Study On The Spatial Data Sharing And Querying In WebGIS Based On GML

WebGIS is the production of Internet technology applying to GIS exploitation.GIS is being expanded with WWW,and is also being a general tool.But with the rapid development of WWW technology, WebGIS is facing of a new challenge for the further development.It is perfectly essential for WebGIS to explore a kind of new technology,which can resolve the opening problem of WebGIS.Spatial data sharing is the fundamentle of opening WebGIS.Nowadays,the apperance of eXtensible Markup Languages(XML) brings a new mechanism to store and transport information .XML will bring spatial data sharing to a new age on the Semantic Web that was raised by W3C recently . In this paper,the author deeply analyzes the technical characteristics and problems of today's WebGIS.The WebGIS with multi-tier architecture is improved with the new XML technology.The main works and contributions in the paper are as follow:â‘  Using the OGC's Geography Markup Language (GML) which is a geographic encoding specifiction based on XML ,combining the traditional B/S architechture,we provide a sptial data sharing model in WebGIS based on GML.The model stresses on the sharing at the tier of data ,and is expected to resolve the spatial data's tranport and exchange on net.â‘¡ Using GML to present the common geographic data model.Refering the specification and the requirement of spatial data management and nevigation,We design the GML sptial data exchangable format,and deeply describe the structure of the GML wrapper.Thus,the system would be a platform of spatial data sharing and management on the Internet.â‘¢ Study on the storage and management of shared spatial data based on RDBMS.â‘£ At the client side of the architechture,we provide the way of spatial querying based on client GML chache.This will resolve the client's poor query function and the dependent of the platform.With the design,we can query integrating data ,and improve the client's function.We provide the GQuery language based on XQuery to query multi-sources spatial data in GML format.At the end of this paper,we design the GML parser to support GML-query.