Semantic Web Application Modeling

Abstract

The Semantic Web and the Web service paradigm are currently the most important trends on the way to the next generation of the Web. They promise new opportunities for content and service provision, enabling manifold and flexible new applications and improved support for individual and cooperative tasks. The use of the Web service paradigm in the development of Web applications, that typically couple application databases with user dialogs, is quite obvious. The development of Web applications that can be operated effectively in the Semantic Web context (Semantic Web Applications), however, imposes some challenges. Two main challenges towards extended (conceptual) modeling support are addressed in this talk:

• In the Semantic Web, Web applications move from a purely human user community towards a mixed user community consisting of humans as well as of software agents; this results into new requirements towards models for Web applications’ user interfaces;

• Automatic interpretation of content, one of the main building blocks of the Semantic Web, is based on interlinking local models with globally defined interpretation schemes like vocabularies and ontologies; this has to be reflected by the conceptual application domain models of Semantic Web Applications.

Conceptual Modeling for Web applications, thus, has to be revisited in the context of the new Web trends looking for adequate Semantic Web Application Models.

In Web applications dialog-oriented (in most cases form-based) user interface models are state-of-the art for the interaction with users. The requirement of representing interaction with humans as well as with software agents is best met by a user interface model that describes the dialogs with the system on a conceptual level that can be dynamically translated into a (user) interface language adequate for the respective “user” (human or agent). The upcoming Web standard XForms for the next generation of form-based user interfaces is a good example of such a conceptual user interface model. For the linking of globally defined concepts with local domain model concepts one of the most popular models in the context of the Semantic Web is provided by the Resource Description Framework (RDF). The systematic integration of Uniform Resource Identifiers (URIs) into the model facilitates references to vocabularies and ontologies defined e.g. as RDF Schema or OWL ontology. However, for using RDF in Web applications a coupling between these “semantic” data models and the more traditional data models underlying the application data is necessary.

In addition to the aforementioned requirements, models, and approaches, the talk discusses a framework for the development of semantic-enabled Web applications designed at Fraunhofer IPSI. This approach combines semi-automatically extracted RDF-based domain models with an XForms-based conceptual user interface model, and application logic encoded in Web services. Within a corresponding application development framework, so-called Web application authoring tools support general model management, definition and management of domain model views and the definition and automatic run-time operazionalization of flexible couplings between the domain model, conceptual UI model, and application logic, i.e. between the components of the semantic web application model.