Application And Research Of Grid In GIS

Grid computing is a new computation module which is specifically aimed at the complex scientific computation. It develops rapidly accompanied by the network and is considered as third-generation Internet. Grid computing takes full advantage of geographically distributed computational resources for the solution of large scale complex problems, especially for the problems that can't be solved relying on local resources only. This thesis deals with the application of grid computing in GIS. The main research work includes:Firstly, this thesis presents the characteristics of grid computing such as distributivity, self-similarity, etc. Then, it focuses on the Open Grid Services Architecture (OGSA) which is the most important grid architecture at present.Secondly, the architecture and main function of traditional GIS is given in the first place. Then it presents the technology of Grid GIS and Spatial Information Grid which is an important foundation of Grid GIS. After that, a model of four-story architecture of Grid GIS is constructed. Also, the main advantages of Grid GIS are enumerated.Thirdly, the architecture and the calling process of Web Service are presented. Making use of Toolkit4.0, diminutive grid composed of three computers is successfully constructed. The whole process is expounded, including preparations for installation of GT4, GT4 installation, the deployment of authentication system and security mechanism.Finally, Grid GIS system is constructed based on three computers, integrating Eclipse with GT4. Then two grid services are employed to the system for experiments. One is for composing map; another is for shortest path routing. In the above first grid service, it places three layers from the same map in three different computers. Then it handles separately those three layers on three computers, composes a map of those three layers and sends the map to the client. In the above second one, all data is also stored in three different computers. Through Geographic data processing, it obtains the shortest path between the two places given by the client and sends the result back to the client. At last the two services are tested with different experimental data. Compared with the ordinary GIS , the results show that running time is reduced in high degree under the grid on the premise of ensuring the validity of the grid service especially when there is a great deal of data.