Role-Oriented Models for Hypermedia Construction - Conceptual Modeling for the Semantic Web
Current hypermedia modeling techniques such as OOHDM, RMM or WebML rely on class-based domain models to guide the hyper- media construction process. In this paper we discuss the notion of role-oriented models as particularly suited for capturing differ- ent semantic contexts of hypermedia interfaces. The key idea is to allow resources to fill different roles which specify how these resources can be embedded in different link structures. After an overview of some class-oriented models, we discuss in detail the main features and benefits of role-oriented modeling compared to conventional class-oriented approaches, and make clear the distinc- tion between attributes and links associated with objects via their natural types and attributes and relationships for an object specified by the different roles the object can fill. Two detailed examples, one discussing the use of role-oriented models for the specification of link structures in learning materials, another one for the specifica- tion of contexts for a tourist information system, show how these role-oriented models can be applied in different areas. Finally we show how such models can be easily expressed and implemented using the W3C standard for web annotation, RDFS, and show that a role-oriented semantics is actually closer to the intended use of RDFS schemas than the "default" class-oriented semantics.