Transaction processing point of failure

The point of failure in the processing of a transaction also affects its recoverability.

For example, when a local or remote transaction processes and reaches a commit point (sync point), IMS recovers the output response (from the log) even if you have defined the transaction as irrecoverable. Local APPC discardable transactions reach a commit point after IMS sends the output response message to the inputting APPC application program. In this situation, IMS has no output response message to recover or discard if a failure occurs after the commit point. If IMS has queued the transaction on an MSC link, IMS recovers the transaction across link failures.

A message can be either recoverable or irrecoverable, and either discardable or nondiscardable, according to the type of failure that might occur. The descriptions in this topic show you what happens to your transaction when the LU 6.2 session, MSC link, local IMS, intermediate IMS, remote IMS, or application program fail. This information assumes that you can recognize where a failure has occurred and what you need to do to recover.