Study of Dependence Matrix for Assessment of Object-Oriented Software Design Quality

The purpose of this paper is to evaluate if software metrics can be used in software development process to improve the design quality of the software system. One of the earliest software product quality models was suggested by McCall and his colleagues. It defines software product quality as a hierarchy of factors, criteria and metrics. ISO developed a standard for software product quality, ISO 9126, which is on the same line. Problem with these models is that they are vague in their definition of lower level attributes and metrics needed to attain a quantitative assessment of product quality. Recently, a framework for building product based quality models has been developed by Dromy which addresses some of the problems of earlier models. This paper takes up two approaches in parallel to evaluate the quality of Object-Oriented Software System. The first approach extends the concept of dependence matrix of modular programming to OO Systems. Coupling measure is calculated comprehensively for all possible combination types of interactions among classes. These interactions may occur due to inheritance, friendship or containership (whole-part) relationships and may be different types e.g. class-attribute interaction, class-method interaction and method-method interaction. Interactions are also distinguished by locus of impact: i.e. whether the impact of change flows towards a class (import) or away from class (export). Next, all five of cohesions are considered to obtain the cohesion measure. Using these two, first order dependence matrix and complete order dependence matrix are calculated which gives expected change measure and overall design measure.