Session failures because of IMS failure

A session failure that also involves an IMS subsystem failure might occur before IMS responds to a synchronization request on response mode (if the message was recoverable) or conversational mode input.

When the session is reestablished, the DFC state set by IMS by the bind indicates IMS as bound in-brackets/SEND. In either case, because of the IMS restart process from the subsystem log, the subsequent STSN sequence number recovery reflects that the input message has been committed even if that commit has not yet actually occurred. However, this condition produces inconsistent results only if the transaction subsequently abnormally terminates after being restarted. In this case, the response mode output reply message is made available for asynchronous (ATTACH EB or ATTACH ATTDPN=SCHEDULER) delivery on the recovered ISC session.