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Properties of trigger messages

The following topics describe some other properties of trigger messages.


Persistence and priority of trigger messages

Trigger messages are not persistent because there is no requirement for them to be so.

However, the conditions for generating triggering events do persist, so trigger messages are generated whenever these conditions are met. If a trigger message is lost, the continued existence of the application message on the application queue guarantees that the queue manager generates a trigger message as soon as all the conditions are met.

If a unit of work is rolled back, any trigger messages it generated are always delivered.

Trigger messages take the default priority of the initiation queue.


Queue manager restart and trigger messages

Following the restart of a queue manager, when an initiation queue is next opened for input, a trigger message can be put to this initiation queue if an application queue associated with it has messages on it, and is defined for triggering.


Trigger messages and changes to object attributes

Trigger messages are created according to the values of the trigger attributes in force at the time of the trigger event.

If the trigger message is not made available to a trigger monitor until later (because the message that caused it to be generated was put within a unit of work), any changes to the trigger attributes in the meantime have no effect on the trigger message. In particular, disabling triggering does not prevent a trigger message being made available once it has been created. Also, the application queue might no longer exist at the time that the trigger message is made available.


Format of trigger messages

The format of a trigger message is defined by the MQTM structure.

This has the following fields, which the queue manager fills when it creates the trigger message, using information in the object definitions of the application queue and of the process associated with that queue:

There is a full description of the trigger message structure in MQTM.