Abstract. Semantic Web databases allow efficient storage and access to RDF statements. Applications are able to use expressive query languages in order to retrieve relevant metadata to perform different tasks. However, access to metadata may not be public to just any application or service. Instead, powerful and flexible mechanisms for protecting sets of RDF statements are required for many Semantic Web applications. Unfortunately, current RDF stores do not provide fine-grained protection. This paper fills this gap and presents a mechanism by which complex and expressive policies can be specified in order to protect access to metadata in multi-service environments.

Open distributed environments, such as the World Wide Web, facilitate information sharing but provide limited support to the protection of sensitive information and resources. Trust negotiation (TN) frameworks have been proposed as a better solution for open environments, in which parties may get in touch and interact without being previously known to each other. In this paper, we illustrate PROTUNE, a rule-based TN system. By describing PROTUNE, we will illustrate the advantages that arise from an advanced rule-based approach in terms of deployment efforts, user friendliness, communication efficiency, and interoperability. The generality and technological feasibility of PROTUNE's approach are assessed through an extensive analysis and experimental evaluations.

Abstract. Trust and policies are going to play a crucial role in enabling the potential of many web applications. Policies are a well-known approach to protecting security and privacy of users in the context of the Semantic Web: in the last years a number of policy languages were proposed to address different application scenarios.The first part of this chapter provides a broad overview of the research field by accounting for twelve relevant policy languages and comparing them on the strength of ten criteria which should be taken into account in designing every policy language. By comparing the choices designers made in addressing such criteria, useful conclusions can be drawn about strong points and weaknesses of each policy language.The second part of this chapter is devoted to the description of the Protune framework, a system for specifying and cooperatively enforcing security and privacy policies on the Semantic Web developed within the network of excellence REWERSE. We describe the framework's functionalities, provide details about their implementation, and report the results of performance evaluation experiments.

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Abstract:Modeling competences is an integral part of many Human Resource (HR) and e-Learning related activities. HR departments use competence descriptions to define requirements needed for performing specific tasks or jobs. The same competences are acquired by employees and applicants by e.g. experience or certifications. Typically, HR departments need to match such required and acquired competences in order to find suitable candidates. In e-Learning a similar situation arises. Curricula or training programmes need to describe prerequisites that must be fulfilled before joining and the competences that will be acquired after successful completion. This paper analyses the limitations and extends existing approaches for modeling competences in order to allow (semi-)automatic competence matching.