Databases Reference
In-Depth Information
The diagram illustrates the deployment of multiple composite applications on to
the 11
g
service infrastructure, with each composite application composed of
multiple composites. In other words, a composite application is a collection of
composites that have been designed and implemented as part of the same solution
(for example, oBay).
From this, we can see that each composite application is made up of a combination of
virtual services, business services, and business processes.
The diagram also depicts a number of virtual services deployed to the Oracle Service
Bus. These virtual services implement the internal and external virtual service layer.
An obvious question that this prompts is when to implement a virtual service in a
composite, and when to implement it using the OSB.
It's worth recalling that the function of the virtual services layer is
NOT
about
implementing a new service, but rather we are providing a layer of abstraction over
an existing service. In other words, the focus of this layer is all about decoupling the
service consumer from the service provider.
This, of course, is the primary objective of the Oracle Service Bus, so should be the
default technology for implementing this layer. The reality is that it's not that simple
and there are a number of scenarios where it makes sense to implement these (using
a Mediator) within a composite, which we will highlight over the following pages.
