Flexible user interface coupling with operation transformation

This thesis presents new results in multi-user interface coupling, consistency control and adaptive object sharing. These new results are specifically designed to function effectively over wide area networks with emphasis clearly placed on performance over the Internet. Filtered interface coupling is a new technique for the controlled coupling of multiple user interfaces. The technique allows users to dynamically adjust coupling between user interfaces. A new extensible operation transformation based consistency scheme is used to maintain the consistency of shared user interfaces. The operation transformation scheme uses a new adaptive object sharing technique that supports adaptive data location to improve performance on high latency networks. The three results, while not being interdependent, function most effectively when used in combination. An introduction to the fundamental issues in collaborative systems is presented. Prior work in collaborative systems with particular emphasis on World Wide Web enabled tools is presented. Prototype implementations of the new collaboration algorithms are presented along with measurements of the performance and behavior of the prototypes. The prototypes were developed within the Shastra collaborative system, a web based collaboratory.