Modeling adaptable multimedia and self-modifying protocol execution

摘要

Over the years, researchers have tried to extend Petri net to model multimedia. The focus of the research flows from the synchronization of multimedia without user interactions (UIs), to interactions in distributed environments. The issues in concern are the flexibility and compactness of the model when applied to model a system under change. Most existing models lack the power to model a system under change during execution. Petri net extensions have been developed to facilitate UTs in distributed environments, however, they require sophisticated pre-planning to lay out detailed schedule changes. On the other hand, there has been active research on self-modifying protocols (SMPs) or adaptive protocols in recent years. Plenty of models have been developed to model communication protocol execution, to name a few, finite state machines, communicating finite state machines, Petri nets. However, there exist no suitable models to simulate protocols that are self-modifying or adaptive during execution. In this paper, we propose a Reconfigurable Petri net (RPN) for adaptable multimedia. A RPN comprises of a novel mechanism called modifier. This modifier can create a new change or delete an existing mechanism (e.g. arc, place, token, transition, etc.) of the net. In a way, modifier embraces controllability, reconfig-urability, and programmability into the Petri net, and enhances the real-time adaptive modeling power. This development allows a RPN to have a greater modeling power over other extended Petri nets. The paper includes both the model and theory required to establish the technique's validity. Examples are also shown how RPN can be used to model interactive multimedia, and simulate SMPs. A simulator has been developed using Visual C++ under Windows NT to show that RPN is feasible.