Layered RDF: An object-oriented approach to web information representation

Abstract

Based on XML, RDF(S) has been recommended as the basic layer of the Semantic Web, providing a foundation for the higher layers of ontology, logic and trust. Although RDF(S) enables specification and identification of data and relationships between data, it has some limitations as a foundational language of the Semantic Web. Firstly, the unconstrained framework of the RDF Schema makes it hard to share information from different sources. Furthermore, RDF(S) has limited expres-siveness as a vocabulary description language, which is partly due to insufficient object-oriented features. Finally, the unclear semantics of RDF(S), caused by language constructs with dual roles, impede any approach to provide reasoning support for the language. To overcome some of the limitations, this paper presents Layered RDF, a web information representation language based on RDF(S). Layered RDF distinguishes schema information from instance information by having separated layers. Furthermore, Layered RDF provides more powerful schema mechanisms than does RDF Schema, by incorporating object-oriented features such as inheritance and polymorphism.