A New Paradigm of User Intention Preservation in Realtime Collaborative Editing Systems

The concept of time and ordering of events are correlated key issues in distributed computing as well as computersupported collaborative work (CSCW) systems. This paper revisits some of the assumptions that have generally been made regarding time and event ordering in distributed systems and argues that they are no longer appropriate if the goal is to faithfully preserve user intentions in CSCW systems. In particular, the following contributions are made in the context of collaborative editing systems. First, we discuss how the user intentions might be impacted when the finite duration of drawing operations are considered. Secondly, we propose that total ordering of events should give the users the right of participation instead of being solely determined mechanically by the system. Thirdly, a new concept of active whiteboard is proposed which supports various integrity constraints on objects and object groups to maintain user intentions in a more sophisticated way. Additionally, for the sake of completeness, the problem of maintaining consistency in the face of unreliable and highlatency communication channels is also covered.