Chapter 7. Mediator Service for Straight Talk and No Nonsense

Now that we have introduced BPEL as a service component type, we will move on to another SCA component type that often works together with BPEL components: the Mediator. This is an important component in the SOA Suite that takes on some of the core responsibilities described in Part I for the enterprise service bus.

Under close scrutiny, one could argue that all that is happening in SOA composite applications is a more or less constant flow of XML messages—for example, the incoming request message that flows to a service component, one or more messages from that service component that flow to adapter services or other service components, and eventually a response message that flows back to the invoker. Mediator components facilitate these XML message flows in composite applications—by performing validations, transformations, both content- and header-based routing and filtering on messages, as well as adaptation from synchronous to asynchronous, and vice versa, and various other operations.