Visual Support for the Modularization of Object-oriented Systems

We introduce a visual approach for nding a good modularization of object-oriented systems. We regard modularization as system partitioning where each class belongs to exactly one module. A good modulariza-tion requires that class dependencies are as local to a module as possible which mirrors the well-known quality principles of strong module cohesion and weak module coupling. In our approach, there are three kinds of (inter-)class dependencies which are explicitly described in a system speciication: (i) relations between classes, (ii) global state invariants constraining the state of several objects belonging to diierent classes and (iii) global system operations which change several objects of diierent classes within one atomic step. As a good modularization is not uniquely determined in general and as there are no common rules for system partitioning, a support for this diicult development task is needed. Therefore, we use an algorithm which takes the class dependencies for clustering classes with strong aanity according to their dependencies and visualize the result as a three-dimensional graph which explicitly represents the class dependencies as vertices and edges. This visualization can be a valuable aid for the developer's modularization decision .