Ontology-based Information Integration

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A diploma thesis:
OntoEdit-Based Mapping of Ontologies onto LDAP

The Internet as an enormous large heterogeneous information repository is witnessing the need to better utilize the available information by operating under a common query interface. Limiting the domain of integration to a predefined collection of terms and their relationships in form of ontologies makes the problem of integration easier. The purpose of this project is therefore to develop and implement an ontology-based information integration system. To provide support for data integration, we avoid "dirtying" sources or ontologies with semantic annotations necessary for integration and instead introduce a middleware in our system to hold such annotations.

The XML is on the way to prevail over all other existing data representation formats in the Web (HTML). Hence, to keep pace with current trends, we consider the system should without fail be XML-compatible. Due to a close resemblance between XML and LDAP models (hierarchical, simple, flexibile, extensibile, etc.) and to allow for a seamless integration of source data, schemata discrepancies and semantic information under a common framework, we put the LDAP standard technology in a middleware. Except to hold annotations, the LDAP middleware serves at the same time as a medium for a stable and efficient storage of ontologies in our system.

To survey, the whole paradigm discerns with two advantageous features:

• it provides a light-weight global access to the content of XML data through a common ontology in XML from anywhere in the network, and
• it performs a seamless integration of data, keeping the inner mixture of allocation of data, their schemas and semantics transparent to the user.

• Ontology-Based Querying of Linked XML Documents, Lule Ahmedi, Georg Lausen; Semantic Web Workshop at The 11th International World Wide Web Conference (WWW 2002), May, 7-11, 2002, Honolulu, Hawaii, USA.
• Ontology-based Access to Heterogeneous XML Data, Lule Ahmedi, Pedro José Marrón, Georg Lausen, Int. Workshop on Web Databases, Sept. 26-28, 2001, Vienna, Austria.
• Directory-Based Ontologies for Integrating XML Data, Lule Ahmedi, Int. Workshop on Foundations of Models and Languages for Data and Objects (FMLDO 2001), Sept. 16-18, 2001, Viterbo, Italy. To appear with Springer LNCS.
• LDAP-based Ontology for Information Integration, Lule Ahmedi, Pedro José Marrón, Georg Lausen, Datenbanksysteme in Büro, Technik und Wissenschaft (BTW), Oldenburg, 2001.

The project is being developed as a part of the HLCaches project in paralel with two other projects in the group:

• Internet Technologies
• Rewriting Queries with Caches

Some important links on the field in general are:

• A list of projects on information integration
• Some other projects on information integration: OntoBroker, OBSERVER, MOMIS
• On-To-Knowledge
• SemanticWeb.org
• Ontology.Org
• Lightweight Directory Access Protocol (LDAP)
• An LDAP Roadmap & FAQ collected by Jeff Hodges
• Innosoft's survey of various LDAP implementations worldwide
• LDAP Browser/Editor

• Prof. Dr. Georg Lausen, Freiburg University, lausen@informatik.uni-freiburg.de
• Lule Ahmedi, CS PhD candidate, ahmedi@informatik.uni-freiburg.de

The project is partially supported under "Spontaneous Integration of Heterogeneous Information from Web" by the Deutsche Forschungsgemeinschaft (DFG).