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The Research and Application of the Web Map Issuing Technology  Yan Huiwu Research Center for Environmental Engineering & Management Shenzhen Graduate School of Tsinghua University Shenzhen 518055 Email: yhwmcy@263.net  Wu Tao School of Resource & Environmental Science Wuhan University Wuhan 430079 Email: wt1118wc1118@263.net  Fei Lifan Nowadays, with the quick development of the technology of the computer and the communication, the world has entered into the era of the informational network. Just as the other traditional subjects, cartography also faces the tremendous impact of the informational network. Giving the users a quick and new approach of all kinds of the maps, the Internet makes the application of the maps a new definition and gives birth to new products of cartography — web maps: Web maps belong to a new kind of maps which are browsed, produced and used in the network. They use the Internet as the medium of transmission. They offer the users with continuous and multi-scaled description of space. They also offer the users with exact geographical coordinates and functions of spatial searching, query and analysis, whose key features are object-oriented, distributive and mutual operational. With the popularization of the Internet, web maps which serve the visualization and transmission of the spatial information will win more recognition by the people. To date, web maps have changed a lot in the system framework, and in the methods of creating and storing the map data. In order to be used commonly, easily and universally, more and more web maps are nowadays based on the method of the “thin client” in their creation. Through comparison and research of these web maps, the authors have discovered that they are not so ideal as far as the ease of creation, the convenience in updating of the cartographic data and the effectiveness of mutual operation to and from the users are concerned. In order to realize the effective organization of various kinds of web maps’ data with an easier way and to satisfy the basic needs of ordinary people for spatial information as much as possible, the authors have built and realized the real “thin client” of the web map issuing system, using the contemporary prevalent technology — the Flash technology, combined with the professional knowledge of the web maps and the data of the most advanced one hundred enterprises in Shenzhen City The analysis of today’s issuing technology for the web maps Nowadays, with the improvement of the network technology, the web maps have been developing continuously. They have changed a lot in the system framework, exploiting way and the way to deal with the cartographic data. As regard to their system structure, web maps have already been developed from the original C/S structure to present B/S structure. The way of their creation was based on the programming languages for the web page such as CGI(Common Gateway Interface)or JavaScript(a technology of dynamic web page programming)in the early stage. But at the present the object-oriented programming languages are being used just like Java and so on, which are based on the API programming. In the processing of the map data, the use of raster maps has been expanded to the use of the vector maps as well. Through the renovation of the crucial technologies mentioned above, the functions that web maps can realize are more powerful. The information that can be integrated is more abundant, and the operations for the users, easier. The web maps are being satisfying the needs of the users in various fields with their spatial information. Through the research of many current web maps issuing systems, the authors have found that these systems tend to be consistent in the aspect of the system framework and the creating method. The affairs that the server deals with are clearly departed from the things that the client does. Thereby it is beneficial for the web maps to become greater in size, more specialized and more integrated. However, this popular method of creating the issuing system for the web maps has some defects inevitably: the building of the system is difficult, which needs not only a lot of developers, but also much time. The cartographic data of the issuing system are embedded in API plotting functions instead of being managed by a database system. So it makes the updating of the cartographic data be tedious and complicated. When the bandwidth of the network is not large enough, the users have to wait for the results of their operations for so long a time that exceeds beyond their patience. The web maps are transmitted through the network, whose receivers should be the ordinary people who do not necessarily have the professional knowledge about the web maps. But the defects which we have just discussed make the issuing system of the web maps have a bottle-neck effect, namely, the information that the users receive is much less than the information that the server can supply. The ratio between the performance and the cost of this kind of systems is very low. So it is not beneficial to popularize the web maps for the ordinary people. According to the above mentioned analysis, we have to use different technologies of the web map issuing systems for different web map users. For the specialized users, we can continue the creating method of the web map issuing systems. But for the ordinary people, we should use a new method that utilizes the technologies as simply as possible, in order to promote the popularization of the web maps. The feasibility of realizing the web map issuing system using the Flash technology Flash is an animation designing software developed in June 1999 by an American company named MACROMEDIA. Its technological features are listed below:
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