Moderated group authoring system for campus-wide wireless workgroups

This paper describes the design and implementation of a file system based distributed authoring mechanism for use among campus-wide wireless workgroups. We use long term wireless user availability traces from an university to evaluate prior groupware systems. We show that earlier systems would have performed poorly, especially during peak availability durations when many group members were simultaneously available. Our system, flockfs, addresses the poor performance by maintaining one updateable copy of the shared content on each group member’s node. It also hoards read-only copies of each of these updateable copies in any interested group member’s node. The various copies are reconciled using a moderation operation; each group member incorporates updates from all the other group members into their own copy. The various document versions eventually converge into a single version through successive moderation operations. The system assists with this convergence process by logging the provenance records of all causal reads of contents from other replicas. A user space file system prototype of flockfs exhibits acceptable file system performance. A subjective evaluation showed that moderation operation was intuitive to students who typically used emails for group authoring.