List of Figurs. List of Tables. Preface. Acknowledgements. Foreword by Michael N. Huhns. 1. Introduction. 2. Metadata and Ontologies. 3. Metadata-Based Architectures. 4. Metadata-Based Brokering for Digital Data. 5. Capturing Information Content in Structured Data. 6. The Infosleuth System. 7. Vocabulary Brokering in the Observer System. 8. An Illustrative Example. 9. Related Work. 10. Conclusion. References. Index.