Combining Component Specifications in Object-Z and CSP

Abstract.

This paper discusses the separation of components from the contexts in which they are used, and how this separation can be supported whilst using different specification languages. There are a number of ways in which this might be possible and here we show how the technique of promotion in Object-Z can be used to combine components which are specified using process algebras. We outline two approaches. The first is to separate out a single specification into a number of distinct viewpoints (i.e., partial specifications), each possibly written in a different notation. These viewpoints can be developed separately, but combined if necessary by a process of translation and unification. The alternative approach we discuss is to use a single hybrid language which is composed of a combination of notations, which we illustrate here by combining CSP and Object-Z. We illustrate both approaches with a simple example, and also consider how such component-based descriptions can be refined, which involves addressing the question of compositionality.