Optimisation Process for Maintaining Evolvability during Software Evolution

Software systems have to be changed continuously and evolutionarily throughout the whole time of their development and usage. Meanwhile, the software systems have to remain flexible in order to retain the ability to be extended by additional new features or to be changed. To maintain this ability, known as evolvability, the architecture of such software systems and its evolution must be continuously controlled and, if necessary improved. Existing design methodologies do not provide sufficient support for controlling the evolvability. One reason for this is, that in comparison with software maintainability, evolvability characteristics are hardly defined. This paper discusses evolvability, and introduces a quality model for it. Furthermore, a meta-model-based process for controlling and optimising the evolvability characteristics of software baselines is presented. The feasibility of this approach is shown by a case study based on the results from its implementation in large industrial projects.