Design And Impiementation Of The Distributed Virtual Experiment For E-Learning System

Some technologies about distributed system are studied in my paper, and parts of these technologies are applied to the system that I have built.Because the status of web is not very good currently, the time delay that is caused by web transmission hampers the development of distributed virtual experiment. Two methods of reducing the quantity of transmitting information in web are introduced in this paper. Firstly, when we solve the problem about consistency of space, the actions of virtual objects are compartmentalized to certain actions and uncertain actions. When a certain action is disposed, only start signal and the relevant function of the action are transmitted in web, and each client oneself simulates the course of this action locally. The relevant algorithm for this method is listed in this paper. Secondly, I intend to use the method of information filtering that based on multicast. Every client can select the useful information according to his own need, and the useless information will be filtrated. The first method has beenapplied to a simple system and has got a good result.About the question of consistency of time in distributed system, an algorithm that studied by Beijing University of Aeronautics and Astronautics is introduced. I also ameliorate this algorithm on the basis of requirement for distributed virtual experiment.After analysis of many methods for concurrent control and the requirement of my system, I adopt the method of pessimistic lock.In my paper, I also introduce the course of designing and implementing a distributed virtual experiment, including requirement analysis of system, design for function and structure, choice of tools. I list the questions that I have met in the course of achieving the system, and I also give the relevant methods to solve these questions.