Issue No.06 - June (2012 vol.11)
pp: 1007-1020
Surendar Chandra , FX Palo Alto Laboratory, Palo Alto
This paper describes the design and implementation of a file system-based distributed authoring system for campus-wide workgroups. We focus on documents for which changes by different group members are harder to automatically reconcile into a single version. Prior approaches relied on using group-aware editors. Others built collaborative middleware that allowed the group members to use traditional authoring tools. These approaches relied on an ability to automatically detect conflicting updates. They also operated on specific document types. Instead, our system relies on users to moderate and reconcile updates by other group members. Our file system-based approach also allows group members to modify any document type. We maintain one updateable copy of the shared content on each group member's node. We also hoard read-only copies of each of these updateable copies in any interested group member's node. All these copies are propagated to other group members at a rate that is solely dictated by the wireless user availability. The various copies are reconciled using the moderation operation; each group member manually 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 using the made-with knowledge of all causal file system reads of contents from other replicas. An analysis using a long-term wireless user availability traces from a university shows the strength of our asynchronous and distributed update propagation mechanism. Our user space file system prototype exhibits acceptable file system performance. A subjective evaluation showed that the moderation operation was intuitive for students.
Collaborative editing of complex documents, moderated manual reconciliation, collaborative file system.
Surendar Chandra, "Moderated Group Authoring System for Campus-Wide Workgroups", IEEE Transactions on Mobile Computing, vol.11, no. 6, pp. 1007-1020, June 2012, doi:10.1109/TMC.2011.114
[1] T. Henderson, D. Kotz, and I. Abyzov, “The Changing Usage of a Mature Campus-Wide Wireless Network,” Proc. ACM MobiCom, pp. 187-201, 2004.
[2] R.M. Baecker, D. Nastos, I.R. Posner, and K.L. Mawby, “The User-Centered Iterative Design of Collaborative Writing Software,” Proc. Conf. Human Factors in Computing Systems (CHI '93), pp. 399-405, 1993.
[3] C.M. Neuwirth, D.S. Kaufer, R. Chandhok, and J.H. Morris, “Computer Support for Distributed Collaborative Writing: Defining Parameters of Interaction,” Proc. ACM Conf. Computer Supported Cooperative Work (CSCW '94), pp. 145-152, 1994.
[4] V. Bellotti, N. Ducheneaut, M. Howard, I. Smith, and R.E. Grinter, “Quality versus Quantity: E-Mail-Centric Task Management and Its Relation with Overload,” Human-Computer Interaction, vol. 20, pp. 89-138, June 2005.
[5] C.C. Marshall, “From Writing and Analysis to the Repository: Taking the Scholars' Perspective on Scholarly Archiving,” Proc. ACM/IEEE-CS Joint Conf. Digital Libraries (JCDL '08), pp. 251-260, 2008.
[6] L. Novik, I. Hudis, D.B. Terry, S. Anand, V. Jhaveri, A. Shah, and Y. Wu, “Peer-to-Peer Replication in WinFS,” Technical Report MSR-TR-2006-78, MSR, June 2006.
[7] A. Rajgarhia and A. Gehani, “Performance and Extension of User Space File Systems,” Proc. 25th ACM Symp. Applied Computing (SAC), Mar. 2010.
[8] K.P. Puttaswamy, C.C. Marshall, V. Ramasubramanian, P. Stuedi, D.B. Terry, and T. Wobber, “Docx2Go: Collaborative Editing of Fidelity Reduced Documents on Mobile Devices,” Proc. ACM MobiSys, pp. 345-356, 2010.
[9] J.H. Morris, M. Satyanarayanan, M.H. Conner, J.H. Howard, D.S. Rosenthal, and F.D. Smith, “Andrew: A Distributed Personal Computing Environment,” Comm. ACM, vol. 29, no. 3, pp. 184-201, 1986.
[10] S. Shepler, B. Callaghan, D. Robinson, R. Thurlow, C. Beame, M. Eisler, and D. Noveck, “Network File System (NFS) Version 4 Protocol,” IETF RFC 3530, Apr. 2003.
[11] V. Ramasubramanian, T.L. Rodeheffer, D.B. Terry, M. Walraed-Sullivan, T. Wobber, C.C. Marshall, and A. Vahdat, “Cimbiosys: A Platform for Content-Based Partial Replication,” Proc. Sixth USENIX Symp. Networked Systems Design and Implementation, pp. 261-276, 2009.
[12] P. Reiher, J.S. Heidemann, D. Ratner, G. Skinner, and G.J. Popek, “Resolving File Conflicts in the Ficus File System,” Proc. USENIX Technical Conf. USENIX Summer, pp. 183-195, http://www.isi. edu/johnh/PAPERSReiher94a.html , June 1994.
[13] P. Kumar and M. Satyanarayanan, “Flexible and Safe Resolution of File Conflicts,” Proc. USENIX Technical Conf., 1995.
[14] A. Demers, K. Petersen, M.J. Spreitzer, D. Terry, M. Theimer, and B. Welch, “The Bayou Architecture: Support for Data Sharing among Mobile Users,” Proc. Workshop Mobile Computing Systems and Applications, pp. 2-7, Dec. 1994.
