SUBCONTRACTORS: None

PRINCIPAL INVESTIGATORS: Hector Garcia-Molina, hector@cs.stanford.edu, (415) 723-0685

TITLE OF EFFORT: An Integrated Information Management System

OBJECTIVE: To develop a next generation information management system that will provide integrated access to a wide variety of information and knowledge sources. The system will manage or provide access to unstructured text data, such as newswire stories and files, to conventional structured databases, and to raw data, e.g., from satellite images and simulation experiments. Through this system a decision maker will be able to find information of interest, fuse information from different sources, and process it (e.g., summarize it, visualize it, discover trends). In addition to supporting extraction of information, the system will provide tools for monitoring and enforcing constraints across heterogeneous information repositories (example: the fuel price used in planning a mission should be the minimum of the prices reported by three suppliers, except if the fuel cannot be delivered in time from that supplier).

APPROACH: Approach is to build and demonstrate three components: translators, mediators, and constraint managers. Translators are wrappers that convert commands and information to and from sources into a common object model and command language. Mediators can combine information from several sources, performing fusion and integration. Constraint managers enforce constraints or detect their violations in a distributed fashion, using whatever capabilities are available at the underlying sources. The technology for rapid implementation of translators and mediators, based on high level descriptions of their functionality, will also be developed.

PROGRESS: A simple yet powerful Object Exchange Model has been developed, together with a SQL-like query language. Based on these, several translators and mediators have been implemented and demonstrated on a collection of heterogeneous bibliographic information sources. Two generic information browsing tools, one for a PC and one based on Mosaic, have been implemented and demonstrated. Basic technology and an initial prototype for constraint management have been developed.

PRODUCTS: None

FY94 ACCOMPLISHMENTS:

• Developed Object Exchange Model (OEM) and its Query Language (OEM-QL).
• Implemented various translators and mediators, and demonstrated them on a collection of heterogeneous bibliographic information sources.
• Implemented two browsing interfaces for accessing the mediators and the sources.
• Developed a framework for enforcing constraints across information sources with widely varying structure and capabilities.
• Implemented and demonstrated a first prototype of a toolkit for enforcing constraints.

FY-95 PLANS:

• Develop a simple translator generator that can take as input a high level description of the inputs and outputs for a given source, and can produce as output a translator for the source.
• Develop a simple mediator generator that can take as input a high level description of the sources involved and the integration work to be done, and outputs a working mediator.
• Extend the capabilities of the constraint management toolkit, for example, so it can cope with source failures and can handle more complex constraints.

TECHNOLOGY TRANSITION: Once the translator and mediator generators are developed, they will be demonstrated at other I3 sites.

PUBLICATIONS:

• Yannis Papakonstantinou, Hector Garcia-Molina and Jennifer Widom, "Object Exchange Across Heterogeneous Information Sources," IEEE International Conference on Data Engineering, March 1995, to appear. (Also available via anonymous FTP from host db.stanford.edu file /pub/papakonstantinou/1994/object-exchange-heterogeneous-is.ps.)

• Sudarshan Chawathe, Hector Garcia-Molina and Jennifer Widom, "Flexible Constraint Management for Autonomous Distributed Databases," IEEE Data Engineering Bulletin, Vol. 17, No. 2, June 1994, pp. 23-27. (Also available via anonymous FTP from host db.stanford.edu file /pub/chawathe/1994/autonomous-cm.ps.)

• Sudarshan Chawathe, Hector Garcia-Molina and Jennifer Widom, "Constraint Management in Loosely Coupled Distributed Databases," submitted for journal publication. (Also available via anonymous FTP from host db.stanford.edu, file /pub/chawathe/1994/cm.ps.)

DATE PREPARED: August 21, 1994

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