Non-invasive and non-scattered annotations for more robust pointcuts

Annotations are often mentioned as a potential alternative to tackle the fragile nature of AspectJ pointcuts. However, annotations themselves can be considered crosscutting elements because they are normally pervasive and tangled with business-specific functionality. In this paper, we propose a solution to the fragile pointcut problem in aspect-oriented programming that relies on non-invasive and non-scattered annotations. The central components of the proposed solution are so-called annotator aspects, that superimpose annotations to the base code in a non-invasive way. Moreover, annotator aspects are generated semiautomatically, from a declarative annotation definition language. The paper presents examples of using the proposed solution in pointcut descriptors of two real-world aspect-oriented systems. We also describe a case study that evaluates the robustness of the proposed solution in face of possible changes to the classical Figure Editor system.