[15] J.H. Howard, “Using Reconciliation to Share Files between Occasionally Connected Computers,” Proc. Fourth Workshop Workstation Operating Systems, pp. 56-60, Oct. 1993.
[16] M. Satyanarayanan, J.J. Kistler, P. Kumar, M.E. Okasaki, E.H. Siegel, and D.C. Steere, “Coda: A Highly Available File System for a Distributed Workstation Environment,” IEEE Trans. Computers, vol. 39, no. 4, pp. 447-459, Apr. 1990.
[17] T.W. Page, R.G. Guy, J.S. Heidemann, D. Ratner, P. Reiher, A. Goel, G.H. Kuenning, and G.J. Popek, “Perspectives on Optimistically Replicated Peer-to-Peer Filing,” Software—Practice and Experience, vol. 28, no. 2, pp. 155-180, johnh/PAPERSPage98a.html , Feb. 1998.
[18] C.A. Ellis and S.J. Gibbs, “Concurrency Control in Groupware Systems,” ACM SIGMOD Record, vol. 18, no. 2, pp. 399-407, 1989.
[19] B. Nowicki, “NFS: Network File System Protocol Specification,” IETF RFC 1094, Mar. 1989.
[20] J.J. Kistler and M. Satyanarayanan, “Disconnected Operation in the Coda File System,” ACM Trans. Computer Systems, vol. 10, no. 1, pp. 3-25, Feb. 1992.
[21] W.J. Bolosky, J.R. Douceur, D. Ely, and M. Theimer, “Feasibility of a Serverless Distributed File System Deployed on an Existing Set of Desktop pcs,” Proc. ACM SIGMETRICS Performance Evaluation Rev., vol. 28, pp. 34-43, 2000.
[22] X. Yu and S. Chandra, “Campus-Wide Asynchronous Lecture Distribution Using Wireless Laptops,” Proc. ACM/SPIE Conf. Multimedia Computing and Networking (MMCN '08), vol. 6818, pp. 68180M-1-68180M-8, Jan. 2008.
[23] S. Chandra and X. Yu, “An Empirical Analysis of Serendipitous Media Sharing among Campus-Wide Wireless Users,” ACM Trans. Multimedia Computing, Comm. and Applications (ACM TOMCCAP), vol. 7, no. 1, pp. 1-23, Jan. 2011.
[24] D. Tang and M. Baker, “Analysis of a Local-Area Wireless Network,” Proc. ACM MobiCom, pp. 1-10, 2000.
[25] D. Kotz and K. Essien, “Analysis of a Campus-Wide Wireless Network,” Proc. ACM MobiCom, pp. 107-118, 2002.
[26] M. Balazinska and P. Castro, “Characterizing Mobility and Network Usage in a Corporate Wireless Local-Area Network,” Proc. ACM MobiSys, pp. 303-316, 2003.
[27] D. Tang and M. Baker, “Analysis of a Metropolitan-Area Wireless Network,” Wireless Networks, vol. 8, nos. 2/3, pp. 107-120, 2002.
[28] A. Demers, D. Greene, C. Hauser, W. Irish, J. Larson, S. Shenker, H. Sturgis, D. Swinehart, and D. Terry, “Epidemic Algorithms for Replicated Database Maintenance,” Proc. Sixth Ann. ACM Symp. Principles of Distributed Computing (PODC), pp. 1-12, Aug. 1987.
[29] X. Yu and S. Chandra, “Designing an Asynchronous Group Communication Middleware for Wireless Users,” Proc. 12th ACM Int'l Conf. Modeling, Analysis and Simulation of Wireless and Mobile Systems (MSWiM '09), pp. 274-279, 2009.
[30] D.B. Terry, A.J. Demers, K. Petersen, M.J. Spreitzer, M.M. Theimer, and B.B. Welch, “Session Guarantees for Weakly Consistent Replicated Data,” Proc. Third Int'l Conf. Parallel and Distributed Information Systems, pp. 140-150, 1994.
[31] K.-K. Muniswamy-Reddy, D.A. Holland, U. Braun, and M. Seltzer, “Provenance-Aware Storage Systems,” Proc. USENIX Ann. Technical Conf., 2006.
[32] K.-K. Muniswamy-Reddy and D.A. Holland, “Causality-Based Versioning,” ACM Trans. Storage, vol. 5, pp. 13:1-13:28, Dec. 2009.
[33] A. Gehani and U. Lindqvist, “Bonsai: Balanced Lineage Authentication,” Proc. IEEE Ann. Computer Security Application Conf. (ACSAC), pp. 363-373, Dec. 2007.
[34] R.B. Segal and J.O. Kephart, “MailCat: An Intelligent Assistant for Organizing E-Mail,” Proc. Third Ann. Conf. Autonomous Agents (AGENTS '99), pp. 276-282, 1999.
[35] R. Boardman and M.A. Sasse, “‘Stuff Goes into the Computer and Doesn't Come Out’: A Cross-Tool Study of Personal Information Management,” Proc. SIGCHI Conf. Human Factors in Computing Systems (CHI '04), pp. 583-590, 2004.