Semantic Approaches to Structuring and Querying Web Sites

In order to pose eeective queries to Web sites, some form of site data model must be implicitly or explicitly shared by users. Many approaches try to compensate for the lack of such a common model by considering the hypertex-tual structure of Web sites; unfortunately, this structure has usually little to do with data semantics. In this paper a diierent technique is proposed that allows for both navigational and logical/conceptual description of Web sites. The data model is based on WG-log, a query language based on the graph-oriented database model of GOOD Gys94] and G-log Par95], which allows the description of data manipulation primitives via (sets of) graph(s). The WG-log description of a Web site schema is lexically based on standard hypermedia design languages, thus allowing for easy schema generation by current hypermedia authoring environments. The use of WG-log for queries allows graphic query construction with respect to both the navigational and the logical parts of schemata. Site schemata are managed by Schema Robots, which assist clients in the process of identiication and retrieval of a set of candidate schemata. On the basis of the set of candidate schemata, the client may then query individual Web sites; extensive data caching is used to avoid f looding resulting from an excessive number of candidates. A remote Query Manager process, running side by side with standard Web servers, manages query execution and handles the presentation of the results to the client. Our schema is particularly suited for Intranets, while allowing for a smooth migration of Internet Web sites as more and more of them are produced on the basis of hypermedia design and generation methodologies.