Editorial  (pp187-188)
        F. Frasincar, M. Gaedke, and G-J Houben        
Research articles:
Heterogeneous Data Translation through XML Conversion (pp189-204)
        P. Papotti and R. Torlone
In this paper, we illustrate an approach to the translation of Web data between heterogeneous formats. This work fits into a larger project whose aim is the development of a tool for the management of data described according to a large variety of models and formats used on the Web and the automatic translation of schemes and instances from one model to another. Data translations operate over XML representations of schemes and instances and rely on a uniform description of models that we call metamodel. The metamodel shows structural diversities and dictates the needed transformations. Complex translations are derived automatically by combining a number of predefined basic procedures. These procedures perform XML transformations and are implemented by means of XML query languages. Practical examples are provided to show the effectiveness of the approach.

A Generic Framework for Extracting XML Data from Legacy Databases (pp205-223)
        Ph. Thiran, F. Estiévenart, J-L. Hainaut, and G-J. Houben
This paper describes a generic framework in which semantics-based XML data can be derived from legacy databases. It consists of first recovering the conceptual schema of the database through reverse engineering techniques, and then of converting this schema, or part of it, into XML-compliant data structures. Both steps heavily rely on generic schema transformation techniques, while all the schemas involved in the whole process are expressed in a unique model, named GER. Transformations between schemas are expressed as sequences of reversible transformation primitives. The reversed sequence can be used to automatically translate query, data or updates posed on XML.

An Agent-oriented Approach to the Integration of Information Sources  (pp224-243)
        M. Christoffel, G. Wojke, S. Werner, R. Rezek, and S. Xu
The success of the Internet and the World Wide Web opened new ways of information supply. While more and more information sources become available, people are faced with the problem of information overload. New kinds of information systems are needed. They give people searching for information the opportunity to participate in the new development and profit from the new information sources that become available through the Web. A special challenge for Web information system modelling arises from the openness of the system: Everything is liable to change, and information sources come and go without further notice. In this paper, we present an approach to a flexible information system that is able to adapt to a dynamic environment. This approach is based on the idea of an open and dynamic information market with independent and autonomous providers and customers. We present the agent-oriented architecture of the information system and its realization in the application domain of scientific literature.

OntoWeaver: an Ontology-based Approach to the Design of Data-intensive Web Sites (pp244-262)
        Y.-G. Lei, E. Motta,  and J. Domingue
Building a data-intensive web site is a complex task. Ad hoc rapid prototyping approaches easily lead to unsatisfactory results, e.g. poor maintainability and extensibility. To address this problem, a number of model-based approaches have been proposed, which attempt to simplify the design and development of data-intensive web sites. However, these approaches typically lack expressive meta-models and, as a result, suffer from a number of limitations, e.g. the lack of appropriate support for the creation of complex user interfaces, for the specification of layouts and presentation styles, and for customization.
        In this paper we describe a new software tool OntoWeaver, which uses ontologies to drive the design and development of data-intensive web sites. OntoWeaver overcomes the problems of current approaches by providing a site view ontology, a presentation ontology, and a customization framework. Specifically, the site view ontology provides fine-grained modelling support for the creation of complex user interfaces and navigation structures. The presentation ontology captures the features of layouts and presentation styles of user interface elements. These two explicit meta-models allow the target web site to be represented in a declarative and re-usable format, thus enabling high level support for design, maintenance, and customization. The customization framework exploits this advantage and provides comprehensive customization support for the target web site at design as well as run time.

Sharing Learner Information through a Web Services-based Learning Architecture (pp263-278)
        D. Musa  and J. Palazzo  
This paper introduces the architecture developed for the exchange of learners model information among e-learning systems in the AdaptWeb Project. This Web-learning environment offers an adaptive content associated with a particular student’s profile. Hypermedia teaching applications may explore different educational strategies and tactics, including guided navigation, hierarchical contents presentation, examples, exercises, and so on. Also the teaching task can be optimized if the teacher prepares a content material that can be shared for different target public. AdaptWeb was designed concerning these aspects and allows the generation of different presentations from an ample learning material developed for a specific discipline based on the learner model.   The Web Service technology is used as it yields an easy communication between Web-applications through the HTTS protocol allowing also secure personal data interchange. Our goal in this work is to provide a standard communication protocol that makes possible different e-learning systems cooperate in order to gather a set of learner model information, richer than that found in a standalone e-learning system. As result, the course content, in a compliant federated e-learning system may be better adapted and presented to students, according to each student’s program, cognitive characteristics, and navigation preferences. Once the student profile is determined all the courses will be consistently offered by the e-learning systems using the same shared profile.

Book Reviews:
On “Web Engineering: Principles and Techniques” ed. by Woojong Suh (pp279-280)
      B. White

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