Request-Invoke-Reply Chain (filterRequestReply)

The Request-Invoke-Reply chain is a representation of the adapter pattern; it applies two separate XSL transformations. This scenario is useful when there are two existing web services which must be integrated even though they have incompatible input and output.

The first existing service acts as a consumer to the XSLT endpoint, sending a request. This message is transformed to match the input of the second service.

The second service is then invoked in an asynchronous manner. When the response from the second service arrives via the NMR, it is transformed to match the expected reply to the first (consuming) service. The sequence of events includes:

1. XML message in

2. XSL transformation of message using first XSL style sheet

3. Invoke service, sending transformed message as input

4. Receive response from invoked service endpoint

5. XSL transformation of response using second XSL style sheet

6. Reply to original sender with transformed third party response