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Studies on the Key Technology of Spatial Data Sharing on the Internet
3 System Basic Structure
Based on the system design objective and present information sharing status in China, this system adopts the principle of both centralizing and distributed. Some information is shared in network center, others are shared to serve for public on sub-center, among those the network center is the core of this system, which is made up of three servers, including Web Server, data server and GIS server. 3.1 Web Server Web Server is the information exchange center between users and application server, it is in charge of receiving user request, returning part information, or hand out this request to those application procedure running at background, it also is in charge of returning the running result as proper form to explorer at HTML/HTTP standard.  Figure 2 The basic structure of system 3.2 Database Server Database Server is used to manage those sharing database in this system, it can supply needed data for application server and database server. 3.3 Application Srver Application Server is made up of advanced server which has the ability of fast processing, it also is equipped with the software such as ESRI ArcINFO?Mapobjects and some spatial data processing and analysis software. Application server is the core of this system, it organizes, analyzes and manages those data and information in database and response with the request from users. 3.4 Network Structure This system is a distributed network. It is made up of network center and sub-center in Beijing, Tianjing and Nanjin, all these are connected through Internet. These nodes also connect with CERNET, CSTNET, CHINAGBN and CHINANET. Yet by logic it is a virtual network on the Internet, all database in network center and sub-center are connected, forming an integer, serving for public as a whole. |