alter an existing process definition, and the DLTMQMPRC command to delete a process definition.