Supporting activity-centric collaboration through peer-to-peer shared objects

We describe a new collaborative technology that is mid-way between the informality of email and the formality of shared workspaces. Email and other ad hoc collaboration systems are typically lightweight and flexible, but build up an unmanageable clutter of copied objects. At the other extreme, shared workspaces provide formal, structured collaboration, but are too heavyweight for users to set up. To bridge this gap between the ad hoc and formal, this paper introduces the notion of "object-centric sharing", where users collaborate in a lightweight manner but aggregate and organize different types of shared artifacts into semi-structured activities with dynamic membership, hierarchical object relationships, as well as real-time and asynchronous collaboration. We present a working prototype implemented with a replicated peer-to-peer architecture, which we describe in detail, and demonstrate its performance in synchronous and asynchronous modes.