The Research And Application Of WebGIS As A Component System

Geographic Information System is a science that connects tightly with computer technology. With the development of component-based software, components begin to be used in GIS domain. Now, the maturity of distributed object technology lets component become an important tool in WegGIS construction. Component technology solves the problems that traditional GIS faced in the past, such as long-period development and difficulties in system integration. It not only simplifies the development of GIS application system, but also provides the efficient and powerful developing method for WebGIS.At present, GIS software providers supply many tools for the construction of WebGIS application systems. ESRI's ArcIMS is one that used widely in them. However, when people use Java to realize their ArcIMS application systems, they should make their systems built up directly on ArcXML, a communicating language used in ArcIMS, which complicates the process of GIS system's implementation and forces developers to face the same problems traditional GIS faced.In this thesis, the author at first analyses the Component GIS and the tide of realizing WebGIS as a component system, then discusses the difficulties those programmers meet when using ArcXML directly. After clarifying the advantages of shielding ArcXML and packing GIS general functions, the thesis makes the decision of developing ArcIMS general components to attain the aim of simplifying the developing process of ArcIMS application system and shortening developing period.The primary work of thesis is listed in the following:(1) Analyze the actuality of GIS. From the opinion of GIS developing pattern, the thesis points out that realizing WebGIS as a component system is the certain result of GIS development and discusses it particularly.(2) Discuss the problems that will meet in period of using ArcXML directly in GIS functions' development and bring out the solution of using ArcIMS general components shield ArcXML. After the detailed study of ArcXML, the thesis presents the exact component design.(3) Use EJB component to implement an archetype system, which can provide the function of displaying maps and operating map layers.