Managing Semistructured Data with FLORID:
A Deductive Object-Oriented Perspective
Bertram Ludäscher, Rainer Himmeröder, Georg Lausen, Wolfgang May, and Christian Schlepphorst.
The closely related research areas management of
semistructured data and languages for querying the Web
have recently attracted a lot of interest. We argue that languages
supporting deduction and object-orientation (dood languages) are
particularly suited in this context: Object-orientation
provides a flexible common data model for combining information from
heterogeneous sources and for handling partial information.
Techniques for navigating in object-oriented databases can be
applied to semistructured databases as well, since the latter may be
viewed as (very simple) instances of the former. Deductive
rules provide a powerful framework for expressing complex queries
in a high-level, declarative programming style.
We elaborate on the management of semistructured data and show how reachability queries involving general path expressions and the extraction of data paths in the presence of cyclic data can be handled. We then propose a formal model for querying structure and contents of Web data and present its declarative semantics. A main advantage of our approach is that it brings together the above-mentioned issues in a unified, formal framework and---using the FLORID system---supports rapid prototyping and experimenting with all these features. Concrete examples illustrate the concise and elegant programming style supported by FLORID and substantiate the above-mentioned claims.