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 adaptivity. Here, we address both adaptation during the presentation generation for the sake of personalization (to reflect e.g. user preferences or platform used), as well as adaptation within the generated presentation (generating adaptive hypermedia). Th

An RMM-based methodology for hypermedia presentation design

Abstract. Due to the rapid growth of the Web, there is an increasing need for methodologies that support the design of Web-based Information Systems (WIS). After investigating the application of existing hypermedia design methodologies in the context of automated hypermedia presentation design we propose a specification framework for this context. The framework considers the possibility of dynamically gathering information from a collection of structured, but also possibly heterogeneous sources (relational or object-oriented databases, XML repositories etc.). The methodology associated with the framework shows two levels of abstraction: the logical level, and the presentation level. At the logical level the application diagram captures the design of slices, thus specifying the content related grouping of data elements and their relationships. At the presentation level, the presentation diagram bridges the logical level and the actual implementation by specifying how the design of slices is translated into hypermedia mechanisms, e.g. hyperlinks.

RDF Based Architecture for Semantic Integration of Heterogeneous

The proposed integration architecture aims at exploiting data semantics in order to provide a coherent and meaningful (with respect to a given conceptual model) view of the integrated heterogeneous information sources. The architecture is split into five separate layers to assure modularization, providing description, requirements, and interfaces for each. It favors the lazy retrieval paradigm over the data warehousing approach. The novelty of the architecture lies in the combination of semantic and on-demand driven retrieval. This line of attack offers several advantages but brings also challenges, both of which we discuss with respect to RDF, the architecture's underlying model

RAL: an Algebra for Querying RDF

To make the World Wide Web machine-understandable there is a strong demand both for languages describing metadata and for languages querying metadata. The Resource Description Framework (RDF), a language proposed by W3C, can be used for describing metadata about (Web) resources. RDF Schema (RDFS) extends RDF by providing means for creating application specific vocabularies (ontologies) . While the two above languages are widely acknowledged as a standard means for describing Web metadata, a standardized language for querying RDF metadata is still an open issue. Research groups coming both from industry and academia are presently involved in proposing several RDF query languages. Due to the lack of an RDF algebra such query languages use APIs to describe their semantics and optimization issues are mostly neglected. This paper proposes RAL (an RDF algebra) as a reference mathematical study for RDF query languages and for performing RDF query optimization. We define the data model, we present the operators to manipulate the data, and we address the application of RAL for query optimization. RAL includes: extraction operators to retrieve the needed resources from the input RDF model, loop operators to support repetition, and construction operators to build the resulting RDF model