Design And Implementation Of Web Based Virtual Geographic Fnvironment Prototype System Based On P2P

As the development of Network technology and Virtual Reality technology, with content being enriched of Virtual Geographic Environment, the research of Web based Virtual Geographic Environment System springs up. In most cases, the traditional Web based Virtual Geographic Environment System uses a centralized network architecture. All the data resources are placed on the server side, request from clients for data are always dependent on central server. With the increase of the amount of three dimentional data and growing number of users, and the security issues and other related issues raised up, central server is increasingly appeared to be inadequate.As a new network technology, and with its excellent network architecture, P2P technology continues to arouse people's attention. P2P has been used in distributed storage, collaborative work environment, computing and file sharing, application layer multicast, Internet indirection infrastructure, streaming media technology, search technology and other aspects. Applications based on P2P can be divided into three types by the standard of network architecture, including Centralized system, the Pure Distributed system, and Hybrid system. The network mode of P2P can make up limitation of the traditional one on several aspects, such as load balancing, real-time, reliability, scalability and security and so on.This paper designs Web based Virtual Geographic Environment Prototype System, PP-VGE, based on P2P technology by integrating three main areas of P2P, Virtual Geographic Environment and Web based one. In the aspect of organizing, management and rendering of three dimentional spatial data, this paper uses VRGIS for reference, including spatial index, thread pool, cache mechanism, LOD technique and technology of rendering, and so on, to ensure normal display of local data. In the realization of network layer module, it uses IOCP mode to build resource coordination server. A flooding algorithm is designed to prevent the failure situation of the resource coordination server, during network architecture transformation. This paper designs and implements details of file uploading, downloading and searching, and at last, practice proofs an ideal result.