The Design And Development Of WebGIS Based On Ajax

With the Development of the Internet, more and more tabletop applications switch to the Web platform. In the GIS domain, the combination of Internet technology and GIS has caused the emergence of WebGIS. WebGIS changed the way of geo-spatial data acquisition, transmission, sharing and application, and it will be the direction of future GIS development. With the technical development, the WebGIS are used in more and more fields, and more and more new techniques also appeared. Google Maps based Ajax provides a new WebGIS design pattern. Ajax could meet the WebGIS requirement, such as the large number of immediate interaction, the frequent communication to servers and the data transmission requirements. It could also effectively reduce the burden on the server and the amount of data transmission. The client does not need to download any plug-ins. Ajax overcomes many problems of the traditional Web application, such as the white screen waiting phenomenon. Therefore, when a large number of online map services, such as Google Maps, appeared, Ajax has become the main way of building WebGIS.The Maplnfo map of Wuhan was used to form An Ajax based WebGIS platform using Web Service and ASP.NET AJAX as the Ajax frame. Through this research, a solution of establishing a WebGIS using Ajax was obtained, the principle and architecture of this pattern was proposed, demonstration of some of the functions were given. In the research, ASP.NET AJAX was used to develop client function. Because it has made a massive seals to JavaScript, and only one set of codes is needed to different browsers, the compatibility problem between different browsers was greatly improved. Simultaneously, ASP.NET AJAX was based on ASP.NET 2.0, so the functions of ASP.NET 2.0 can be used expediently. ASP. NET 2.0 was used to create the Web Service to provide data for the client-side, in order that data and the user interface can be separated. Some other techniques were also used in this study. For example, MapXtreme 2005 was used in the map-server development to enhance the GIS functions. VML and SVG was used in the client development to realize the client's line drawing functions...