WebGIS is the production of Internet technology applying to GIS. WebGIS is a good tool to get GIS data and Geographic information service for us. But WebGIS meets some problems for the further development, such as absence of interaction and limitation of visiting heterogeneous database. So WebGIS needs some new technologies to resolve these problems. XML is a new technology, which promotes the development of Web. Geography Markup Language (GML) specification is defined by OGC. This specification is intended...