Specification framework for engineering adaptive web applications

The growing demand for data-driven Web applications has led to the need for a structured and controlled approach to the engineering of such applications. Both designers and developers need a framework that in all stages of the engineering process allows them to specify the relevant aspects of the application. This paper concentrates on Web applications that automatically generate hypermedia presentations for their output. Typically, these applications retrieve their data from a heterogeneous set of Web data sources, and they respond to a user's request for information by providing the user with a hypermedia presentation for the requested data. Many classes of Web-based information systems are of this nature. Because of this aspect of automated presentation generation, (the support of) the engineering process for these applications is far from trivial. The engineering becomes even more complicated when we include notions of adaptation. Here, we address both adaptation during the presentation generation for the sake of personalization, for example to reflect user preferences or platform used, as well as adaptation inside the generated presentation (generating adaptive hypermedia). The specification framework that we present in this paper can be used in an engineering process of an adaptive Web application. This framework called Hera is related to design methodologies for Web applications, and in particular to RMM (Relationship Management Methodology) for its coverage of aspects of hypermedia design. Characteristically, Hera distinguishes between the logical, functional specification of the data and its actual presentation. By separating (1) the conceptual (or semantical) description of data, (2) the navigational aspects of its hypermedia presentation and (3) the rendering of that presentation, the process of designing the application improves significantly. Using new emerging Web technologies like RDF, XML, and XSLT, we have implemented a prototype to illustrate the use of this specification framework.