SCA composites

A Service Component Architecture (SCA) composite is a composition unit within an SCA domain. An SCA composite can consist of components, services, references, and wires that connect them. A composite is the unit of deployment for SCA.

The following graphic shows the parts of a composite and its components:

• The blue boxes on the composite represent components. A composite can have one or multiple components.

• A green chevron pointing towards a component represents a service, or business function, that a component provides to its client.

• A purple chevron pointing away from a component represents a reference to a service provided by another component.

• The yellow box on a component represents a property value for a property that is declared by a component implementation.

• The white solid line from the reference of one component to the service of another component represents a wire. A wire between a Component1 reference and a Component2 service indicates that Component1 requires the service provided by Component2.

• An implementation defines a component service in code that is appropriate for the chosen language. Supported implementations include Java Pojo and SCA composites.

An application can contain one composite or several different composites. The components of a composite can run in a single process on a single computer or be distributed across multiple processes on multiple computers. The components might all use the same implementation language, or use different languages.

An SCA composite is typically described in a configuration file, the name of which ends in .composite. The following graphic shows the composite definition of the helloworldws composition unit in the SCA sample application HelloWorldAsync. We can find the composite definition for the helloworldws composition unit in the /META-INF/sca-deployables/default.composite file.

A composite file in a WAR file must be named default.composite. A composite file that is not in a WAR file can have any name.

The product supports composite as an implementation, as described in Section 1.6 of SCA Assembly Specification 1.0. See "Unsupported SCA specification sections" for information on parts of Section 1.6 that the product does not support.