Coping with Limited Capabilities of Sources

  • Hector Garcia-Molina
  • Ramana Yerneni
Part of the Informatik aktuell book series (INFORMAT)


In various contexts (e.g., the Internet), the query-processing capabilities of data sources may be limited. Middleware systems based on a mediation architecture are employed to provide powerful query processing interfaces to data sources with limited query capabilities. Such systems also provide integrated views to the data across multiple sources. In this paper, we discuss how the query capabilities of data sources can be described and how mediators support extended query sets over the data sources. We also describe how the set of queries supported by a mediator can be computed from the corresponding sets of queries supported by the data sources integrated by the mediator. We present ways in which content description of data sources can help in extending the set of supported queries Finally, we describe the challenges posed by diverse source capabilities when supporting robust query processing through replicated sources in the presence of source failures.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    M. Carey, et al. Towards heterogeneous multimedia information systems: the Garlic approach. RIDE Workshop, 1995.Google Scholar
  2. 2.
    S. Chawathe, et al. The TSIMMIS Project: Integration of Heterogeneous Information Sources. In IPSJ Journal, 1994.Google Scholar
  3. 3.
    H. Garcia-Molina, W. Labio, R. Yerneni. Capability-sensitive Query Processing over Internet Sources. In Proc. ICDE Conference, 1999.Google Scholar
  4. 4.
    L. Haas, D. Kossman, E. Wimmers, J. Yang. Optimizing Queries Across Diverse Data Sources. In Proc. VLDB Conference, 1997.Google Scholar
  5. 5.
    J. Hammer, H. Garcia-Molina, S. Nestorov, R. Yerneni, M. Breunig, V. Vassalos. Template-Based Wrappers in the TSIMMIS System. In Proc. ACM SIGMOD Conference, 1996.Google Scholar
  6. 6.
    O. Kapitskaia, A. Tomasic, P. Valduriez. Scaling Heterogeneous Databases and the Design of DISCO. INRIA Technical Report, 1997.Google Scholar
  7. 7.
    T. Kirk, A. Levy, Y. Sagiv, D. Srivastava. The Information Manifold. In AAAI Symposium on Information Gathering in Distributed Heterogeneous Environment, 1995.Google Scholar
  8. 8.
    A. Levy, A. Rajaraman, J. Ordille. Querying Heterogeneous Information Sources Using Source Descriptions. In Proc. VLDB Conference, 1996.Google Scholar
  9. 9.
    A. Levy, M. Rousset. CARIN: A Representation Language Integrating Horn Rules and Description Logics. AT & T Technical Report, 1995.Google Scholar
  10. 10.
    A. Levy, Y. Sagiv. Constraints and Redundancy in Datalog. In Proc. PODS Conference, 1992.Google Scholar
  11. 11.
    C. Li, R. Yerneni, V. Vassalos, Y. Papakonstantinou, H. Garcia-Molina, J. Ullman. Capability Based Mediation in TSIMMIS. In Proc. ACM SIGMOD Conference, 1998.Google Scholar
  12. 12.
    Y. Papakonstantinou, H. Garcia-Molina, J. Ullman. Medmaker: A Mediation System Based on Declarative Specifications. In Proc. ICDE Conference, 1996.Google Scholar
  13. 13.
    Y. Papakonstantinou, H. Garcia-Molina, J. Widom. Object Exchange across Heterogeneous Information Sources. In Proc. ICDE Conference, 251–260, 1995.Google Scholar
  14. 14.
    Y. Papakonstantinou, A. Gupta, L. Haas. Capabilities-based Query Rewriting in Mediator Systems. In Proc. PDIS Conference, 1996.Google Scholar
  15. 15.
    A. Tomasic, L. Raschid, P. Valduriez. Dealing with Discrepancies in Wrapper Functionality. In Proc. ICDCS Conference, 1996.Google Scholar
  16. 16.
    G. Wiederhold. Mediators in the Architecture of Future Information Systems. In IEEE Computer, 25:38–49, 1992.Google Scholar
  17. 17.
    R. Yerneni, C. Li, H. Garcia-Molina, J. Ullman. Computing Capabilities of Mediators - Extended Version. , Stanford Technical Report, 1998.
  18. 18.
    R. Yerneni, C. Li, J. Ullman, H. Garcia-Molina. Optimizing Large Join Queries in Mediation Systems. In Proc. ICDT Conference, 1999.Google Scholar
  19. 19. Query Forms. December 15, 1998.
  20. 20. Web Site. / December 15, 1998.
  21. 21.
    Author-Title-Format-Subject Query Form for / December 15, 1998.
  22. 22.
    ISBN Query Form for / December 15, 1998.
  23. 23.
    Keywords-Publisher-Date Query Form for / December 15, 1998.
  24. 24. Query Form. December 15, 1998.
  25. 25.
    Compaq Shopping Guide for Books. December 15, 1998.
  26. 26.
    Extensible Markup Language (XML) 1.0: Proposed Recommendation. December 15, 1998.

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Hector Garcia-Molina
    • 1
  • Ramana Yerneni
    • 2
  1. 1.Stanford UniversityUSA
  2. 2.Stanford UniversityUSA

Personalised recommendations