A generic approach to supporting diagram differencing and merging for collaborative design

Differentiation tools enable team members to compare two or more text files, e.g. code or documentation, after change. Although a number of general-purpose differentiation tools exist for comparing text documents very few tools exist for comparing diagrams. We describe a new approach for realising visual differentiation in CASE tools via a set of plug-in components. We have added diagram version control, visual differentiation and merging support as component-based plug-ins to the Pounamu meta-CASE tool. The approach is generic across a wide variety of diagram types and has also been deployed with an Eclipse diagramming plug-in. We describe our approach's architecture, key design and implementation issues, illustrate feasibility of our approach via implementation of it as plug-in components and evaluate its effectiveness.