University of Maryland Information Mediation
Project
The Information Mediation Project is jointly supported by the University of
Maryland Institute for Advanced
Computer Studies and by the Defense Advanced Research Projects
Agency (ARPA) under the sponsorship of the Office of Naval Research and by
the National Science Foundation. It is based in the Computational
Linguistics and Information Processing (CLIP)
Lab at UMIACS.
This project conducts research on mediator and translator technology,
for networked heterogeneous information servers. A semantic translator
supports interoperable query processing for relational (SQL) and object
(ODMG/OQL) databases. A canonical mapping knowledge base is constructed,
whose parameters resolve representational, schematic and semantic conflicts
among source and target schemas and provide translated queries in the
target language. Mediators based on the ODMG / OQL common data model and
query language, provide query reformulation based on semantic knowledge,
including integrity constraints, mapping rules, and information on data
replication. They also support query decomposition and optimization.
A prototype system based on O2-Web, the www interface to the O2 database
system, and SQl*Net, to access Oracle servers, is being constructed to
provide mediation and translation for O2 and Oracle databases. We are
also conducting research on extending the common data model to explicity
model data repositories, to support scalability of mediators and translators.
We are also studying flexible query processing techniques for netowrked
information servers. Research on KIF based intelligent agents is also
being studied, and we have developed KIF knowledge bases and meta-rules to
mediate among queries in relational, deductive and object data bases,
with dissimilar semantics.
Members of the Information Mediation Project
Recent papers
-
A Data Model and Query Processing Techniques for Scaling
Access to Distributed Heterogeneous Databases in Disco
- Tomasic, Anthony and Raschid, Louiqa and Valduriez, Patrick.
Invited paper in the IEEE Transactions on Computers, special
issue on Distributed Computing Systems, 1997.
-
Scaling Heterogeneous Databases and the Design of DISCO.
- Tomasic, Anthony and Raschid, Louiqa and Valduriez, Patrick.
Proceedings of the International Conference on Distributed
Computer Systems, 1996. Nominated for Best Paper Award.
long version
-
Using Heterogeneous Equivalences for Query Rewriting in Multidatabase Systems.
- Daniela Florescu and and Louiqa Raschid and Patrick Valduriez
Proceedings of the International Conference on Cooperative
Information Systems (CoopIS95), 1995.
-
A Methodology for Query Reformulation in CIS using Semantic Knowledge.
- Daniela Florescu and and Louiqa Raschid and Patrick Valduriez.
To appear in the International Journal of Intelligent and
Cooperative Information Systems, special issue on Formal Methods
in Cooperative Information Systems,
editors, Michael N. Huhns and Mukesh Singhal, 1996.
-
Answering Queries Using OQL View Expressions
- Daniela Florescu and and Louiqa Raschid and Patrick Valduriez.
Presented at the Workshop on Materialized Views: Techniques and Applications,
Montreal Canada, 1996.
-
A KIF Mediator for Multiple F-logic Object Databases
- Maria Esther Vidal and Louiqa Raschid.
Technical report, 1997.
-
Interoperable query processing from object to relational schemas based
on a parameterized canonical representation.
- Louiqa Raschid and Yahui Chang.
International Journal of Intelligent and Cooperative
Information Systems, 1995.
-
Query transformation techniques for interoperable query processing in cooperative information systems.
- Raschid, L., Chang, Y. and Dorr, B.
In the Proceedings of the Second International Conference on
Cooperative Information Systems (CoopIS94), May 17-20, Toronto, CA,
1994.
-
Transforming queries from a relational schema to an equivalent object schema: a prototype based on F-logic.
- Yahui Chang, Louiqa Raschid and Bonnie Dorr.
In the Proceedings of the International Symposium on Methodologies
in Information Systems, (ISMIS-94), October 1994.
A longer version of this paper is also
available as
longer version
-
Defining the search space for query optimization in a heterogeneous database management system.
- Daniela Florescu and Louiqa Raschid and Patrick Valduriez.
Under review.
-
Interoperable query processing among heterogeneous
databases.
- Yahui Chang.
University of Maryland technical report 94-67, 1994.
-
Query interoperation among object-oriented and relational
databases.
- Xiaolei Qian and Louiqa Raschid.
To appear in the the Proceedings of the International Conference
on Data Engineering, 1995.
-
Building Parameterized Canonical Representations to Achieve
Interoperability among Heterogeneous Databases.
- Yahui Chang and Louiqa Raschid.
In the Proceedings of the Sixth International Hong Kong
Computer Society Database Workshop on Database Re-engineering
and Interoperability, March 3-4, 1995, Kowloon, Hong Kong.