Software Process Improvement

Abstract

Little theory exists in the field of software system measurement. Concepts such as complexity, coupling, cohesion or even size are very often subject to interpretation and appear to have inconsistent definitions in the literature. As a consequence, there is little guidance provided to the analyst attempting to define proper measures for specific problems. Many controversies in the literature are simply misunderstandings and stem from the fact that some people talk about different measurement concepts under the same label (complexity is the most common case).There is a need to define unambiguously the most important measurement concepts used in the measurement of software products. One way of doing so is to define precisely what mathematical properties characterize these concepts, regardless of the specific software artifacts to which these concepts are applied. Such a mathematical framework could generate a consensus in the software engineering community and provide a means for better communication among researchers, better guidelines for analysts, and better evaluation methods for commercial static analyzers for practitioners.In this paper, we propose a mathematical framework which is generic, because it is not specific to any particular software artifact, and rigorous, because it is based on precise mathematical concepts. This framework defines several important measurement concepts (size, length, complexity, cohesion, coupling . IntroductionMany concepts have been introduced through the years to define the characteristics of the artifacts produced during the software process. For instance, one speaks of size and complexity of software specification, design, and code, or cohesion and coupling of a software design or code. Several techniques have been introduced, with the goal of producing software which is better with respect to these concepts. As an example, Parnas [P72] design principles attempt to decrease coupling between modules, and increase cohesion within modules. These concepts are used as a guide to choose among alternative techniques or artifacts. For instance, a technique may be preferred over another because it yields artifacts that are less complex; an artifact may be preferred over another because it is less complex. University of Maryland CS-TR-3368 -2 definition of relevant concepts (i.e., classes of software characterization measures) is the first step towards quantitative assessment of software artifacts and techniques, which is needed to assess risk and find optimal trade-offs between software quality, schedule and cost of development.To capture these concepts in a quantitative fashion, hundreds of software measures have been defined in the literature. However, the vast majority of these measures did not survive the proposal phase, and did not manage to get accepted in the academic or industrial worlds. One reason for this is the fact that they have not been built using a clearly defined process for defining software measures. As we propose in [BMB94(b)], such a process should be...