| As the World Wide Web is growing at a phenomenal rate, it becomes more and more difficult to retrieve information of interest from the enormous number of resources that are available. Currently, there are two ways to retrieve information from the Web, namely, navigation/browsing and searching by search engines. However, these search methods have significant limitations, such as, the "lost-in-hyperspace" phenomenon, the ignorance of the hypertext structure, etc. These drawbacks motivated the development of a flexible and powerful web query system.; This thesis presents a prototype system developed to query the Web with database query languages. In our prototype system, the Web is modeled as a labeled directed graph which can be stored in a relational database. A parser was designed and implemented in our prototype system to extract the information of a web page from the source HTML file and store it into the database. Three query facilities are developed in the prototype system, namely, the content query, the structure query and the advanced query, which can be used to pose queries on both the content and the hypertext structure of web pages. Extensive experiments have been performed to test the prototype system. The testing results show that database query languages can be used successfully in querying the Web. |
