Coordination for Synchronous Cooperative Systems Based on Fuzzy Causal Relations
Synchronous cooperative systems (SCS) bring together users that are geographically distributed and connected through a network to carry out a task. Examples of SCS include Tele- Immersion and Tele-Conferences. In SCS, the coordination is the core of the system, and it has been defined as the act of managing interdependencies between activities performed to achieve a goal. Some of the main problems that SCS present deal with the management of constraints between simultaneous activities and the execution ordering of these activities. In order to resolve these problems, orderings based on Lamport-s happened-before relation have been used, namely, causal, Δ-causal, and causal-total orderings. They mainly differ in the degree of asynchronous execution allowed. One of the most important orderings is the causal order, which establishes that the events must be seen in the cause-effect order as they occur in the system. In this paper we show that for certain SCS (e.g. videoconferences, tele-immersion) where some degradation of the system is allowed, ensuring the causal order is still rigid, which can render negative affects to the system. In this paper, we illustrate how a more relaxed ordering, which we call Fuzzy Causal Order (FCO), is useful for such kind of systems by allowing a more asynchronous execution than the causal order. The benefit of the FCO is illustrated by applying it to a particular scenario of intermedia synchronization of an audio-conference system.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1085838Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1122
 T.W. Malone and K. Crowston, "The interdisciplinary study of coordination", ACM Computing Surveys, Vol. 26, No. 1, March 1994.
 A Coordination Component Framework for Open Systems Juan Carlos Cruz, Sander Tichelaar, Oscar Nierstrasz SCG Report, IAM, University of Bern,1996.
 Birman, A. Schiper, and P. Stephenson, "Lightweight Causal and Atomic Group Multicast," ACM Trans. Compt. Syst. Vol. 9, No. 3, ISSN:0734- 2071, Aug. 1991, pp 272-314.
 Roberto Baldoni and Ravi Prakash and Michel Raynal and Mukesh Singhal. "Efficient Ôû│-causal broadcasting". International Journal of Computer Systems Science and Engineering, Volume 13, Number 5, 1998, pp. 263-269.
 Leslie Lamport. "Time, Clocks, and the Ordering of Events in a Cooperative System". Communications ACM, Volume 21, Number 7, ISSN:0001-0782, July 1978 pp. 558-565.
 José Aguilar, "Dynamic Random Fuzzy Cognitive Maps". Computaci├│n y Sistemas, Abril-Junio 2004, Volumen 7, Numero 004, Instituto Politécnico Nacional, Distrito Federal, México, ISSN 1405-5546pp. 260- 271.
 S. Badaloni, M. Giacomin, "The algebra IAfuz: a framework for qualitative fuzzy temporal reasoning". Artificial Intelligence Volume 170, Number 10, Elsevier, July 2006, pp. 872-908.
 Yi Zhou, Tadeo Murata. "Modeling and Analysis of Distributed Multimedia Synchronization by Extended Fuzzy-Timing Petri Nets". Transactions of the Society for Desing and Process Science, Volume 5, Number 4, ISSN:1092-0617, December 2001, pp. 23-37.
 Ramaprabhu Janakiraman, Marcel Waldvogel and Lihao Xu. "Fuzzycast: Efficient Video-on-demand over Multicast". Proceedings INFOCOM 2002, New York, NY, USA, June 2002.
André L. V. Coelho, Alberto B. Raposo, Ivan L. M. Ricarte. "Bringing Flexibility to the Specification and Coordination of Temporal Dependencias among Multimedia Components". VII Simposio Brasileiro de Sistemas Multim├¡dia e Hiperm├¡dia, Florian├│polis, Brazil, SBC. 2001, pp. 37-52.
Luis Morales Rosales, Saul Pomares Hernandez, "A Temporal Synchronization Mechanism for Real-Time Distributed Continuous Media". International Conference on Signal Processing and Multimedia Applications (SIGMAP-06), Setubal, Portugal, Aug. 2006, INSTICC Press, ISBN 972-8865-64-3, pp. 302-309
Anna Haj Hac and Cindy X. Xue, "Synchronization in multimedia data retrieval". International Journal of Network Management, John Wiley & Sons, Inc. New York, NY, USA Volume 7, Issue 1 (January-February 1997), ISSN:1099-1190, pp. 33-62.
Eduardo Lopez, Jorge Estudillo, Jean Fanchon and Saul E. Pomares, "A fault-tolerant causal broadcast algorithm to be applied to unreliable networks". The 17th IASTED International Conference on Parallel and Distributed Computing and Systems (PDCS 2005), November 14-16.