Vol.2 No.1&2 September, 2003

In This Issue (pp001-002)
        D Schwabe      
Research Articles and Reviews:      
Engineering Semantic Web Information Systems in Hera (pp003-026)
        R. Vdovjak, F. Frasincar, G.J. Houben and P. Barna
The success of the World Wide Web has caused the concept of information system to change. Web Information Systems (WIS) use from the Web its paradigm and technologies in order to retrieve information from sources on the Web, and to present the information in terms of a Web or hypermedia presentation. Hera is a methodology that supports the design and engineering of WIS. It is a model-driven methodology that distinguishes three parts in the design: integration, data retrieval, and presentation generation. The integration part manages the gathering of data from different sources on the basis of source ontologies and mappings between those source ontologies and the conceptual model of the WIS. The data retrieval part handles the user queries and produces the data that represents the query result. In the presentation generation part this query result is transformed into a Web presentation and that presentation is constructed to suit the user (platform), e.g.\ HTML, WML, or SMIL. In this paper we address the Hera design methodology and specifically explain two models: the integration model that covers the different aspects of integration, and the adaptation model that specifies how the generated presentations can be adaptable (e.g.\ based on device capabilities, user preferences) and adaptive (e.g.\ based on user browsing history). This detailed description includes an explanation of how the Hera software is constructed. This software provides a set of transformations that allow a WIS to go from integration to presentation generation. These transformations are based on RDF(S), the foundation of the Semantic Web. We show how RDF(S) has proven its value in combining all relevant aspects of WIS design, thus illustrating how Hera allows the engineering of Semantic Web Information Systems (SWIS).

A Progressive Access Approach for Web-based Information Systems  (pp027-057)
        M. Villanova-Oliver, J. Gensel and H. Martin
Web-based Information Systems (WIS) are used for processing and diffusing large amounts of information over the Internet. It is therefore crucial to adapt to users both the content and the presentation of information in order to save them from some disorientation or cognitive overload syndromes. For this purpose, we introduce the notion of Progressive Access which aims at giving users through the WIS functionalities a flexible and personalized access to data, by stratifying their information space. These stratifications are described by a Progressive Access Model (PAM). We present here the PAM and its connections with four other models (data model, functional model, hypermedia model, user model). We show how these five models can be exploited for the design of an adaptable WIS which integrates the progressive access approach. Design and generation of such systems are supported by a platform called KIWIS we also present in the paper and illustrate by an example.

A Component-based Approach for Adaptive, Dynamic Web Documents (pp058-073)
        Z. Fiala, M. Hinz, K. Meissner and F. Wehner
Personalized Web applications automatically adapted for different clients and user preferences gain more importance. Still, there are barely technologies to compensate the additional effort of creating, maintaining and publishing such Web content. To address this problem, this paper introduces a declarative, component-based approach for adaptive, dynamic Web documents on the basis of XML-technology. Adaptive Web components on different abstraction levels are defined in order to support effective Web page authoring and generation. Media components encapsulate concrete media assets by describing them with technical metadata. Content units group media components belonging together semantically by declaring their layout in a device-independent way. Finally, hierarchical document components playing a specific semantic role are defined. The hyperlink view for defining typed links is spanned over all component layers. Beside the reuse of both implementation artefacts and higher level concepts, the model also allows to define adaptive behavior of components in a fine-granular way. As a further benefit the support for ubiquitous collaboration via component annotations is introduced. Finally, the stepwise pipeline-based process of document generation is introduced and performance issues are sketched.

Link-Independent Navigation Support in Web-Based Adaptive Hypermedia (pp074-089)
        P. De Bra
Many websites offer their users a lot of freedom to navigate through a large hyperspace. Some sites offer navigation or orientation support in the form of (complete or partial) site maps or guided tours. Some sites also use adaptive hypermedia techniques such as link annotation to help users find their way, based on an individual or group user model. In such systems the navigation support is often tied to the existing link structure. In this paper we discuss how websites can also offer adaptive navigation and orientation support like site maps and guided tours that are independent of the underlying link structure of the website. In particular, we show how the AHAM model, introduced in [6], can represent such adaptive global or local orientation support. To this end we define Link-Independent Navigation Support (LINS) that provides the user a better understandable navigation environment and a strong connection among pages at different abstraction levels in hyperspace. AHAM provides a design platform to define all kinds of relationship graphs, called abstract views in this paper. Abstract views describe connectivity among concepts independently from the basic link structure of the underlying hyperspace, and LINS is based on abstract views.

Techniques and Metrics For Improving Website Structure (pp090-114)
        E. Christopoulou, J. Garofalakis, C. Makris, Y. Panagis, A. Psaras-Chatzigeorgiou, E. Sakkopoulos and A. Tsakalidis
Evaluation of the link structure of a web site and its redefinition to achieve increased efficiency with regard to easier information retrieval is a common problem in website development. Nevertheless much effort has been devoted in order to analyze the overall statistical properties of a web site, rather than to assess the actual value of its pages. In this paper two distinct metrics are proposed, which aim to quantify the importance of a web page based on the visits it receives by the users and its location within the website. Subsequently, certain guidelines are presented, which can be used to reorganize the website, taking into account the optimization of these metrics. Finally we evaluate the proposed algorithms using real-world website data and verify that they exhibit more elaborate behavior than a related simpler technique.

The 2QCV3Q Quality Model for the Analysiy of Web site Requirements (pp115-127)
        L. Mich, M. Franch, and G. Cilione
Requirements analysis constitutes a critical phase in the  development of software systems, and for Web sites it can often be a determining factor in the success of the company or organisation. A thorough requirements elicitation will take into considerations the objectives and needs of all the actors involved. It is therefore important for an analyst to have conceptual instruments that support their identification, taking into account the different components of a Web site. In this paper we propose the application of a quality model - the 2QCV3Q meta-model - to the activities related to the requirements engineering process. To illustrate this we describe the requirements analysis for an ONLUS organisation called "No Pain for Children", a nonprofit association for promotion of analgesic treatment. Developed to evaluate the quality of existing Web sites, the meta-model proved to be a useful tool also in gathering and negotiating the requirements. In particular, it was possible to highlight from its conception the priorities of the newly founded association and also the potential areas of conflict between the objectives of the association (and its promoters) and the needs of the doctors and families involved with it. 

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