Semantic overlays in educational content networks – the hylOs approach

Abstract

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. 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. In this present paper, we briefly introduce our educational content management system hylOs. Enabled through an advanced authoring toolset, hylOs allows the definition of instructional overlays of a given eLearning object mesh. Based on a newly introduced Ontological Eval¬uation Layer, additional 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. The Hypermedia Learning Objects System (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.