Databases Reference
In-Depth Information
As can be seen in the preceding screenshot, an SCA composite consists of several
different parts.
Component
A component represents a piece of business logic. It may be process logic, such
as a BPEL process, routing logic, such as a mediator, or some other SOA Suite
component. In the next section, we will discuss the components of the SOA Suite.
SCA also supports writing custom components in Java or other languages, but we
will not cover that in this topic.
Service
A service represents the interface provided by a component or by the SCA
Assembly itself. This is the interface to be used by clients of the assembly or
component. A service that is available from outside the composite is referred
to as an
External Service
.
Reference
A reference is a dependency on a service provided by another component, another
SCA Assembly, or by some external entity such as a remote web service. References
to services outside the composite are referred to as
External References
.
Wire
Services and references are joined together by wires. A wire indicates a dependency
between components or between a component and an external entity.
It is important to note that wires show dependencies
and not flow of control. In the example, the
Mediator
component may call the
FileWriteService
before or
after invoking BPEL, or it may not invoke it at all.
Composite.xml
An SCA Assembly is described in a file named
composite.xml
. The format of this
file is defined by the SCA standard and consists of the elements identified in the
preceding screenshot.
