Interacting Frameworks in Catalysis

In current OO Design, most of the existing (semi-formal) methods use classes or objects as the basic unit of design. However, it is increasingly recognised that classes are not the best focus for design. Typical design artefacts are about groups of objects and the way they interact. In the Catalysis project, we use the term frameworks for descriptions of groups of objects, their relationships, division of responsibilities, and interactions. The power of frameworks lies in the fact that interactions can also occur at the level of frameworks. In a previous paper, we defined a framework formally as a (first-order) many-sorted theory with a modeltheoretic semantics and showed how it can be represented using a pictorial notation for practical system development. However, we considered only frameworks that do not interact with one another. In this paper, we discuss frameworks that interact with one another, and show that such frameworks are very powerful tools for formal OO Design.