Supported scenarios and features
SOAP Gateway supports two usage scenarios: web service provider and web service consumer.
Web service provider scenario
An IMS application can be enabled as a web service that provides services or data to service requesters.
When an IMS application is deployed as a web service provider, the SOAP Gateway server receives the SOAP message from the client application, converts it to an IMS input message, and sends it to IMS. The server then receives the output message from IMS and converts it to a SOAP message to return to the client.
With the tooling support in IBM® Rational® Developer for System z®, the required web services description language (WSDL) file and XML converters can be generated from an COBOL or PL/I application. This approach is known as the bottom-up development scenario in Rational Developer for System z. You can also create a WSDL file that describes the web service in Rational Developer for System z, and then use the top-down development scenario in Rational Developer for System z to generate a PL/I application. The PL/I application can then be deployed to IMS, and enabled as a web service on SOAP Gateway by using the same WSDL file that was used to generate the application.
Web service consumer scenario
An IMS application can issue a callout request to a web service through SOAP Gateway. When an IMS application is enabled as a web service consumer, it can invoke either a one-way web service operation or a request-response operation. The IMS application uses different calls to initiate a web service request and to indicate, if a response is expected, whether the response is to be processed in the same transaction (also known as synchronous callout) or a different transaction (also known as asynchronous callout).
When an IMS application is deployed as a web service consumer, the SOAP Gateway server checks with IMS Connect to determine if any callout request messages are in the hold queue. When the server receives an IMS callout request from IMS Connect, SOAP Gateway parses the message and converts it to a SOAP message to invoke the web service. If a response is returned from the web service, SOAP Gateway converts the SOAP message and sends the response to IMS by invoking a new IMS transaction using the send-only protocol. Alternatively, SOAP Gateway can use the send-only protocol with acknowledgement to request a final acknowledgement from IMS that the message was received. The final acknowledgement message is not passed to the client application.
With the tooling support in Rational Developer for System z, you can generate the required XML converter and the correlator file by mapping the input and output data between the web service WSDL file and the IMS application. This approach is known as the meet-in-middle development scenario in Rational Developer for System z.