HPG: the Hera Presentation Generator

This paper presents a model-based design and development environment for Web Information Systems (WISs) using Semantic Web technologies. This environment called the Hera Presentation Generator (HPG) integrates a number of software tools created for the presentation generation phase of the Hera methodology. These tools are the HPG model builders that help constructing the WIS input specifications and the HPG engine that implements the data transformations involved in a WIS. There are two versions of the HPG engine: HPG-XSLT and HPG-Java. HPG-XSLT is characterized by the use of XSLT stylesheets for the data transformations and by the full generation of a Web presentation. HPG-Java uses Java code for the data transformations and thus exploits more than HPG-XSLT the RDF(S) semantics captured in the Hera models and builds one-page-at-a-time. Generating one-page-at-a-time is motivated by recent extensions to the Hera methodology in order to better sustain the building of WISs with richer user interaction support (e.g., form-based). Nevertheless, HPG-Java lost the declarativity, simplicity, and reuse capabilities of the XSLT transformation templates. HPG thus fills the existing gap for tool support for the design of WIS using Semantic Web technologies.