IMS message switches

IMS treats a message switch that is sent or received just like a recoverable transaction.

For this reason, the following applies to message switches:
  • A message switch must request a DR1 or DR2 if the workstation is defined with the ACK option. If the OPTACK option is specified, a message switch optionally requests an exception DR1 or DR2 and should specify begin-bracket and change-direction on input to IMS.
  • A message switch is recovered by IMS.
  • The sequence number of a message switch is used in message resynchronization.