Universidade Federal do Rio de Janeiro
Projeto de Cooperação Internacional CAPES/COFECUB
Grupo de Teleinformática e Automação


From multimedia models to multimedia protocols

Prof. Michel Diaz - LAAS-CNRS

13 de julho de 1998 - Sala H312 - 9:00 / 12:00 h, 13:30 / 16:30 h

Michel Diaz is Directeur de Recherche at the Centre National de la Recherche Scientifique (CNRS) and leads the Research Group ``Communications Software'' at the LAAS du CNRS, Toulouse. In 1989 and 1990, he spent a year as a visiting professor and staff at the University of Delaware at Newark and the University of California at Berkeley. He is been working on the development of methodologies, techniques and tools for the design of high speed multimedia cooperative distributed systems. He has written one book, more than 120 technical publications and is the editor of a North Holland volume on Protocol Specification, Testing and Verification, 1985, co-editor of three North Holland volumes on developing and using Formal Description Techniques for the Specification, Testing, Verification and Implementation of Protocols (on Estelle, LOTOS and the FORTE conference), co-editor of a LNCS volume on ``Application and Theory of Petri nets'', 1995, and co-editor of a World Scientific volume on Multimedia Modeling, 1996.


This talk presents a new general architecture and a new transport layer for multimedia systems. It will show how this architecture has been deduced from a formal model of the synchronization requirements inherent to multimedia objects. The global design methodology follows a three step process. The purpose of the first step was to well understand what multimedia requirements are; this has been done by defining general formal models of multimedia objects. Then a deep analysis of the present protocols was conducted and an extension of them was proposed in coherence with these models. The last phase led to the general multimedia architecture that has been designed to minimize the network and end-system communications resources, the end-to-end delay, and to fulfill the multimedia temporal requirements. This new architecture includes a new communication transport layer to transfer complex multimedia objects. This new transport protocol, based on the concept of Partial Order Connection, is a partially reliable and partially order ed protocol. The resulting protocol leads to the definition of a new, generic and application-dep endent service and to a set of related protocols that will be shown to be able to integrate the different flows and media. The proposed new connection, is a direct extension of the usual concepts of connection used in existing connection oriented -CO- (e.g. TCP) and connectionless -CL- (e.g. UDP) protocols. These ideas were implemented in the context of a generic teleconferencing system and the related general architecture will finally be discussed.