Research On Load Balancing Of Application Server On Distributed GIS

With the rapid development of the technology of computer and network, Internet has been used widely in each field of society. GIS has been used in many fields and developing rapidly. GIS of the single computer has been already unable to satisfy the demands for information distributing and resource sharing in the age of information as in the past. More and more people hope to interview and obtain spatial information by Internet, which desires high demand of development in GIS and impels it to transfer from centralized and isolated system to distributed and shared system. Distributed GIS becomes one of inevitable developing directors of GIS. Because of increasing of spatial information quantities and people's demands, the burden of GIS application server becomes heavier, and single server can not satisfy demands of great computing and parallel visit of many users. It must adopt the way of cooperation of multi computers to provide spatial information services. So, the problem of distributed GIS which needs to be solved imminently is how to assign tasks reasonably among multi servers to make servers stability and improve service ability of distributed GIS.In order to solve above-mentioned problems, the paper is based on analyzing and summarizing of distributed GIS and load-balancing technology, and has put forward the reasonable load balancing algorithm of distributed GIS. It has also studied and discussed the key points of design and realization of distributed GIS load balancing. The main contents of this paper include two parts:1. Research reasonable load balancing algorithm of distributed GIS.On the basis of analysis and summarizing of distributed GIS and load balancing, the paper has put forward a reasonable load balancing algorithm of distributed GIS according to the characteristic of distributed GIS application server and the policy and method realizing dynamic load balancing. It has discussed deeply the key points of this algorithm, including choosing of load balancing factors, making of load balancing threshold, location policy and work process of the algorithm.2. Research on the system architecture of distributed GIS based on the load balancing middleware and the design and realization of distributed GIS load balancing application server.On the basis of J2EE system architecture of distributed GIS, the paper has researched the distributed GIS architecture which based on the load balancing middleware according to the load balancing algorithm, has designed a load balancing application server and has analyzed the running mechanism and many key points of this server. Finally, the paper hasrealized a prototype system and has analyzed the experiment and test result.In conclusion, the load balancing of GIS application server is important research contents of distributed GIS. Using load balancing mechanism, multi application servers can cooperate in the distributed GIS to realize task scheduling and load assigning. And in this way it improves the service ability of the distributed system.