Using Recovered Views to Track Architectural Evolution

Tracking the evolution of a software system through time gives us valuable information. It suggests which parts are likely to remain stable and which ’problem’ aspects are likely to change, and it gives us insight into some of the design choices made. In this paper we show how recovered views of succesive versions of the same software system can be used to track evolution. We first briefly describe our approach for recovering views of software applications. We then compare views of two versions of the HotDraw framework. Our objective is to illustrate a number of issues concerning architectural evolution: what is architectural change as opposed to change in general? how can we detect architectural drift? how can we evaluate the relative quality of different architectural solutions? what are guidelines for building evolvable software?