| This thesis presents the design and implementation of a web-based geospatial data system that allows a user to query geographical information describing the world from a web browser. This geospatial data system (GSDS) provides information about political borders, rivers, lakes and islands in lakes for the entire world, and enables a user to create and submit a two-dimensional range query, and to list the query results.; A multi-tiered client-server architecture was used to implement GSDS. A Java Applet was used to design and build the user interface on the client side, and a Java Servlet was used to implement the server side program with two different architectures (fat client with thin server and thin client with fat server). CORBA was also used to implement the GSDS server, and the performance of the CORBA approach was compared with the Java Servlet approach. The comparison showed that the speed to run the CORBA server is approximately six times slower then that to run a Java Servlet.; More than 329 MB of shoreline, lake, island, political border and river data were used to show the geographic information of the whole world to a user. Significant preprocessing was done to split five vector files representing crude, low, intermediate, high and full resolutions into smaller data files. The range search was controlled such that data files within the user selected range were sized to minimize data transmission time yet still show reasonable geographical detail. An average transmission time of 12 seconds was achieved using the Java Servlet and two different query window tests. |
