Bounding Component Behavior via Protocols

In this paper we enhance the SOFA Component Description Language with a semantic description of a component's functionality. There are two key requirements this description aims to address: First, for the design purpose, it should ensure correct composition of the nested architectural abstractions; second, it should be easy-to-read so that an average user can identify a component with the correct semantics for the purposes of component trading. The semantic description in SOFA expresses the behavior of the component in terms of behavior protocols using a notation similar to regular expressions which is easy-to-read, and which grants guarantees about required and provided services. The behavior protocols are used on three levels: interface, frame, and architecture. One of the key achievements of this paper is that it defines a protocol conformance relation where the component designer can statically verify that the frame protocol adheres to requirements of the interface protocols, and that the architecture protocol adheres to the requirements of the frame and interface protocols.