Trigger Message Flows in CICS
When SXCOTRED receives control, it does a series of steps.
- Gets parameters from either CommArea or Container.
- Analyses parameters for validity.
- Checks for active RED interface in CICS.
- Gets access to the user data based on input passed.
- Two methods of SSES selection are available; Primary/Alternative and Round-Robin.
- Sends the RED message to Substation ES using
Send,
Send with Confirm, or
Send with Reply indicating the RED Service to use.
- All Substation ES (could be one or many on same or different LPARs) monitoring SXCOTRED requests validate Service availability.
- SXCOTRED transfers the message to Substation ES.
- SXCOTRED waits for response (if required) with a timeout.
- Substation ES handles the message and forward it to its destination, and then gets reply and returns it to the waiting SXCOTRED program.
- SXCOTRED returns the results of the call in the parameter control block and response message as indicated.
The following figure shows the trigger message transfer in CICS:
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