The following sections describe some other properties of trigger
messages.
Trigger messages are not persistent as there is no requirement for them to
be so. However, the conditions for generating triggering events
do persist, hence trigger messages will be generated whenever these
conditions are met. In the event that a trigger message is lost, the
continued existence of the application message on the application queue will
guarantee that the queue manager will generate a trigger message as soon as
all the conditions are met.
If a unit of work is rolled-back, any trigger messages it generated will
always be delivered.
Trigger messages take the default priority of the initiation queue.
Following the restart of a queue manager, when an initiation queue is next
opened for input, a trigger message may be put to this initiation queue if an
application queue associated with it has messages on it, and is defined for
triggering.
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 may no longer exist at the time the trigger message is
made available.
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:
- StrucId
- The structure identifier.
- Version
- The version of the structure.
- QName
- The name of the application queue on which the trigger event
occurred. When the queue manager creates a trigger message, it fills
this field using the QName attribute of the application
queue.
- ProcessName
- The name of the process definition object that is associated with the
application queue. When the queue manager creates a trigger message, it
fills this field using the ProcessName attribute of the
application queue.
- TriggerData
- A free-format field for use by the trigger monitor. When the queue
manager creates a trigger message, it fills this field using the
TriggerData attribute of the application queue. On
any of the MQSeries or WebSphere MQ Version 5 products (except WebSphere MQ
for z/OS) or on MQSeries for VSE/ESA, this field can be used to specify the
name of the channel to be triggered.
- ApplType
- The type of the application that the trigger monitor is to start.
When the queue manager creates a trigger message, it fills this field using
the ApplType attribute of the process definition object
identified in ProcessName.
- ApplId
- A character string that identifies the application that the trigger
monitor is to start. When the queue manager creates a trigger message,
it fills this field using the ApplId attribute of the
process definition object identified in
ProcessName. When you use trigger monitor CKTI or CSQQTRMN supplied by WebSphere MQ for
z/OS, the ApplId attribute of the process definition
object is a CICS or IMS transaction identifier.
- EnvData
- A character field containing environment-related data for use by the
trigger monitor. When the queue manager creates a trigger message, it
fills this field using the EnvData attribute of the
process definition object identified in
ProcessName. The WebSphere MQ for z/OS-supplied
trigger monitors (CKTI or CSQQTRMN) do not use this field, but other trigger
monitors may choose to use it.
- UserData
- A character field containing user data for use by the trigger
monitor. When the queue manager creates a trigger message, it fills
this field using the UserData attribute of the process
definition object identified in ProcessName. This
field can be used to specify the name of the channel to be triggered.
There is a full description of the trigger message structure in WebSphere MQ Application Programming Reference.
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