Formal Foundations for Reasoning about Evolution

Designing software systems is difficult. Designing systems that are capable of evolving is even more difficult. Often the system evolves in an unforeseen direction. Practice shows that software systems grow in small evolutionary steps. An evolution usually influences the behavior and the structure of the system. However, it is not desired that the evolution influences one or more modules of the system that are functionally or logically not related to the evolution; the behavior and structure of these modules should be preserved. In this position paper, we introduce an algebra as a formal foundation for reasoning about evolution. The algebra can be used to express changes in the behavior and structure of the design when it evolves. The aim is to eventually use the algebra to give decision support to the developer during the evolution of a software system. This position paper can be grouped in: Formalization of AOSD, Design Support for AOSD, Visions and Directions This work has been funded by the EU-funded IST Project 1999-14191 EASYCOMP