WebSphere MQ Triggering Q&A

What is Triggering?
Ans: Web Sphere MQ enables you to start an application automatically when certain conditions on a queue are met. For example, you might want to start an application when the number of messages on a queue reaches a specified number. This facility is called triggering

How many ways of Triggering?
EVERY: A trigger event occurs every time that a message arrives on the application queue. Use this type of trigger if you want a serving program to process only one message, then end.

FIRST: A trigger event occurs only when the number of messages on the application queue changes from zero to one. Use this type of trigger if you want a serving program to start when the first message arrives on a queue, continue until there are no more messages to process, then end.

DEPTH: A trigger event occurs only when the number of messages on the application queue reaches the value of the TriggerDepth attribute.

What are the Trigger types available Explain?
a. Application triggering

b. Channel Triggering

a)     In the case of application triggering the components are Application queue: This is the message queue associated with an application Process: A process definition defines the application to be used to process messages from the application queue. Initiation queue: The queue manager moitors the application queue. If the trigger type of the application queue is set to Every then whenever a message is put to the application queue, the q manager looks into the process definition and puts a message having the application name and other details to the initiation queue Trigger monitor: The trigger monitor gets the trigger message from the initiation queue and starts the program specified.

b) For channel triggering the transmission queue is monitored and when messages are put in the transmission queue, the q manager puts a message in the channel initiation queue. The channel initiator is the program which monitors the initiation queue and starts the sender MCA. For the message to reach the target queue, the channel listener has to be running in the target queue manager

Channel Triggering Conditions:

· Trigger ON
· Trigger type(first every depth)
· Trigger data(channel name which is to be fired)
· Initiation queue(SYSTEM.CHANNEL.INITQ)

Channel Triggering Background process:

1. The local queue manager places a message from an application or from a message channel agent (MCA) on the transmission queue.

2. When the triggering conditions are fulfilled, the local queue manager places a trigger message on the initiation queue.

3. The long-running channel initiator program monitors the initiation queue, and retrieves messages as they appear.

4. The channel initiator processes the trigger messages according to information contained in them. This information may include the channel name, in which case the corresponding MCA is started.

5. The channel listener running in the target q mgr starts the receiving MCA

Application Triggering Conditions:

- Trigger ON
- Trigger type (first every depth)
- Initiation queue (SYSTEM.DEFAULT.INITIATION.QUEUE our own defined local queue)
- Process (NOTEPAD)

DEFINE QLOCAL (LQ) TRIGGER TRIGTYPE (EVERY) INITQ (IQ) PROCESS (NOTEPAD).
DEFINE PROCESS (NOTEPAD) APPLICID (NOTEPAD.EXE) APPLTYPE (WINDOWS)
Runmqtrm –m QM1 –q IQ

Channel Triggering Conditions:

· Trigger ON
· Trigger type(first every depth)
· Trigger data(channel name which is to be fired)
· Initiation queue(SYSTEM.CHANNEL.INITQ)

BACKGROUND PROCESS:

1.      When ever the message comes to triggered local queue, queue manager will fire trigger message with information called trigger type and the process definition (application which is to be triggered) in to the initiation queue (IQ) (our own queue).

2.      At the initiation queue a long running time program called trigger monitor will be watching (monitoring) the initiation queue.

3.      Whenever the trigger message occurs in the initiation the trigger monitor will pick the information and starts the application which is defined in the process.

What is a Trigger monitor?
Trigger monitor is a continuously - running program that serves one or more initiation queues. When a trigger message arrives on an initiation queue, the trigger monitor retrieves the message. The trigger monitor uses the information in the trigger message. It issues a command to start the corresponding application/channel

What is the command used for the running trigger monitor?
Ans: On Server side: runmqtrm -m QMName -q Initiation QueueName

On Client side: runmqtmc -m QMName -q Initiation QueueName