IMS Connect message structures

TCP/IP clients using the z/OS® program call interface communicate with IMS Connect by using an IMS request message (IRM) header on each input message. The IRM header is used on input messages from IMS Connect client application programs to communicate protocol options to IMS Connect. The IRM header is mapped by the IMS Connect HWSIMSCB macro.

IMS Connect communicates with OTMA through an z/OS cross-system coupling facility session using the OTMA message headers. One of the primary tasks of the client-specific IMS Connect user-message exit routines is to translate the IRM header into the OTMA header on input.

Clients that use TCP/IP socket calls as their communication vehicle can design a user message exit routine that runs with IMS Connect to convert messages between formats as follows:
  • Convert the client message format to OTMA message format.
  • Convert the IMS response, in OTMA message format, to client message format.
  • Convert XML in the user data portion of messages to COBOL and back again.

These conversions enable the client to retrieve IMS data through a TCP/IP connection. IMS Connect automatically sends and receives messages when they are formatted correctly.

Depending on the type of IMS Connect client and the user message exit used to support the client, the format of the IRM message header differs.

The following user message exit routines require specific message formats:
  • HWSSMPL0 and HWSSMPL1
  • HWSJAVA0
  • HWSCSLO0 and HWSCSLO1
  • HWSSOAP1