# Installing OTMA Message Routing

If you want to have messages routed through OTMA to Substation ES IMS Interface, you have to first set up the OTMA messaging routing. IMS transactions that did not originate through OTMA can route messages through OTMA to Substation ES.

In Substation ES, messages originating from host-side applications are known as trigger messages or triggers. The destination to which the IMS applications routes messages is called the trigger destination name. The default trigger destination name for the IMS Interface installation is `SXITRG`.

## Procedure

1. Update the IMS Interface SIP member.
   To change the trigger destination name, specify the changed name in the SIP of IMS Interface.
   Keywords:
   - TRIG-RDQ-NAME
   - TRIG-GDQ-NAME

   Data Set: `USERHLQ.PARM`

   Member: `SXIIIMS1`

2. Specify OTMA Descriptors.
   Perform this step if you require IMS outbound data to be functional.
   You can define OTMA destinations in two methods:
   - Using the D entry: the destinations consist of a name (used as an alternate PCB name, or the target of an ISRT or ICAL command), an XCF member name, and optionally a TPIPE name. The default TPIPE name is the destination name. This method is preferred starting with Release 2.7.
   - Using the M entry: if you have installed the OTMA Destination exit routine, you must include OTMA destination M entries to ensure that the correct OTMA Destination exit routine is called.

   The OTMA descriptors are built during IMS initialization. The descriptors must be included in the `DFSYDTx` members (x is the IMS nucleus suffix) of the `IMS.PROCLIB` data set. For more information, see the chapter on how to tailor your IMS system in IMS System Definition.

   IMS Interface provides a sample descriptors table entry. If you are using the default installation names, you can copy the IMS installation member into your `IMS.PROCLIB` member and make the appropriate edits to the method you are using.

   Data Set: `USERHLQ.PROC`

   Member: `DFSYDT0`

3. Optional: Install TM/MSC Message Routing and Control Exit to support variable-length IMS transaction names.
   Substation ES supports the use of variable-length transaction names, which happens when the default length of 8 characters is not used. Transactions names are specified and not necessarily padded with spaces. For example,

   `"VTRANThis is a message0123456789"`

   where `VTRAN` is the transaction name. Substation ES provides this support through the IMS `DFSMSCE0` exit and a new variable-length specification in the recipe.

   If you already have a `DFSMSCE0` exit active, you must merge the OTMA terminal-routing logic in the Substation-ES-provided exit into your existing `DFSMSCE0` exit.

   Data Set: `USERHLQ.ASM`

   Member: `DFSMSCE0`

   Sample JCL is available for assembling and binding the exit routine.

   Data Set: `USERHLQ.JCL`

   Member: `SXIASMLK`

4. Update the IMS Procedure for the DB/DC Control region.
   If you have placed IMS exit routines in the Substation ES-authorized library, concatenate the load library to the `STEPLIB` DD name of the IMS startup procedure.

   Data Set: `USERHLQ.AUTH`

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