Service components

A component consists of an implementation and one or more interfaces, which defines its inputs, outputs, and faults, and also its references, if applicable. A reference identifies the interface of another service or component that this component requires or consumes. An interface can be defined in a WSDL port type language or in Java™. An interface supports synchronous and asynchronous interaction styles. A component's implementation can be in various languages.

The recommended interface type is WSDL, which is the language used by the provided tutorials and samples. A Java interface, however, is supported and used mostly in the case when a stateless session EJB is imported (discussed later in Imports and exports). If you define a component and add the Java implementation later, you should still use a WSDL interface. You cannot mix WSDL-interface-based components with Java interface-based components.

In the picture below, we have a component in the center. It's implementation, MyValueImpl, is in Java as is its interface. It has two references: another Java interface and a WSDL interface.

When you are working with a component, as shown in the following diagram, you see only the component itself. A reference to this component from another component appears as a line to its interface. A reference from this component would be revealed by a line from its reference point to the interface of other component. A reference represents a service that this component consumes. When you name a reference and specify its interface only, you allow the component implementation author to defer binding that reference to an actual service until later. The ability to defer binding and reuse implementations is one of the key reasons for using IBM® Integration Designer's Service Component Architecture.

A component might also have properties and qualifiers. A qualifier is a quality of service (QoS) directive on interfaces and references for the runtime environment.