A Group Undo/Redo Mechanism to Preserve User Intention in Replicated Collaborative Modeling Systems

Undo/redo mechanism is an important issue in interaction-centered CAD system. Since the design task is a creative process, the users of CAD systems have to use undo/redo mechanism to repeatly modify the CAD model in order to achieve a satisfied result. However, undo/redo mechanism is not an easy work even in standalone CAD systems. This is the reason why different commercial CAD systems are equipped with different level of undo/redo mechanism. Therefore, group undo/redo mechanism in collaborative system becomes a special challenge. This paper proposed a group undo/redo method in replicated collaborative modeling system. In our method, one user’s operation intention can be preserved in both local site and remote sites. The preservation is based on dependency relationship among users at different sites. The implementation of the Undo/Redo operation in both local site and remote site is described in detail respectively. The proposed approach has been tested in a prototype system with case study. The authors believe that this work represents the first attempt to address group undo/redo mechanism in collaborative CAD systems.Copyright © 2009 by ASME