Concurrent Object-Oriented Design Specification in SPECTRUM

In this paper an algebraic approach to formal object-oriented design specification is presented where the static and functional part of a software system is described by classical algebraic specification whereas the dynamic behavior is modeled by a transition relation. The approach is inspired by Astesiano’s SMoLCS formalism and is based on Meseguer’s rewriting logic; but it has two additional features, which are motivated by pragmatic objectoriented software development techniques: it supports the construction of subsystems, and the flow of messages can be controlled by use of a simple but powerful concurrent language. Liveness and safety properties of design specifications are formulated with the help of structured message expressions; methods for proving such properties are shortly discussed. As underlying specification language Broy’s SPECTRUM is extended by features for concurrent object-oriented specification. An example of a component for interactive sorting is given and liveness and safety properties of the component are proven.