Ontologie-basierter Mediator zum Zugriff auf heterogene und verteilte Lerninhalte

Philipp Kärger

Mastersthesis Universität des Saarlandes 3/2006.


In modern e-learning systems so-called learning objects are used to impart knowledge. A learning object can contain several kinds of media such as texts, pictures, interactive applets, etc. More often than not, each e-learning system uses a proprietary repository of learning objects. That raises issues of interoperability and reusability of learning objects. In this diploma thesis an architecture is proposed which provides a mediating component that allows an e-learning system to retrieve learning objects not exclusively from its own learning object repository but also from other repositories. The developed mediator provides an interface which accepts uniform queries and passes these queries to the connected repositories. The mediator resolves the problem of heterogeneity by providing an ontology-based query rewriting mechanism, which translates the queries into a format understood by each different data source. This approach was implemented for the Web-based, intelligent e-learning system ActiveMath and allows the course generator of ActiveMath to access four different learning object repositories.

Deutsches Forschungszentrum für Künstliche Intelligenz
German Research Center for Artificial Intelligence