Automating the Evolution of Object-Oriented Systems

A formal framework is presented for maintaining behavior and consistency of object-oriented systems during software evolution. The framework effectively couples a change avoidance approach based on Adaptive Object-Oriented Software with a change management mechanism to fully automate evolution. Schema transformations may render existing objects and programs inconsistent. The framework identifies the introduced inconsistencies and provides the necessary object and program transformations to reinstate consistency while maintaining the behavior of the system. A formal definition of behavioral equivalence is given. To prove behavioral equivalence of adaptive programs, the paper includes a formal semantics for adaptive software. Finally, the feasibility of the framework is demonstrated for a representative set of primitive schema transformations.