Interaction Refinement in Object - Oriented Systems ( Extended

An OO designer typically starts with a high-level idea of the interactions between the key objects in the system. As the design progresses, the designer refines these interactions by identifying the exact operations of each object that other objects will invoke and the order of invocations, or by introducing new objects with appropriate operations to mediate the required interactions between existing objects, etc. These refinements are usually not recorded, so the rationale behind the design maybe lost. We motivate the notion of interaction refinement with a few examples, provide a precise definition of the concept, and develop a formalism that can be an important tool in recording and validating OO designs.