Output message to client

The output message from IMS is passed to the user message exit routine that was called from the client.

The user exit normally removes the OTMA headers for output if the exit added the OTMA headers for input. The user exit normally translates the data from EBCDIC to ASCII if it did the translation for input. And the reverse is true if these things were not done for input.

The OTMA header can consist of up to four sections and application data. If the exit is to remove the OTMA header (not present on input), there must be a check for each section. The four sections include:
  • Control (always present in the OTMA structure)
  • Header (might or might not exist in the OTMA structure)
  • Security (might or might not exist in the OTMA structure)
  • User (might or might not exist in the OTMA structure)

Output message from IMS-to-IMS Connect

All output messages received by IMS Connect from IMS consist of the same structure, the OTMA header followed by LLZZ DATA. If the message contains multiple segments, then the OTMA header and LLZZ DATA are repeated for the number of segments in the message.

For CM0 multi-segment output messages, if the IMS application program issues a DL/I PURG call after it inserts each segment to the TP PCB, each segment of the output message is sent to the IMS Connect client separately.

If your IMS application issues a PURG call for each segment of multi-segment CM0 output messages, you can instruct OTMA to ignore PURG calls until the last segment of the message is inserted to the TP PCB by specifying X'02' (OMHDRIPG) in the OMHDRCFL field of the state data section of the OTMA message header. When OMHDRIPG is specified, OTMA returns the output message to IMS Connect as a single multi-segment message.

User-written IMS Connect clients can set the OMHDRIPG flag by specifying X'20' (IRM_F3_IPURG) in the IRM_F3 field of the user portion of the IRM prefix of input transaction messages.

If an input message to IMS contains distributed network security credentials in the security-data section of the OTMA message prefix, output messages to IMS Connect clients that issued a RESUME TPIPE call can also contain the network security credentials. You can enable network security credentials to be included in output messages by specifying X'80' in the IRM_F6 field of the user portion of the IRM prefix of input transaction messages. If X'80' is not specified in the IRM_F6 field, IMS removes the network security credentials from the security section of the OTMA header in the output message, even if the security credentials are included in the input message.

Output message from IMS returned by the exit back to IMS Connect

The message returned to IMS Connect from the exit consists of one of two structures:

  • Messages with OTMA structures imbedded in the message
  • Message with no OTMA structures imbedded in the message