Transparent Latecomer Support for Synchronous Groupware

  • Stephan Lukosch
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2806)


In a collaborative session users may join and leave. A user who joins a session is called a latecomer. A latecomer needs the current state of the collaborative session to participate in the session. There exist different approaches to accommodate a latecomer. The runtime system can, e.g., transfer the state to the latecomer or replay how the session state was reached. If the state is maintained on a well-known server, it is quite simple to supply the latecomer with the current state. However, if the server is not available, the latecomer cannot join. To increase the fault-tolerance, the runtime system has to use a decentralized approach. In this case, race conditions must be taken into account. DreamObjects is a platform that simplifies the development of shared data objects. It supports a direct state transfer as well as a replay and lets a latecomer choose how to join a session. Both approaches are completely integrated in the runtime system, work completely decentralized, and do not block the other participants in their current work.


Method Call Distribution Scheme Shared State Initial Supporter Runtime System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Anupam, V., Bajaj, C.L.: Shastra: Multimedia Collaborative Design Environment. IEEE Multimedia 1(2), 39–49 (1994)CrossRefGoogle Scholar
  2. 2.
    Chabert, A., Grossman, E., Jackson, L., Pietrovicz, S., Seguin, C.: Java Object-Sharing in Habanero. Communications of the ACM 41(6), 69–76 (1998)CrossRefGoogle Scholar
  3. 3.
    Chung, G., Dewan, P., Rajaram, S.: Generic and Composable Latecomer Accomodation Service for Centralized Shared Systems. In: Chatty, S., Dewan, P. (eds.) IFIP Working Conference on Engineering for HCI, Heraklion, Crete, Greece, pp. 129–145. Kluwer Academic Publisher, Dordrecht (1998)Google Scholar
  4. 4.
    Keith Edwards, W.: Flexible Conflict Detection and Management In Collaborative Applications. In: Proceedings of the 10th annual ACM symposium on User interface software and technology, Banff, Alberta, Canada, October 1997, pp. 139–148 (1997)Google Scholar
  5. 5.
    Greenberg, S., Roseman, M.: Using a Room Metaphor to Ease Transitions in Groupware. Technical Report 98/611/02, Department of Computer Science, University of Calgary, Calgary, Alberta, Kanada (January 1998)Google Scholar
  6. 6.
    Greenberg, S., Roseman, M.: Groupware Toolkits for Synchronous Work. In: Beaudouin-Lafon, M. (ed.) Computer-Supported Cooperative Work (Trends in Software 7). ch. 6, pp. 135–168. John Wiley & Sons Ltd., Chichester (1999)Google Scholar
  7. 7.
    Lamport, L.: Time, Clocks, and the Ordering of Events in a Distributed System. Communications of the ACM 21(7) (July 1978)Google Scholar
  8. 8.
    Lauwers, J.C., Lantz, K.A.: Collaboration awareness in support of collaboration transparency: requirements for the next generation of shared window systems. In: CHI 1990 Conference on Human Factors in Computing Systems, Special Issue of the SIGCHI Bulletin, Seattle, Washington, USA, April 1990, pp. 303–311 (1990)Google Scholar
  9. 9.
    Lukosch, S.: Adaptive and transparent data distribution support for synchronous groupware. In: Haake, J.M., Pino, J.A. (eds.) CRIWG 2002. LNCS, vol. 2440, pp. 255–274. Springer, Heidelberg (2002)CrossRefGoogle Scholar
  10. 10.
    Lukosch, S., Roth, J.: Reusing Single-user Applications to Create Multi-user Internet Applications. In: Böhme, T., Unger, H. (eds.) IICS 2001. LNCS, vol. 2060, pp. 79–90. Springer, Heidelberg (2001)CrossRefGoogle Scholar
  11. 11.
    Lukosch, S., Roth, J., Unger, C.: Marrying On-Campus Teaching to Distance Teaching. In: Proceedings of the 19th World Conference on Open Learning and Distance Education, Vienna, Austria (June 1999)Google Scholar
  12. 12.
    Lukosch, S., Unger, C.: Flexible Management of Shared Groupware Objects. In: Proceedings of the Second International Network Conference (INC 2000), July 2000, pp. 209–219. University of Plymouth, United Kingdom (2000)Google Scholar
  13. 13.
    Manohar, N.R., Prakash, A.: The Session Capture and Replay Paradigm for Asynchronous Collaboration. In: Proceedings of the Fourth European Conference on Computer Supported Cooperative Work, pp. 149–164, Stockholm, Sweden (September 1995)Google Scholar
  14. 14.
    Mauve, M.: Distributed Interactive Media. PhD thesis, Universität Mannheim (2000)Google Scholar
  15. 15.
    Mills, D.L.: Network Time Protocol (Version 3) Specification, Implementation and Analysis. Request for Comments 1350, IETF (March 1992)Google Scholar
  16. 16.
    Prakash, A., Shim, H.S., Lee, J.H.: Data Management Issues and Trade-Offs in CSCW Systems. IEEE Transactions on Knowledge and Data Engineering 11(1), 213–227 (1999)CrossRefGoogle Scholar
  17. 17.
    Roseman, M., Greenberg, S.: Building Real-Time Groupware with Group-Kit, A Groupware Toolkit. ACM Transactions on Computer-Human Interaction 3(1), 66–106 (1996)CrossRefGoogle Scholar
  18. 18.
    Roth, J.: ’DreamTeam’: A Platform for Synchronous Collaborative Applications. AI & Society 14(1), 98–119 (2000)CrossRefGoogle Scholar
  19. 19.
    Roth, J., Unger, C.: Group Rendezvous in a Synchronous, Collaborative Environment. In: 11. ITG/VDE Fachtagung, Kommunikation in Verteilten Systemen (KiVS 1999) (March 1999)Google Scholar
  20. 20.
    Schulzrinne, H., Casner, S., Frederick, R., Jacobsen, V.: RTP: A Transport Protocol for Real-Time Applications. Request for Comments 1889, IETF (January 1996)Google Scholar
  21. 21.
    Shim, H.S., Hall, R.W., Prakash, A., Jahanian, F.: Providing Flexible Services for Managing Shared State in Collaborative Systems. In: Proceedings of the Fifth European Conference on Computer Supported Cooperative Work, Lancaster, United Kingdom, pp. 237–252 (1997)Google Scholar
  22. 22.
    Vogel, J., Mauve, M.: Consistency Control for Distributed Interactive Media. In: Proceedings of the 9th ACM Multimedia, Ottawa, Canada (2001)Google Scholar
  23. 23.
    Vogel, J., Mauve, M., Geyer, W., Hilt, V., Kuhmünch, C.: A Generic Late Join Service for Distributed Interactive Media. In: Proceedings of the 8th ACM Multimedia, ACM MM 2000, Los Angeles, CA, USA, pp. 259–268 (2000)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Stephan Lukosch
    • 1
  1. 1.Computer Science II – Cooperative SystemsUniversity of HagenHagenGermany

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