Finding the Compromise – the Adapter Framework - Applied SOA Patterns on the Oracle Platform - page 412

run the test, you will see that all requests are going through the Proxy; check the response
in the OSB console.
One last thing left to complete this quick demo is to add another stage in the response
pipeline, we call it FilterResponse, and add the Java Callout activity. In the Method field,
browse the Client jar, where getRuleAssets() is implemented, and select it as we are
going to invoke it. In the Action field, choose the Expression builder and as an inbound
parameter, select the entire response, and set the output to the new variable in the Result
Value field. Add Replace operation after Callout in this scope and select Replace node
contents (body with XPath expression for Response return value) by variable from the
previous step.
Redeploy it on OSB and run the Client again. You will see the modified results according
your implementation.
This quick and basic demo just demonstrated how easily we can decouple any EJB invoc-
ation using OSB and although it's not really an adapter yet (just a proxy, as explained in
Chapter 4 , From Traditional Integration to Composition - Enterprise Business Services ),
we will further demonstrate how an EJB approach can be used for the dynamic Adapter
framework. As you realize, functionality within the bean can be much more complex than
just filtering the Java list of values. We can encapsulate the entire DB call in a DB-agnost-
ic way.