Responsiveness and consistency tradeoffs in interactive groupware

Interactive (or Synchronous) groupware is increasingly be - ing deployed in widely distributed environments. Users of such applications are accustomed to direct manipulation in- terfaces that require fast response time. The state that en- ables interaction among distributed users can be replicate d to provide acceptable response time in the presence of high communication latencies. We describe and evaluate design choices for protocols that maintain consistency of such sta te. In particular, we develop workloads which model user ac- tions, identify the metrics important from a user' s viewpoi nt, and do detailed simulations of a number of protocols to eval- uate how effective they are in meeting user requirements.