Specification matching of software components

Abstract

Specification matching is a way to compare two software components, based on descriptions of the component's behaviors. In the context of software reuse and library retrieval, it can help determine whether one component can be substituted for another or how one can be modified to fit the requirements of the other. In the context of object-oriented programming, it can help determine when one type is a behavioral subtype of another. We use formal specifications to describe the behavior of software components and, hence, to determine whether two components match. We give precise definitions of not just exact match, but, more relevantly, various flavors of relaxed match. These definitions capture the notions of generalization, specialization, and substitutability of software components. Since our formal specifications are pre- and postconditions written as predicates in first-order logic, we rely on theorem proving to determine match and mismatch. We give examples from our implementation of specification matching using the Larch Prover.