Looking Through The Technology Of WebGIS's Release Through ArcIMS

CIS(Geographic Information System) derived from 1950s. After developed for 4, 50 years, along with the boom of the computer science and the wide usage of Internet, GIS came to the Internet platform step by step. But, because domestic GIS started up later, not only the development platform are far behind the foreign ones, but also we can't use the foreign development platforms well. This article compares the two modes of release provide by the most popular WebGIS development platform, ArcIMS, refers plenty of English materials, in order to help the domestic WebGIS developer comprehend this software better. At last, the article will give some advices for the WebGIS development and predict the orientation of WebGIS's progress audaciously.There are two modes of WebGIS's release: dynamic mode and active mode, also usually called thin-client and fat-client separately. In the former mode, the server does almost all the works. The client only need to send request to and accept response from the server, of course, it needs to write request and process the response by itself. While the server needs to deal with the request sent by client and then send response back after a series of complicated operation. The latter mode uses the distributed-object, which let almost all works are done by the client and the only usage of server is to initialize the viewer. ArcIMS uses the two modes, called Html Viewer and Java Viewer by its own name. Depending on the unique structure of server of ArcIMS, this two viewer provide similar functions by very different principles.Now, the number of the domestic companies, which use ArcIMS to do development, is not small, in fact, because the technology is very new, the companies are almost starting to use it. The author ever came to two companies, both of which had no experience about it. They never compared these two modes,only used one mode random which they didn' t comprehend well yet. In the other hand, the development of domestic WebGIS platform walks along the steps of the foreign platforms so that we will never exceed the foreigners.This article compares the two modes all the sides including basic principle, files organization, procedure of logging in, principles of functions, functions and data management, lets the developers comprehend it more clearly, and then, draws conclusions in the fields of allocations, security, performance, functions and expansion ability, gives some advices about WebGIS development, at last, predicts the orientation of WebGIS's progress audaciously according to the characteristics of the technology and the progress of hardware, also gives some advice to the development of domestic WebGIS platform.