Recording, processing, and visualizing changes in diagrams

In this paper, we present methods and techniques to record, process, and visualize diagram changes. These methods help us understand diagram changes, and are the basis for more enhanced functionality, such as a more powerful undo functionality, or merging of different versions of a diagram. Our approach is based on the idea to record all diagram changes, including changes of the diagram layout. One of the main challenges is to provide a concise and comprehensible visualization of these changes. In order to produce such a visualization, the recordings need to be processed, comprising filtering and aggregation of changes. Our model-based approach is generic and makes use of the abstract and the concrete syntax (meaning and representation) of the specific diagram language.