MSC and OTMA transactions
You can use IMS Multiple Systems Coupling (MSC) with OTMA transactions.
MSC processing in an OTMA environment is similar to MSC processing in an APPC/IMS environment:
- A client sends a transaction to IMS. If the transaction is defined as remote for that IMS system, it is sent to a remote IMS system for processing. If the transaction is defined as a local transaction and performs a message switch to another IMS system, the switched message is sent to that remote IMS system for processing.
- Output from the remote application program is returned to the originating IMS.
- IMS recognizes that the data is OTMA data and uses the transaction pipe to send the data to the client.
If the remote application inserts to an alternate PCB that is a remote destination, the data is not routed to an OTMA destination. The remote destination does not route the output message to the OTMA client, even though the message has a prefix. If the message is to be properly routed back to the original client, the remote IMS must insert to a remote transaction. That transaction (at the original IMS site) must then send the message to the OTMA client using an alternate PCB and a Prerouting exit routine.
You can use MSC with OTMA in a shared-queues environment, as long as the MSC link exists in the front-end IMS subsystem that is connected to the OTMA client.