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Semantic overlays in educational content networks – the hylOs approach

Michael Engelhardt (FHTW Berlin, Germany)
Arne Hildebrand (FHTW Berlin, Germany)
Dagmar Lange (FHTW Berlin, Germany)
Thomas C. Schmidt (FHTW Berlin, Germany Fakultät Technik und Informatik, HAW Hamburg, Germany)

Campus-Wide Information Systems

ISSN: 1065-0741

Article publication date: 1 August 2006




The paper, aims to introduce an educational content management system Hypermedia Learning Objects System (hylOs), which is fully compliant to the IEEE LOM eLearning object metadata standard. Enabled through an advanced authoring toolset, hylOs allows the definition of instructional overlays of a given eLearning object mesh.


In educational content management, simple file distribution is considered insufficient. Instead, IEEE LOM standardised eLearning objects have been well established as the basic building blocks for educational online content. They are nicely suited for self‐explorative learning approaches within adaptive hypermedia applications. Even though eLearning objects typically reside within content repositories, they may propagate metadata relations beyond repository limits. Given the explicit meaning of these interobject references, a semantic net of content strings can be knotted, overlaying the repository infrastructure.


Based on a newly introduced ontological evaluation layer, meaningful overlay relations between knowledge objects are shown to derive autonomously. A technology framework to extend the resulting semantic nets beyond repository limits is also presented.

Research limitations/implications

This paper provides proof of concept for the derivation and use of semantic content networks in educational hypermedia. It thereby opens up new directions for future eLearning technologies and pedagogical adoption.

Practical implications

The paper illustrates capabilities of the hylOs eLearning content management. The hylOs is built upon the more general Media Information Repository (MIR) and the MIR Adaptive Context Linking Environment (MIRaCLE): its linking extension. MIR is an open system supporting the standard XML, CORBA and JNDI. hylOs benefits from manageable information structures, sophisticated access logic and high‐level authoring tools like the eLO editor responsible for the semi‐manual creation of meta data and WYSIWYG like XML–content editing, allowing for rapid distributed content development.


Over the last few years, networking technologies and distributed information systems have moved up the OSI layer and are established well within application‐centric middleware. Most recently, content overlay networks have matured, incorporating the semantics of data files into their self‐organisational structure with the aim of optimising data‐centric distributed indexing and retrieval. This paper elaborates a corresponding concept of semantic structuring for educational content objects. It introduces and analyses the autonomous generation and educational exploitation of semantic content nets, providing proof of concept by a full‐featured implementation within the hylOs educational content management system.



Engelhardt, M., Hildebrand, A., Lange, D. and Schmidt, T.C. (2006), "Semantic overlays in educational content networks – the hylOs approach", Campus-Wide Information Systems, Vol. 23 No. 4, pp. 254-267.



Emerald Group Publishing Limited

Copyright © 2006, Emerald Group Publishing Limited

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