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.

Abstract : Specification matching is a way to compare two software components. In the context of software reuse and library retrieval it can help determine whether one component can be substituted for another or bow 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. In the context of system interoperability, it can help determine whether the interfaces of two components mismatch. 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, substitutability, subtyping, and interoperability of software components. We write our formal specifications of components in terms of pre-and post-condition predicates. Thus, we rely on theorem proving to determine match and mismatch. We give examples from our implementation of specification matching using the Larch Prover.

Signature matching is a method for organizing, navigating through, and retrieving from software libraries. We consider two kinds of software library components—functions and modules—and hence two kinds of matching—function matching and module matching. The signature of a function is simply its type; the signature of a module is a multiset of user-defined types and a multiset of function signatures. For both functions and modules, we consider not just exact match but also various flavors of relaxed match. We describe various applications of signature matching as a tool for using software libraries, inspired by the use of our implementation of a function signature matcher written in Standard ML.

Software reuse is only effective if it is easier to locate (and appropriately modify) a reusable component than to write it from scratch. We present signature matching as a method for achieving this goal by using signature information easily derived from the component. We consider two kinds of software components, functions and modules, and hence two kinds of matching, function mathcing and module matching. The signature of a function is simply its type; the signature of a module is a multiset of user-defined types and a multiset of function signatures. For both functions and modules, we consider not just exact match, but also various flavors of relaxed match. We briefly describe an experimental facility written in Standard ML for performing signature matching over a library of ML functions.

Miro is a set of languages and tools that support the visual specification of file system security. Two visual languages are presented: the instance language, which allows specification of file system access, and the constraint language, which allows specification of security policies. Miro visual languages and tools are used to specify security configurations. A visual language is one whose entities are graphical, such as boxes and arrows, specifying means stating independently of any implementation the desired properties of a system. Security means file system protection: ensuring that files are protected from unauthorized access and granting privileges to some users, but not others. Tools implemented and examples of how these languages can be applied to real security specification problems are described.>