A Research On WebGIS System Based On Web Service

As a conjunction of Internet technology and GIS technology, the development of WebGIS has closely related with the development of Computer technology. From 90s, as the network technology developed quickly, which presented by Internet, WebGIS applications have developed rapidly. Meanwhile, there also appeared many questions in WebGIS systems. Some of these questions are brought by Web software, such as the cross-platform and cross-language problems. Others are brought by GIS software, such as the data interoperative. So, we must do research in both GIS and Web areas to efficiently solve these problems. At present, there are two types of standardization organizations who try to solve those problems: the organizations who pay attention to Web, such as W3C, UDDI etc, and the organizations who pay attention to geographic information share and interoperability such as ISO TC211, OGC etc. All these two organizations present the concept of Web Service, but they are different. W3C pay more attention to the technology solutions and implementations, while OGC pay more attention to the concept of services, that is, OGC emphasis the status and function of geographic information services in Web Services. In another word, OGC emphasis the framework and concepts of Web Service, W3C emphasis the implementation and technology of Web Service. In this paper I first introduce the Web Service from W3C and OGC seperately, then expatiate the effect and significance of their protocols and standards to WebGIS.Base on the research about W3C and OGC standards, I present a conceptual model of WebGIS. In this model, I utilize Web Service stack as the core technology reference to the model architeture. Then based on this conceptual model, I present the sketch design and the WebGIS prototype. This WebGIS prototype includes three indepedant parts: Data Server, Application Server and Client. These three parts exchange messages to work together and accomplish user's command.Then, based on Visual Studio .Net development platform, I present the detail design and implementation procedure of this WebGIS prototype, which include the design and implementation of Data Server, Application Server and Client. The development of Data Server uses the from-bottom-to-top development mode. This development procedure include several steps: the development of the dynamic link library, the development of COM component based on Dynamic Link Library and the development of Web Services based on COM component. Because I use thin client application mode, so the implimentation of the client just includes two aspects: the interface design and the interaction with Application Server. In the implementation of the Application Server, I mainly use the Web Service provided by Data Server to provide the various functions to client. By these steps, Iimplement a 3 tier scalable WebGIS system by Web Service.Finally, I conclude the research and implementation of WebGIS system based on Web Service, and then present the problems that need to be solved father and the vista of Web Service.