Querying structured documents with hypertext links using OODBMS

Hierarchical logical structure and hypertext links are complementary and can be combined to build more powerful document management systems. Previous work exploits this complementarity for building better document processors, browsers and editing tools, but not for building sophisticated querying mechanisms. Querying in hypertext has been a requirement since [19] and has already been elaborated in many hypertext systems, but has not yet been used for hypertext systems superimposed on an underlying hierarchical logical structure. In this paper we use the model and the SQL-like query language of [10] in order to manage structured documents with hypertext links. The model represents a structured documents with hypertext links. The model represents a structured document with typed links as a complex object, and uses paths through the document structure, as first class citizens in formulating queries. Several examples of queries illustrate, from a practical point of view, the expressive power of the language to retrieve documents, even without exact knowledge of their structure in a simple and homogeneous fashion. It must be stressed that the proposed model and language implement the equivalent HyTime Location Address Module. In fact, the language is more powerful than the corresponding HyQ query facilities. The implementation and the description throughout the paper use the SGML standard to represent the document structure and the object-oriented DBMS O2 to implement the query language and the storage module.