摘要：This paper describes how the Astronomy case study is modelled, created and executed, using a IMS LD ontology. The ontology was aimed at overcoming the expressiveness limitations of the IMS LD XML Schema by means of a taxonomy of concepts and a set of formally defined axioms. With regard to the authoring (creation) stage, the ontology has been used to enable the automatic validation of IMS LD documents in WebLD, a web authoring tool to create IMS LD Units of Learning. With regard to the execution stage, a service-oriented architecture was developed to allow the execution of IMS LD Units of Learning, whose learning processes have been modelled through Petri Nets.
关键词：IMS Learning Design; ontologies; authoring tools; execution engines; workflows; Petri nets; units of learning
