Abstract

No abstract

Context-awareness refers to systems that unobtrusively adapt to the environment of their users on the basis of context information, popularly known as context-aware systems. One inherent property of context information is that it possesses a certain quality, such as the certainty with which it has been determined and so on. Different aspects of this quality are represented by a set of indicators collectively known as Quality of Context (QoC). QoC also represents privacy sensitiveness of context information, i.e. context information of higher quality is considered more privacy sensitive. An important step towards making QoC indicators usable is to quantify them in tangible units. In this paper we provide motivation for using QoC indicators as meta-information for context management and use QoC as part of a user privacy enforcement framework. We propose five QoC indicators and present different alternatives available for expressing them quantitatively.

Distributedsystems with high availability requirements have to support some form of dynamic reconfiguration. This means that they must provide the ability to be maintained or upgraded without being taken off-line. Building a distributed system that allows dynamic reconfiguration is very intrusive to the overall design of the system, and generally requires special skills from both the client and server side application developers. There is an opportunity to provide support for dynamic reconfiguration at the object middleware level of distributed systems, and create a dynamic reconfiguration transparency to application developers. In this paper, we propose a Dynamic Reconfiguration Service for CORBA that allows the reconfiguration of a running system with maximum transparency for both client and server side developers. We describe the architecture, a prototype implementation, and some preliminary test results.

The entities participating in a context-aware service platform need to establish and manage trust relationships in order to assert different trust aspects including identity provisioning, privacy enforcement, and context information provisioning. Current trust management models address these trust aspects individually when in fact they are dependent on each other. In this paper we identify and analyze the trust relationships in a context-aware service platform and propose an integrated trust management model that supports quantification of trust for different trust aspects. Our model addresses a set of trust aspects that is relevant for our target context-aware service platform and is extensible with other trust aspects. We propose to calculate a resulting trust value for contextaware services, which considers the dependencies between the different trust aspects, and aims to support the users in the selection of the more trustworthy services. In this calculation we target two types of user goals: one with high priority in privacy enforcement (privacy concerned) and one with high priority in the service adaptation (service concerned). Based on our trust model we have designed a distributed trust management architecture and implemented a proof of concept prototype.