Refactoring is a well known software development technique that can bring several bene ts to aspect- oriented applications by allowing developers to introduce aspects to an existing object-oriented program as well as changing the aspect-oriented program itself. Aspect-oriented developers have been identifying common transformations, but they sometimes lack support for assuring that the transformations preserve behavior and are indeed refactorings. This book focuses on that problem and introduces AspectJ programming laws that can be used to derive or create behavior preserving transformations...