Flockfs, a moderated group authoring system for wireless workgroups

Abstract

This paper describes the design and implementation of a group authoring system for wireless users. Our analysis of the behavior of various groupware systems using wireless user availability traces showed that prior systems would have performed poorly, especially during peak availability durations when many group members were simultaneously available. These results motivate our design choices. flockfs maintains 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 manually incorporates updates from all the other group members into their own copy. The various document versions will eventually converge into a single version through successive moderations. The system assists with this process by automatically logging the provenance of all causal reads of contents from other replicas into the author versions. A prototype userspace file system implementation of flockfs exhibits acceptable file system performance and update propagation latency.