Research And Implementation Of Application Of Com To Gis Whole Structure

Geographic Information System(GIS) has had great progress in the past seveval decades, and is extending its application area constantly with the development of computer and network technology. Many places reqire and depend on GIS more and more,and this makes GIS software grow mature in function.At the same time,the scale and complication of GIS software grow rapidly.Traditional development patterns,by which most GIS softwares are developed,are not effective in dealing with large scale and high complication software.As a result ,most GIS softwares can not satisfy the requirements of modern software,and this prevents popularization of GIS .To resolve this problem brought about by system structure,we need to develop GIS by software itself. This paper researches the theory of applying Component Object Model(COM) to GIS platform, separates GIS into several components that have high cohesion and low coupling in whole strucure in consideration of logic and implementation. By this way, implements complete and real ComGIS. To organize these components in a more effective way,this paper gets nudge from computer network protocols and proposes a component-based layered system structure that is closer to human's natural thinking to reduce the difficulty of development and maintenance. In practice, a general GIS platform based on this layered system structure is designed and implemented, and an instance of using existing components to build WebGIS based on ActiveX is provided to embody the flexibility of this structure.