| With the development of computer technology and Internet, the way to describe and analyze geospatial information of geographic information systems (GIS) has taken great changes. And many GIS network production emerged. GIS gradually from a centralized host for stand-alone single-user GIS, Desktop GIS development-based C/S and B/S application model of distributed GIS, geographic information available on the Internet and realize the sharing of geographic information resources.Geospatial data needs to be widely shared, exchanged and used, and geospatial data storage and processing environment be changed from the traditional centralized to distributed. "distributed" means that data and programs spread across multiple servers. And it is also a theoretical computing model for the study of geospatial data and processing which are network-dispersed. Distributed computing is conducive to the distribution and optimization conducted by geospatial data processing tasks in a competitive computer system, and it also could be used for dealing with the problems which are made by centrally hosted. The traditional problems are the bottleneck of resource, constraints and response deficiencies. Obviously, distributed environment has taken place of the traditional centralized environment, and become the main trend of geospatial data management and processing.In the distributed computing technology, Peer-to-Peer (P2P) computing technology has the unparalleled advantage. P2P break the traditional Client/Server mode, each peer in the network are equal, i.e. each peer not only provides services to other peers acts as a server, but also enjoy the services provided by other peers. non-centralized architecture with P2P technology not only eliminated single points of failure and scalability bottlenecks and other limition, improve the system robost, availability. Thus, It has great potential and development prospects to use P2P technology in Web service application, which faces the instability of network links and dynamic, heterogeneous.To combine the advantages of P2P and Web services, in order to achieve stability, robustness of sharing of geospatial information services and applications, it is proposed of geospatial data organization based on P2P and Web services.In this paper, we take P2P and Web services technology as foundation, analysize the key problem of geospatial information service, such as stability, availability, single point of failure and access bottleneck; archive the dynamic loading,route and search of geographic information services peers. And put forward the compare system and the completely research result, and enrich the framework of application technology in geosaptial information services with P2P.In this paper, we focused on the geospatial information services based on P2P. Mainly includes the theory and technology fundation of geospatial information services based on P2P, bulid the P2P overlay network, the logical framework of geospatial information services based on P2P, and deeply research the route, search algorithm P2P overlay network peers. Finally, verified the research problem with a prototype system.Details are as follows:1) Following the basic concept, this paper analyzed and compared the advantages and disadvantages of P2P and geographic information services, and find combination points, designed a logical framework of geographic information service system based on P2P.2) discussed registration and find of geographic information services; P2P Overlay network peer routing, dynamic peer algorithm, P2P search algorithms, and designed Hierarchical Hybrid P2P Network based on SuperPeer and put forward the algorithm on peer join, exit, resouce publish and locate, and analyzeed the influenceing factors of the performance of the algorithm.3) designed a prototype system of geospatial information services based on P2P, analyzed the combination method of P2P and geospatial information services with JXTA-SOAP. and illustrated in the prototype system. |
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