• TMEMBER, to identify which OTMA client to send the message to
• MQRTQMGR, to identify which WebSphere MQ reply queue manager will process the message
• MQRTQ, to specify the WebSphere MQ queue for the message. 

Setting MQMD Options

Messages sent to WebSphere MQ require an MQMD header. Prior to IMS 13, you had to code OTMA exit routines in Assembler to build and define the MQMD headers. In IMS 13, you can specify MQMD values in an OTMA destination descriptor and OTMA will build the MQMD headers for you.

You can still use the OTMA routing exit routines to modify the values specified in the OTMA destination descriptors.

Reusing the MQMD Structure

If a transaction message that was originally received from WebSphere MQ starts as an asynchronous callout request, you can have IMS create the MQMD for the asynchronous callout message from the MQMD of the input message by specifying MQCOPYMD=Y in the OTMA destination descriptor.

All of the MQMD fields from the input message are copied to the callout message. Any MQ specifications in the OTMA destination descriptor that differ from the original MQMD specifications override the original MQMD values. 

Setting MQMD Values

The WebSphere MQ application uses some of the parameters you can specify on the OTMA destination descriptor (such as MQMSGID, MQCORRELID and MQAPPLID) to selectively retrieve from the queue only those IMS callout messages that match certain criteria.

The parameters in the OTMA destination descriptor WebSphere MQ uses correspond to parameters WebSphere MQ defines. For example, the MQREPORT parameter corresponds to MQMD_REPORT. This parameter is used to tell WebSphere MQ how to manage the MQMSGID and MQCORRELID values. The values you specify for these options must work with the WebSphere MQ application that will retrieve the messages.

If the transaction that issued the asynchronous callout message was initiated from WebSphere MQ and you specify MQCOPYMD=Y, then IMS copies the values for MQMSGID and MQCORRELID from the MQMD_MSGID and MQMD_CORRELID fields in the original MQMD. These values will be overridden if MQMSGID or MQCORRELID are coded in the OTMA descriptor.  

You can specify several options on the MQREPORT keyword in the OTMA destination descriptors. Here’s a list, with the name of the value as it’s defined in WebSphere MQ shown in parentheses:

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