From Traditional Integration to Composition – Enterprise Business Services - Applied SOA Patterns on the Oracle Platform - page 290

declare variable $request as element(*) external;
xf:XQ_Request_GAdapter_Route($request)
That's it. You can extend this list as much as you want and build your own adapters by im-
porting the JCA and WSDL files from the SCA adapter composite. Respect the contract-
first principle. Bear in mind that lots of parameters can be passed to the adapter itself;
even the JNDI name that you give in SCA can be declared as a variable (view it as a prop-
erty in composite.xml for related BPEL) and managed dynamically or via System
MBean Browser in soa_domain (WLS console). The sequence of actions for the DB
adapter, for instance, could be as follows:
• Transport Data Adapter receives CTUMessage as an input with JCA properties
• Adapter extracts data source name and SQL statement
• Adapter calls the XQuery executing fn-bea:execute-sql()
For your Service Broker, we recommend that you build this list gradually, starting from
the most common and generic adapters: HTTP/SOAP first. Some adapters are not simple
like for JSON payload, where some Java coding will be necessary to remap XML to the
JSON format.
Conclusion - the pros and cons of OSB Agnostic Composition Controller
We separated the synchronous part of our Agnostic Composition Controller and moved it
away from SCA. Now, our asynchronous Service Broker in SOA Suite looks much more
concise and modular, and all synchronous service interactions are delegated to the EBS
Framework where they belong. You can clearly see the resemblance in implementation
steps for Message Broker and Service Broker, but the difference is quite distinguishable:
• Just look at the list of transport protocols we can support (yes, they are all JCA
adapters, but they are pretty standard).
• Although some coding efforts are still required (XQuery for instance), it is com-
parably less than the custom servlet-based approach.
• Dynamic Routing, Invocation, and Transformation is really handy.
• Most importantly, by following the contract-first approach, we delivered a modu-
lar solution! The concept of Proxy Service allows us to gracefully assemble truly
loosely coupled components. We have highly manageable and completely de-
coupled layers that are based on patterns (SOA and EAI), namely Business
Delegate, Service Broker, Adapter Factory, and Adapters.
• EAI and JEE patterns are not dead (as you probably heard on some SOA sym-
posiums). Appropriately applied on the service composition level, they can im-