Lessons Learned on Design for Modifiability and Maintainability

Maintainability is perhaps one of the most important aspects of software development in that maintenance costs account for at least 50% of software system lifetime costs. A common maintenance practice is adding new capabilities to satisfy the evolving system dynamics, thus contributing to the ever-growing expenses. This paper discusses some lessons learned from system modifiability that affect software maintainability from the design standpoint. Deciding which design approach is most appropriate for the underlying system requirements plays a major role in software product operability and extensibility. keywords: design for change, maintainability, modifiability, software IC.