Assumptions for OTMA resynchronization

The OTMA resynchronization process is based on several assumptions.

The assumptions include:
  • Neither client nor IMS sends an ACK message until it has logged a transaction message.
  • The client decides what resynchronization actions IMS should take.
  • Both client and IMS can determine whether a transaction and its output messages are recoverable. The client can determine a transaction's recoverability using the architected form of the /DISPLAY TRANSACTION command.
  • Recoverable OTMA messages include a value for the recoverable sequence number in the message-control information section of the message prefix. This value is incremented by 1 every time a recoverable message is sent using a tpipe (see Summary results of IMS transactions and commands).
  • A 0 (zero) is not a valid recoverable sequence number.
  • Recoverable send- and receive-sequence numbers are maintained on a per transaction pipe basis.
  • IMS does not support resynchronization for any IMS command input. If the client needs to submit IMS commands using a synchronized transaction pipe, the recoverable sequence number must be set to 0 (zero). If the recoverable sequence number is not set to 0 (zero), IMS rejects the command input with sense code X'0023'.