Ready For Evolution : Designing Evolution Aware Components in Java

Change in software systems is inevitable, and occurs as mistakes are discovered in the initial design, or as part of incremental design. In current multi-component systems, upgrading systems and consequently discovering what components are effected by a given change is hard, and cannot be handled in an automated manner. This is mainly due to the fact that building software systems using current component technology introduces a tangled web of component dependency. All components in the system must be examined when the system is evolved in such a scenario, in order to propagate the change to all effected components. To address this component dependency problem from a software evolution perspective, we propose a Component-Connector-Contract (3C) Architecture. This architecture provides (1) the isolation of behavior and interaction between components; and (2) contracts for each method. The 3C architecture thus facilitates automated software evolution by (1) providing a loose coupling of behavior and interaction between components; and (2) providing different levels of dependency of components, thereby reducing the search space for all components effected by a change. In this paper, we provide an overview of the 3C architecture and show how the de-lineation between behavior and interaction can be implemented using the current Java standard and JML.