Vol.6 No.4 December 25, 2007       
Engineering the Semantic Web

Editorial (pp281-282)
        F. Frasincar and P. Thiran

Research Articles:
An Infrastructure for Semantic Web Portals (pp283-308)
        Y.-G. Lei, V. Lopze, E. Motta, and V. Uren
This paper presents our Semantic Web portal infrastructure, which focuses on how to enhance knowledge access in traditional web portals by gathering and exploiting semantic metadata. Special attention is paid to three important issues that affect the performance of knowledge access: i) high quality metadata acquisition, which concerns how to ensure high quality while gathering semantic metadata from heterogeneous data sources; ii) semantic search, which addresses how to meet the information querying needs of ordinary end users who are not necessarily familiar with the problem domain or the supported query languages; and iii) semantic browsing, which concerns how to help users understand and explore the problem domain.

A Model-Driven Approach of Ontological Components for On-line Semantic Web Information Retrieval  (pp309-336)
        H. Baazaoui Zghal, M. A. Aufaure and N. Ben Mustapha
With the development of the web engineering and the advent of the semantic Web, adding a semantic dimension to the Web by the deployment of ontologies has contribute to solve many problems, which specify the knowledge shared by a community of a target domain in an explicit and formal way. The present work deals with the problem of ontology construction for the semantic Web. The objective of the paper is to propose a solution for the representation of Web knowledge by means of ontologies as well as to define an approach to their semi-automatic construction. The implementation and the experimentation of the proposition were achieved by the development of a framework, called "OntoCoSemWeb" and an On-Line Information Retrieval tool using the generated ontologies. An evaluation and an analysis of the results of this approach were carried out.

VQL - the Query Language for Semantically Information Retrieval in the SemanticLIFE Digital Memory Framework (pp337-359)
        H.H. Hoang and A M. Tjoa
This paper presents an approach of supporting users in formulating queries in the Semantic Web applications. We create an innovative mediator environment containing a lighter query language to help the users in the challenging task of making unambiguous requests. The query language is designed firstly for the SemanticLIFE's Virtual Query System~\cite{hanh2006d,hanh2006} and could be used for other semantic web applications. The proposed query language, namely Virtual Query Language (VQL), is an effort of reducing complexity in the query formulation, especially from the user-side. Furthermore, it simplifies the communication between components of the SemanticLIFE system with the VQS, and increases the portability of the system.

A Cluster-Based Approach to Web Adaptation in Context-Aware Applications (pp360-388)
        R. De Virgilio, R. Torlone, D. Valeriano, and D. Di Federico
In mobile Web applications, there is the need to take into account context characteristics (such as the device capabilities, the network QoS, the user preferences, and the location) to meet constraints of the client and guarantee a satisfying interaction with the user. A major issue in this framework is that, in real world scenarios, the number of adaptation requirements can change and increase very rapidly. Therefore, a relevant problem is the definition of effective methods for choosing efficiently the most suitable adaptation for a given context. To this aim, we propose in this paper a new cluster-based approach that automatically classifies the the contexts on the basis of their characteristics: at a logical level, each class corresponds to contexts that require similar adaptations. We show that this classification strongly alleviates the adaptation process. The approach relies on a metric distance that is used to compare contexts and on a threshold that is used to group them. Each context in a cluster is associated with the adaptation that best matches with the context requirements. We also illustrate an implementation of our approach and a number of experimental results that support its effectiveness. Semantic Web design principles and enabling technologies are important ingredients of the overall framework.

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