Semantic models in Web based Educational System integration

International audienceWeb based e-Education systems are an important kind of information systems that benefited from Web standards for implementation, deployment and integration. In this paper we propose and evaluate a semantic Web approach to support the features and interoperability of a real industrial e-Education system in production. We show how ontology-based knowledge representation supports the required features, their extension to new ones and the integration of external resources (e.g. official standards) as well as the interoperability with other systems.We designed and implemented a proof of concept in an industrial context that was qualitatively and quantitatively evaluated and we benchmarked different alternatives on real data and real queries. We present a complete evaluation of the quality of service and response time in this industrial context and we show that on a real-world tesbed Semantic Web based solutions can meet the industrial requirements, both in terms of functionalities and efficiency compared to existing operational solutions. We also show that an ontology-oriented modelling opens up new opportunities of advanced functionalities supporting resource recommendation and adaptive learning

A design space for RDF data representations

RDF triplestores' ability to store and query knowledge bases augmented with semantic annotations has attracted the attention of both research and industry. A multitude of systems offer varying data representation and indexing schemes. However, as recently shown for designing data structures, many design choices are biased by outdated considerations and may not result in the most efficient data representation for a given query workload. To overcome this limitation, we identify a novel three-dimensional design space. Within this design space, we map the trade-offs between different RDF data representations employed as part of an RDF triplestore and identify unexplored solutions. We complement the review with an empirical evaluation of ten standard SPARQL benchmarks to examine the prevalence of these access patterns in synthetic and real query workloads. We find some access patterns, to be both prevalent in the workloads and under-supported by existing triplestores. This shows the capabilities of our model to be used by RDF store designers to reason about different design choices and allow a (possibly artificially intelligent) designer to evaluate the fit between a given system design and a query workload