Structuring and Querying the Web throughGraph - Oriented

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 hypertextual 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 data model description of Web sites, while allowing for graphical queries. The data model is based on WG-log, a description and query language based on the graph-oriented object database model of GOOD Gys94] and G-log Par95] allowing description of data manipulation primitives via graph transformations. WG-log description of the navigational part 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 navigational and data model parts of schemas. Site schemas are managed by Schema Robots, which assist clients in the process of identiication and retrieval of a set of candidate schemas. On the basis of the set of candidate schemas, 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 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 approach is particulary suitable to Intranets, while allowing for a smooth migration of Internet Web sites as more and more of them are produced via computer assisted design and generation