A behavioural algebraic framework for modular system design with reuse

Abstract

A formal framework for the design of modular software systems is presented which incorporates the idea of reusing software components in new applications. The approach is based on structured algebraic specifications with behavioural semantics. In order to provide a clean interconnection mechanism for specifications, behavioural specifications with import interfaces are considered and their composition with respect to the behavioural requirements of the import interface is defined. A simple implementation notion for behavioural specifications with import interface is presented which is compatible with the composition of specifications. Hence it is guaranteed that separately developed implementations of parts of an abstract system specification can be automatically composed to a globally correct system implementation. Based on these concepts, reusable components are defined as (unordered) trees of behavioural specifications with import interfaces such that two consecutive nodes are related by the implementation relation. A formal method for the systematic reuse of components in new applications is proposed. The method consists of four steps which describe how to construct for a given abstract system specification a modular implementation by reusing existing implementations available as leaves of appropriate reusable components. The method is demonstrated by a detailed example.

This research has been partially sponsored by the German BMFT-project KORSO