Using the Floor Control Mechanism in Distributed Multimedia Presentation System zyxw Timothy K. Shih, Lawrence Y. Deng, I-Chun Liao, Chun-Hung Huang and Rong-Chi Chang Dept. of Computer Science and Information Engineering Tamkang University, Tamsui, Taipei Hsien, Taiwan 25 1 zyxwvut , R.O.C. zyxw E-mail:tshih@cs.tku.edu.tw Abstract zyxwvuts Establishing a web-based distributed multimedia presentation system environment is a technical challenge zyxwvutsrqpo .In this paper, we describe how to present different multimedia objects on a web presentation system with floor control mechanism as a result of the distance learning environment indispensably. The distributed approach is based on an extended timed Petri net model. Using characterization of extended time Petri net, we express the temporal behavior of multimedia objects; on the other hand, we introduce the concepts of user interaction. The main goal of our system is to provide a feasible method to represent a schedule and navigation of different multimedia objects with user interaction. zyxwvu In addition, users can dynamically modify and verify different kinds of conditions during the presentation. To verify the structural mechanism, we implement an algorithm using the Petri net diagram, analyzing the model by time schedule of multimedia objects, and produce a synchronous set of multimedia objects with respect to time duration. Specially, we consider the interactive facilities to support the distance-leaming requirement. We propose a floor control mechanism, which provides four types of control (free access, equal control, group discussion, and direct contact). These control mechanisms are sufSicient to the- use of distance learning environment. Keywords: Petri Net, Distributed Multimedia Presentation, Distance Learning, Floor Control 1. Introduction To control and demonstrate different types of multimedia objects is one of important functions in distributed multimedia presentation system. Unfortunately, we saw many “Black magic” compromised multimedia presentation systems; there is little theory to describe the methodologies of such compromised system. The concept of our model is based on the Petri net [l-31. Petri net is a graphical and mathematical modeling tool applicable to many systems. Its features can be used with both practice and theory. Thus, it provides a powerful medium of communication between them. Additional extensions have been proposed, and this has led to the following types of Petri nets: the timed Petri net, the stochastic Petri net, colored Petri net, and object-related Petri net.[6-121 The “Object Composition Petri Net”(0CPN) and the “extended Object Composition Petri Net”(X0PCN) were two graphic-based models that proposed synchronous theoretical for multimedia. The OCPN is a comprehensive model for specifying timing relations among multimedia data. The XOPCN can specify temporal relationships for the presentation of pre-orchestrated multimedia data, and to set up channels according to the required Qos of the data 14, 51. These two models lack methods to describe the details of synchronization across distributed platforms and do not deal with the schedule change caused by user interactions in interactive multimedia systems [ 131. However, when considering the network transport issue of multimedia and the floor control with multiple users, OCPN/XOPCN model are not sufficient to deal with those problem. In this paper, we use the extended timed Petri net to construct the web operations on a distance learning system. When multimedia objects are represented on the - 0-7695-1080-9/01 $10.00 zyxwvutsrq 0 2001 IEEE 337