Ensuring Compatible Interactions within Component-based Software Systems

The interface definition of a component in a distributed system forms the contract between the component itself and its neighbouring components regarding the use of its services. In general, such a contract should cover the issues of service functionality, usage and quality. The Interface Definition Languages (IDLs) used by commercial middleware standards such as CORBA primarily address the signature issues of such a contract, i.e., the forms and types of component or object services. Nothing is said about other aspects of the contract, including the way in which the component services are to be used. In this paper, we introduce a framework and associated techniques that augment commercial IDLs with interaction protocol specifications and validate component interactions against such protocol specifications at run-time. In effect, the validation becomes a useful tool for testing whether or not the object services are used properly in a distributed system. Our approach has been implemented in the CORBA context, but can be readily applied to other IDL-based object/component systems.