Invoking an adapter service using a CICS-supplied interface

You can use the External Call Interface (ECI), External CICS® Interface (EXCI), or Distributed Program Link (DPL), potentially via CICS Transaction Gateway (CTG) or a distributed version of CICS, to invoke an adapter service. When you use a CICS-supplied interface, the request can only be processed in synchronous mode.

  1. Select the interface that is appropriate for your service requester.
    1. If you want to use CTG to invoke the adapter service, use the ECI interface. However, if CTG is installed on z/OS®, the EXCI interface is actually used.
    2. If you want to use DPL, use the EXEC CICS LINK command to link from the service requester to the DPL stub program with a request message. If you opt for DPL, you can use a channel and containers to pass the request message, rather than a COMMAREA.
  2. Decide what data conversion is required. It might be necessary to perform data conversion in the CICS Service Flow Runtime routing region, using a customized version of the standard CICS conversion table DFHCNV. For details, see Data conversion.
  3. Decide how you want to send the request message from the service requester to invoke the adapter service. The service requester can send the message in a COMMAREA, or if you are using DPL a set of containers. The service requester then waits for a response if required.
  4. When the adapter service has completed its processing of the request message, the DPL stub program passes the response message back to the service requester. The CICS-supplied interface requires a response, but the request message might not require an application reply.