Project Overview

Welcome to the XPRESS project home page! We, CoBase research group, aim at building a novel XML Query Processing and Relaxation system in Relational Storage. XPRESS stands for "Xml Processing and Relaxation in rElational Storage System"

This project is under umbrella of the larger effort to build an intelligent information system in CoBae project supported by DARPA.

As World-Wide Web becomes a major mean of disseminating and sharing information, there is an exponential increase of the amount of data in web-compliant format such as HyperText Markup Language (HTML) and Extensible Markup Language (XML). Especially, XML has been recently getting a lot of attention as a possible candidate format due to its relative simplicity as compared to SGML and relative powerfulness as compared to HTML.

Building an efficient information system to handle such XML documents is a challenging task, involving many issues related to storage, index, query, user interface, etc. Two promising ways of implementing it are:

The first approach includes projects such as Lore at Stanford U. [SIGMOD 97] and the second approach includes projects such as STORED/SilkRoute at AT\&T Labs [SIGMOD 98], Niagara at U. Wisconsin [VLDB 99]. Each approach has its own strong edge in different aspects, but the second approach especially has the following benefits: It is also important to mention that this approach is not without its cons: In this research, we plan to investigate the second approach in a detailed and complete manner. Furthermore, we'd like to leverage on the mature CoBase techniques [ICDE 91, JIIS 94, JIIS 96] to cope with situations when no sufficient answers and found. Towards this goal, the following four functionalities are identified as illustrated in the Figure below:
  1. Mapping XML to Relational Model
  2. Rewriting XML Query to SQL
  3. Query Relaxation in XML
  4. Mapping Relational to XML Model

Last modified: Sun Sep 10 21:20:52 PDT 2000