A quantitative framework for software restructuring

Many existing software systems can benefit from restructuring to reduce maintenance cost and improve reusability. Yet, intuition-based, ad hoc restructuring can be difficult and expensive, and can even make software structure worse. We introduce a quantitative framework for software restructuring. In the framework, restructuring decisions are guided by visualized design information and objective criteria. The design information can be extracted directly from code to restructure existing or legacy software. Criteria for comparing alternative design structures include measures of design-level cohesion and coupling. Restructuring is accomplished through a series of decomposition and composition operations which increase the cohesion and/or decrease the coupling of individual system components. An example and a case study demonstrate the framework. The framework ensures that restructuring results in measurable improvements in design quality. Copyright © 1999 John Wiley & Sons, Ltd.