Gio Wiederhold

Computer Science Department, Stanford University

We have worked for many years on information architectures which are intended to provided extra value to the customers, beyond the value provided by the information sources. The modules, called Mediators are interposed between databases and other information sources, and client applications. They often carry out the roles that used to be performed by human intermediaries, as reviewers, abstracters, critics, writers of surveys and anthologies, staff experts, advices givers as consumer organizations and colleagues, librarians, and the person sitting next to you on a bus. We have less access to such human resources now. The resulting disintermediation leads to problems of access, information overload, and maintenance of sharable information resources. We observed that there were many ad-hoc tools and aproaches being developed to deal with this issue, including work in our own DARPA-funded KBMS project. An early paper, mapping earlier work into a simple concept and architecture was written in 1991:

    Wiederhold, Gio: "Mediators in the Architecture of Future Information Systems"; later published in IEEE Computer, March 1992, pages 38-49. Two associated figures are
    3. Data and Knowledge Loops (ps) or (gif)
    5. Layers and interfaces (ps) or (gif).

A set of viewgraphs summarizing the approach and indicating recent work at Stanford is

    Mediator Technology; various dates

Architectural choices are discussed in Wiederhold, Gio and Michael Genesereth: "The Conceptual Basis for Mediation Services (ps of Source)"; IEEE Expert, Vol.12 No.5, Sep.-Oct. 1997. A later paper, "Weaving Data into Information", summarizes the state of the art, including practical applications was published in Database Programming & Design, Freeman pubs, September 1998,

    DBPD Mediators (html - Source), March 1998.
    Slides from a tutorial, including a status assessment and directions for future work, given at the Herbstschule on Berlin, (html), October 1998 -- 112 viewgraphs (updated Oct.1999) .
    A report prepared for MITI, Trends in Information Technology, (1999) includes mediator concepts and business opportunities.
    Associated presentation slides, Oct 1999 (html).
    Associated presentation slides, Oct 1999 (powerpoint).

More details about current efforts is available about Stanford's InfoLab and
Gio's work on Large-scale Interoperation, Mediation, and Composition (LIC).

A list of commercial efforts in mediation is being maintained by us.

A more general I3 mediation web page, including research projects in Europe, the U.S., and around the world is being maintained by Holger Wache of the University of Bremen.
OMG now supports an `Interoperability Clearinghouse' dealing with similar concerns, but without intelligent middleware.

Gio's projects in Mediation

We are and have been engaged in a number of projects that deal with new paradigms for building, maintaining, and securing large computing systems. These often involve intermediary services at various levels (CODATA 97 viewgraphs), so that sharing becomes scalable. Papers on thses topics can also pe retrieved from my paperlist.
  1. Mediators for fusion of data for Environmental Restoration (ERIS) at the Idaho National Engineering Labs (INEL-ERIS) (ERIS). {Completed. Pursued now at INEEL, Idaho Falls ID.)
  2. Mediators which report the results of training exercises back to the planners, according to their objectives (MIFT) (completed).
  3. Intelligent Software Agents that Access PDQ and CANCERLIT for accessing cancer data. We supported Lexical Technology as part of a Small Business (SBIR) grant.
  4. A Simulation Access Language (SimQL) to demonstrate viability of a language (SimQL) which will permit integration and reuse of simulations within mediated information systems.
  5. Managing ontologies, and developing an Ontology Algebra to deal with semantic heterogeneity is the focus n our SKC project.
  6. Security mediators have been developed for protection of privacy as part of our Trusted Interoperation of Health Care Information (TIHI), Trusted Dissemination of Images (TID), and Secure Manufacturing (SAW) projects.


Interoperation projects overview page.