The descriptor theory-what is it about?

The flowgraph theory of N.E. Fenton and R.W. Whitty (1984) defines how to map program structure onto flowgraphs. What is the aim? The goal they want to reach is the usage of flowgraphs as a sound basis for measuring certain aspects of complexity. This measurement is, due to the chosen basis, done in an objective way. The aspects of complexity measured depend on the respective application, i.e. the kinds of complexity needed to get the results demanded by the user. But putting the flowgraph theory described in this paper into practice reveals some weak points which destroy the general applicability of this theory. This is the reason why we developed a model, which is in fact still based on the flowgraph theory but enhanced by so-called descriptors. This enhancement makes it possible to handle programming as well as specification languages. As a consequence we are able to measure formal descriptions of both types in an objective way with the help of the same constructs and theories. The work was carried out as part of an ESPRIT II project COSMOS (Cost Management with Metrics of Specification)