The Research And Realization Of P2PGIS Technology

The author gives a new way to solve the problem that WebGIS has a lower transportion efficiency with amount of data. By used P2P technology, it encourages all peers to take part in the data transportion service, which ask for data . Further more, the author proposes a new research direction of CSCW under the new GIS architecture by used the advantage of P2P technology in CSCW. It furthers the application depth of WebGIS. In order to distinguish from traditional WebGIS, the author gives a name P2PGIS of the WebGIS based on the P2P technology.The thesis first point out the feasibility and advantage of solving the WebGIS's existing problem by analyzing the P2P's born background, application characteristic and the difference between grid and P2P. Then, it detailedly describes the work flow and key algorithms of P2PGIS's data transportion. The key algorithms include improved [Plaxton 1997] route algorithm, NAT blaster algorithm based on TCP, piece selection algorithm and choking algorithm. These key algorithms not only solve the key problem-amount data with lower data transportion efficiency, but also make the P2PGIS application system have superiority than other P2P application system. Besides, the thesis proposed a conception model of P2PGIS CSCW by the characteristic of GIS and P2P. The conception model includes P2PGIS CSCW's cooperative mode, control mechanism, architecture and research content. It will further the depth and extent of GIS application domain.At last, the thesis introduces the method of developing the P2PGIS application system by using JXTA and ArcIMS. It gives the class realization of system's main function and realizes a demo system. By comparing the transportion speed of P2PGIS application system and WebGIS application system, the author conclude that as the numbers of peers increased, the public information ditribute system' transportion speed which developed by ArcIMS 9 directly declines rapidly while it obviously raises rapidly which developed in P2PGIS mode.Thereby, the thesis's originality is that it has introduced P2P technology into solving the the problem that WebGIS had a lower transportion efficiency with amount of data, and realized a demo system developed by JXTA and ArcIMS. As it turned out that the P2PGIS application system's integer performance has more advantage than the traditional WebGIS application system.