Watching for messages

The system provides a watch-for-event function that allows you to watch for messages.

The watch-for-event function allows you to specify messages for which you want the system to watch. When these messages occur, a user exit program is called to take any necessary action. You must specify the message queue or job log where you expect the message to be sent. You can specify some text string to be compared against the message data, the from-program, or the to-program. You can also select watches by message type or severity. Using this watch selection capability allows you to be informed of only certain messages.

Note: Be careful when starting message watches. Do not create never-ending loops of watch notifications. For example, do not start a message watch in *ALL jobs for the job-start message CPF1124.

Use the Start Watch (STRWCH) command to start a watch session and be notified when a specified message occurs. When the watched-for message is added to the specified message queue or log, the watch exit program is called. The watch exit program runs in a job in the QUSRWRK subsystem.

The Work with Watches (WRKWCH) command can be used to show a panel with the list of active watches on the system. The End Watch (ENDWCH) command can be used to end watch sessions.

The Start Watch (QSCSWCH) and End Watch (QSCEWCH) APIs have a similar usage to the STRWCH and ENDWCH commands.

The Retrieve Watch Information (QSCRWCHI) and Retrieve Watch List (QSCRWCHL) APIs can be used to obtain information about watches.

The watch for event function is also incorporated into some trace commands:

Start Trace (STRTRC)
Start Communications Trace (STRCMNTRC)
Trace Internal (TRCINT)
Trace Connection (TRCCNN)
Trace TCP Application (TRCTCPAPP)

Watch support enhances the trace functions by automatically monitoring and ending traces when certain predetermined criteria are met. Using watch support can prevent the loss of valuable trace data and reduce the amount of time you need to spend monitoring traces.