Modifying an IMS application for callout requests

You must modify your IMS application in order to place the callout request on the OTMA hold queue or route the request to an IMS Connect destination.

To modify your IMS application to issue a callout request:

  1. Place the callout request in an IMS Connect destination that is defined in an OTMA destination descriptor.
    • For a synchronous callout request, your IMS application must issue an ICAL call to place the callout request on an IMS Connect destination that is defined in an OTMA destination descriptor.

      Start of changeIn IMS 14 or later, in the ICAL call, you can specify in the control data area the XML converter or the request routing information to override what is defined in the OTMA destination descriptor and in the web service WSDL or correlator file. End of change

    • For an asynchronous callout request, Your IMS application must specify an ISRT ALTPCB call to place the callout request on the OTMA asynchronous hold queue or to an IMS Connect destination that is defined in an OTMA destination descriptor.
  2. If a response message is expected from the external application, correlate the response.
    • For a synchronous callout request, SOAP Gateway handles the correlation of the response to the corresponding callout request.
    • For a asynchronous callout request:
      • You might need to correlate the response back to the initial request message or to a different transaction for further processing.
      • You must specify the transaction code for the IMS transaction that will process the output response. In most cases, you should invoke a non-response mode IMS transaction to process your response message. If you specify a response mode transaction to process the response message, the output of the response mode transaction will be routed to the IOG$RESP tpipe.

    The best way to correlate the response in your IMS application might be to define some data, such as a message identifier or a unique request ID, in your callout request that can correlate with the initial input message. You might also have the IMS application program that issues the callout request store correlation data or other data in an IMS database for retrieval when the callout response is returned.

    For more information on the callout function and correlation of the data, see the Callout requests from IMS application programs topic in IMS 14 Communications and Connections information.

  3. See Selecting the data transformation process for callout messages for more information about why and how to decide on the data transformation process.
  4. If you are not using the IMS Connect XML adapter to convert the callout request and response data between bytes and XML, you need to handle the data transformation in your application by preparing your own callout messages.