Resource rich laptops are becoming the primary computing platform of contemporary users. The ubiquity of high speed wireless networks allow these users to operate from a variety of locations: home, work and from a third place. In each of these locations, users encounter different kinds of local participants while still communicating with their global wireless partners. An empirical analysis of the wireless availability behavior of a large number of wireless users in a variety of communities showed a trend towards smaller user session lengths as well as longer durations between sessions with observable node churn. An analysis of various groupware systems using these wireless availability traces showed that prior systems would have performed poorly, especially during peak availability durations when many group members were simultaneously available.
Our analysis showed that maintaining a single shared copy is untenable for wireless workgroups. Instead, we propose a moderated group authoring system called flockfs. 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 document versions 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. These provenance records allows any users to independently decide whether their updates had been incorporated into the final version of a particular file. A prototype userspace file system implementation of flockfs exhibits acceptable file system performance and update propagation latency.
Surendar Chandra is currently an assistant Professor in the Computer Science and
Engineering department at the University of Notre Dame. His research interests
are directed towards operating system topics in multimedia, mobility, storage,
security, networks and sensor systems. He received his Ph.D. in Computer Science
from Duke University under the supervision of Carla Schlatter Ellis. He spent
2000-2002 as a faculty member at the University of Georgia. His work was
supported by Defense Intelligence Agency, HP, National Science Foundation and
Yamacraw. He is the recipient of an NSF CAREER award.