Retrieval in a module library using formal specifications: Preliminary search using syntactic properties

Abstract

The paper addresses a problem that is urgent in industrial software manufacturing: the retrieval of reusable software components in a module base. Given the formal specification of a software task and a library of software modules together with their formal specifications (specification base), how to identify the modules that come closest to satisfying the task. It is argued that the problem is best solved in a stepwise fashion, where the first few steps deal entirely with the syntactic aspects of the specifications and the final steps with their semantic aspects. The paper concentrates on the former. Based on the specification technique of Operational Replacement Schemes (a close relative of algebraic specification techniques), a sequence of search steps are introduced starting with the comparison of some simple characteristics, and ending with a decision procedure on structural equivalence. Each step uses symbolic computation and resolution techniques. The discussion is mainly restricted to isomorphic specifications, some aspects of ‘similarity’ between specifications are outlined in the paper's conclusions.