Research And Development Of WebGIS Based On Client/Server

Geographic Information System (GIS) is able to support various functions such as spatial query, spatial analysis and attribute management. With the continuous advancement of Internet technology and increasing demands for GIS, integrating of GIS and network technology, publishing spatial data, providing spatial data display, query and analysis functions to users become the inevitable development trend to GIS. WebGIS is still in trial phase domestically although there are a few WebGIS products developed by foreign companies. Based on this situation, an independent copyright WebGIS software platform is developed in this paper.A complete WebGIS platform based on the TCP/IP is constructed for users by using C/S model, which accomplishes network access from client to server and achieves multiple functions. The method to design and implement the client is described, the unified data format (*. gis feature file and *. att attribute file) is defined, and the difficulties for the network communication caused by massive geographic data are solved to manage the geographic data by using vector format. The users complete operations of the geographic objects in the management information platform with functions of GIS. And the system achieves map display, map zoom, layer control, professional query, editing (deleting, adding, modifying) geographic data, downloading files and so on. Then the paper describes the method to design and implement the map file server, which can manage the client connection and update the remote map files in the client. Windows Socket is used for data communication between client and server. The establishment of communication protocol of the map operations between the client and server is defined in this paper, which is also the interpretation rule between data packets of sender and data packets of receiver.This paper accomplishes the programme design, communication function between the client and server, and implements basic functions of WebGIS, which detaches GIS from the shackles of information island.