We introduce the provisional trust negotiation framework PROTUNE, for combining distributed trust management policies with provisional-style business rules and accesscontrol related actions. The framework features a powerful declarative metalanguage for driving some critical negotiation decisions, and integrity constraints for monitoring negotiations and credential disclosure.

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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.