Building the Core – Enterprise Business Flows - Applied SOA Patterns on the Oracle Platform - page 204

Usage and limitations of a Mediator as a dynamic
router
The primary role of Mediators is to implement the Intermediate Routing SOA pattern in
SOA Suite SCAs, which are the building blocks of either Orchestration (EBF) or Adapter
frameworks. From the SOA Patterns catalog, we know that Intermediate Routing together
with the Service Broker belongs to the ESB compound pattern. So, at first glance, it might
be a bit outlandish to have them both actively discussed in the chapter that is dedicated to
Orchestration. This is the obvious question that arises when someone tries to apply (or
avoid applying) a seemingly fitting pattern, instead of understanding the actual problem
and the ways of its mitigation (not exactly by the pattern with a fancy name from the cata-
log).
The message path in complex compositions could be equally complex, sometimes even un-
predictable at design time, requiring dynamic (or rule-based) dispatching. Oracle SOA
Suite composites (as deployment units) could be really complex, aggregating different
components (primarily presented, but not limited, by four predefined types); the negative
impact of excessive usage of the heavy if-else logic that is implanted into any of
primary components (mainly BPEL) has been clearly explained at the beginning of this
chapter.
The BPEL's dynamic endpoints' invocation approach discussed in the DynamicPartnerLink
example is ingenious but has certain limitations that are mentioned in this paragraph and
the first bulleted list in this chapter. Also, this approach is apparently obsolete with the
presence of SOA Suite SCA 11 g . We need more than just simple WS invocations in our use
case, and Mediator covers them all gracefully.