OTMA support for callout requests

IMS application programs running in IMS dependent regions can call out through the Open Transaction Manager Access (OTMA) component of IMS to servers that are outside of the IMS installation to request data or services. The synchronous callout interface can also be used to request services from another IMS application with a synchronous program switch.

An IMS configuration that supports for such callout requests requires multiple components. The components that are required differ depending on whether the callout requests are processed synchronously or asynchronously.

OTMA is not required for synchronous program switch requests. Synchronous program switch requests are queued as OTMA transactions, but IMS transparently routes the requests to the specified transactions with an internal implementation of the OTMA send-then-commit (CM1) protocol. You do not need to start an XCF connection with an OTMA client, specify OTMA=Y in the DFSPBxxx member of the IMS.PROCLIB data set, or issue a START OTMA command.