Managing Evolution Using Cooperative Designs and a Reflective Architecture

The separation of concerns is important to attain object oriented systems which can be easily evolved. This paper presents a reflective architecture which enforces the separation of concerns by allocating functional, interaction and synchronization code to different levels. A variant of collaborations (CO actions) is used to capture interactions between objects and avoids spreading the description of interactions among the participating objects. Functional and interaction code are also separated from synchronization code by means of metalevel components. Introducing changes into the reflective architecture to consider evolution needs is facilitated by the loose coupling of different concerns. Hence, changing a concern often consists of modifying only one component of the reflective architecture. The paper describes the reflective architecture in terms of a case study. The evolution of the reflective implementation of the case study is compared with the evolution of an alternative implementation and the benefits of the proposed architecture are shown by using an evolution metric.