The HERMES Heterogeneous Reasoning and Mediator System V.S. Subrahmanian University of Maryland [These slides originated from the HERMES Project sponsored.

The HERMES HeterogeneousReasoning and Mediator System

V.S. SubrahmanianUniversity of Maryland

[These slides originated from the HERMES Project sponsored by DARPA’s Intelligent Information Integration Program from 1993

to 1996.]

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Motivation

Complex reasoning systems need to: access very diverse, heterogeneous

data sources across the Internet access different software packages

(also located across the Internet) to manipulate this data.

Mediators are programs that perform such integrations.

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HERMES Domains

Ingres, Paradox, dBase, flat files. Text databases. Multimedia data: image data, text

data, video. Reasoning systems: nonlinear

planner, Army terrain reasoner, face recognition algorithms.

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HERMES Platforms

SunOS 4.1.3, Solaris, Linux Windows 3.1, Windows NT

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HERMES Overview

HERMES is not a mediator. It is a platform for building mediators for different applications.

HERMES splits the task of building mediators into two tasks: Package Integration Semantic Integration

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Package Integration HERMES mediators make calls to

external data sources using the syntax:

p:f(<args>) This says “execute function f

defined in package p on the specified arguments.”

Package integration is the process by which predefined functions of external packages are executable in this way.

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Semantic Integration

HERMES uses a rule-based language to semantically integrate external data.

in(X, p:f(<args>)) is a special predicate that allows external accesses. It is satisfied if and only if X is in (or can be made to point to) an object returned by the call p:f(<args>).

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Semantic Integration (cont.)

Here is an example that accesses two data sources:in(X, ingres:select(‘facility.rel’, “Item”, “=“, “oscilloscope”)) &

in(Y, paradox:select(‘weather.rel’, “Place”, “=“, X.Location)) &

=(Y.WeatherMap, Map).

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WebHERMES Provides a simple HTML interface

that an end user may use to access multiple databases.

Provides facilities for automatic query relaxation.

Can access WWW sources as a result of a query. Connected to Lycos and InfoSeek WWW search engines.

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More HERMES Information

V.S. Subrahmanian, ProfessorDepartment of Computer Science University of MarylandCollege Park, MD 20742Telephone: (301) 405-6724E-mail: [email protected]: www.cs.umd.edu/~vs