Querying Semantically Tagged Documents on the World-Wide Web

QUEST is a system for Querying Semantically Tagged documents on the World-Wide Web. The advent of new markup languages, such as xml, facilitates authoring of Web documents that contain not just html tags for instructing a browser how to view a document, but also contain objects that represent the semantic structure of the document. When such documents become widely available, more powerful methods to access and query information on the Web will be possible. The QUEST system was designed and implemented for querying and manipulating documents written in the markup language ohtml. ohtml combines html and objects of the oem data model. QUEST has several new features. First, QUEST can be used to query a combination of hypertext and object structures. Second, The results of queries are ohtml pages and thus of the same type as the data being queried. Third, QUEST implements a new approach for querying semistructured data that produces meaningful answers even when the input data is incomplete, i.e., when some variables of the query cannot be bound to database values. Finally, the experience of developing and using QUEST for querying semantic documents on the Web can be useful for the design and implementation of query languages for xml. This paper provides an overview of the QUEST system and its components.