Maintainability assessment in object-oriented system design

The maintenance of existing software can account for 60 percent of all effort expended by the resources used in the system development life cycle. To improve the situation, analysts must design system that easy to maintain at the early stage of the development process. At the design phase, an object-oriented system is decomposed into subjects. Each subject is decomposed into subsystems. A maintenable o-o system is a system where the change affect a less number of subsystems. In this work, a maintainability metric is proposed. This metric measures the localization of a change at the design phase.