Towards a UML Extension for Hypermedia Design

The acceptance of UML as a de facto standard for the design of object-oriented systems, together with the explosive growth of the World Wide Web has raised the need for UML extensions to model hypermedia applications running on the Internet. In this paper we propose such an extension for modeling the navigation and the user interfaces of hypermedia systems. Similar to other design methods for hypermedia systems we view the design of hypermedia systems as consisting of three models: the conceptual, navigational and presentational model. The conceptual model consists of a class diagram identifying the objects of the problem domain and their relations. The navigational model describes the navigation structure of the hypermedia application by a class diagram specifying which navigational nodes are defined and an object diagram showing how these navigational nodes are visited. Finally, the presentational model describes the abstract user interface by composite objects and its dynamic behavior by state diagrams. Each model is built using the notations provided by the UML, applying the extension mechanism of the UML, i.e. stereotypes and OCL constraints, when necessary.