Specification matching of state-based modular components

Retrieval of software components from a library relies on techniques for matching user requirements against library component interfaces. Here we introduce a number of techniques for matching formally specified, state-based modules. These techniques will form the basis for retrieval tool support. The techniques described are built on existing specification matching methods, based on individual functions, specified using pre- and post-conditions. We begin by defining a basic module matching technique, based on matching the individual units within a module. We consider variations of this technique that take into account two important features of modules: the visibility of module entities; and the use of state invariants. An advanced technique, based on data refinement and the use of coupling invariants, is also described.