Structure and Interaction: Architectural Abstractions NOSA'98

Problem. An object-oriented software system consists of set of objects that interacts through a set of messages or method invocations. Throughout a system's lifetime objects gets created and garbage collected, thus a system is very dynamic in both its behaviour and con guration. Even with small or medium sized systems the complexity caused by the number of objects and method invocations makes it hard to describe and reason about the system. Especially it gets hard to understand how the di erent objects are related at run-time: the structures and collaboration patterns they participate in. On the other hand these structures and collaborations are considered the hardest parts to get right when designing new systems, hence it is desirable to reuse successful examples. Patterns [2] and frameworks [5] are examples of object-oriented techniques that has been proposed to counter these problems. In our approach we seek alternatives, prompted by the fact that both patterns and frameworks describe much more than just architecture. The development and application of patterns and frameworks is not our primary concern.