Inquire: predicate-based use and reuse

There are four fundamental aspects of use and reuse in building systems from components: conceptualization, retrieval, selection and correct use. The most important barrier to use and reuse, initially at least, is that of conceptualization. The Inscape Environment is a specification-based software development environment (SDE) integrated by the constructive use of formal interface specifications. The purpose of the formal interface specifications and the semantic interconnections (created and maintained as software is built and evolved) is to make explicit the invisible semantic dependencies that result in conventionally built systems. The important ingredient provided by Inquire in conceptualization, retrieval, selection and use is the set of predicates that describe the semantics of the elements in the interface. These predicates define the abstractions that are germane to the module interface and describe the properties of data objects and the assumptions and results of operations in a module. Use and reuse of components is based on a component’s ability to provide needed semantics — either in terms of data object properties or in terms of operation behavior — at a particular point in a system. It is the purpose of Inquire, the browser and predicate-based search mechanism, to aid both the environment and the user in the search for the components that will provide the desired predicates — that is, the desired properties or behaviors — that are required to build and evolve an implementation correctly. 1.