1. The HERMES Heterogeneous Reasoning and Mediator System V.S. Subrahmanian University of Maryland [These slides originated from the HERMES Project sponsored by DARPA’s Intelligent Information Integration Program from 1993 to 1996.]

2. 2 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.

3. 3 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.

4. 4 HERMES Platforms SunOS 4.1.3, Solaris, Linux Windows 3.1, Windows NT

5. 5 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

6. 6 Package Integration HERMES mediators make calls to external data sources using the syntax: p:f( ) 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.

7. 7 Semantic Integration HERMES uses a rule-based language to semantically integrate external data. in(X, p:f( )) 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( ).

8. 8 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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12. 12 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.

13. 13 More HERMES Information V.S. Subrahmanian, Professor Department of Computer Science University of Maryland College Park, MD 20742 Telephone: (301) 405-6724 E-mail: vs@cs.umd.edu URL: www.cs.umd.edu/~vs