M. Wegdam

Supporting context-aware mobile applications: an infrastructure approach

Mobile phones and PDAs are converging into mobile lifestyle devices that offer a wide range of applications to end users. Many of these applications will have the ability to adapt themselves to the users situation, commonly referred to as context awareness. We argue that an infrastructure is needed to enable wide deployment of context-aware applications. A major benefit is interoperability between heterogeneous context sources and applications in a privacy-sensitive way. We identify three main technical challenges to realize such an infrastructure: reasoning to infer higher-level and better quality context information; efficient exchange and distributed processing of context information in dynamic and pervasive environments; and end-user-controlled handling of the privacy aspects. This article explains how we address these challenges with regard to the realization of an infrastructure that supports context-aware mobile applications. We use this infrastructure to support several mobile healthcare applications

Middleware Support for Quality of Context in Pervasive Context-Aware Systems

Middleware support for pervasive context-aware systems relieves context-aware applications from dealing with the complexity of context-specific operations such as context acquisition, aggregation, reasoning and distribution. The middleware decouples applications from the underlying heterogeneous context sensors, and offers advantages such as rapid development of context-aware applications and efficient usage of the context sensors. Context sensors have inherent limitations with respect to the quality of the context information they produce. Without breaking the decoupling, the middleware needs to explicitly model and quantify this quality of context in order to allow application to adapt their behavior based on the quality of context, for efficiency reasons and to enable quality-of-context-aware privacy policies. In this paper we identify and define five quality-of-context indicators for context-aware middleware, and discuss different alternatives for their quantification. These quality-of-context indicators are: precision, freshness, spatial resolution, temporal resolution and probability of correctness

Trustworthiness and Quality of Context Information

Context-aware service platforms use context information to customize their services to the current users situation. Due to technical limitations in sensors and context reasoning algorithms, context information does not always represent accurately the reality, and Quality of Context (QoC) models have been proposed to quantify this inaccuracy. The problems we have identified with existing QoC models is that they do not follow a standard terminology and none of them clearly differentiate quality attributes related to instances of context information (e.g. accuracy and precision) from trustworthiness, which is a quality attribute related to the context information provider. In this paper we propose a QoC model and management architecture that supports the management of QoC trustworthiness and also contributes to the terminology alignment of existing QoC models. In our QoC model, trustworthiness is a measurement of the reliability of a context information provider to provide context information about a specific entity according to a certain quality level. This trustworthiness value is used in our QoC management architecture to support context-aware service providers in the selection of trustworthy context providers. As a proof of concept to demonstrate the feasibility of our work we show a prototype implementation of our QoC model and management architecture.

Trust management model and architecture for context-aware service platforms

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.

An Information Model and Architecture for Context-Aware Management Domains

Context-aware service platforms use context-aware policy management solutions to manage users privacy preferences, to manage trust relationships, and to control access to the platform resources. However, existing context-aware policy management solutions focus on at most one policy management area (e.g. trust management, or privacy, or access control) and are difficult to integrate due to their unrelated policy/context information models and semantics. This leads to an integration problem, and to a policy management nightmare, because context-aware policies of different management areas have to be managed using different tools. In this paper, we address this problem using a new context-aware policy management abstraction called context-aware management domains (CAMDs). CAMDs allow the grouping of entities, for which a common set of policies apply, based on the entities context. In comparison to existing solutions CAMDs provide a more generic context-aware policy management abstraction. CAMDs are suitable for any policy management area, and allow context-aware obligation policies, which are not supported by existing policy management solutions.

Platform-independent dynamic reconfiguration of distributed applications

The aim of dynamic reconfiguration is to allow a system to evolve incrementally from one configuration to another at run-time, without restarting it or taking it offline. In recent years, support for transparent dynamic reconfiguration has been added to middleware platforms, shifting the complexity required to enable dynamic reconfiguration to the supporting infrastructure. These approaches to dynamic reconfiguration are mostly platform-specific and depend on particular implementation approaches suitable for particular platforms. In this paper, we propose an approach to dynamic reconfiguration of distributed applications that is suitable for application implemented on top of different platforms. This approach supports a platform-independent view of an application that profits from reconfiguration transparency. In this view, requirements on the ability to reconfigure components are expressed in an abstract manner. These requirements are then satisfied by platform-specific realizations.

Context-Aware trust domains

Context-aware service platforms need to establish and manage trust relationships for users to know if the users privacy policies are being enforced and for service providers to control access to their services. Current trust solutions are not suitable for this because they do not address in an integrated manner trust issues related to identity provisioning, privacy enforcement and context information trustworthiness. In addition, due to their hierarchical and centralized design, current trust management solutions do not scale well in the ad-hoc pervasive environments in which context-aware platforms are typically deployed. In this paper we propose context-aware trust domains as a management solution for context-aware service platforms.

Smart Sensing and Contex, First European Conference, EuroSSC 2006

Intelligent Sensors and Sensor Network.- Multi-channel Support for Dense Wireless Sensor Networking.- Data Aggregation for Target Tracking in Wireless Sensor Networks.- A Zone-Based Clustering Method for Ubiquitous Robots Based on Wireless Sensor Networks.- Context Awareness and Architectures.- A Simulation Study of Integrated Service Discovery.- Context Dissemination and Aggregation for Ambient Networks: Jini Based Prototype.- Discovery and Composition of Services for Context-Aware Systems.- Infrastructural Support for Dynamic Context Bindings.- Adding Context Awareness to C#.- Toward Wide Area Interaction with Ubiquitous Computing Environments.- Maintaining a World Model in a Location-Aware Smart Space.- Privacy, Application and Test Beds.- Shadow: A Middleware in Pervasive Computing Environment for User Controllable Privacy Protection.- Auditing and Inference Control for Privacy Preservation in Uncertain Environments.- Developing a Context-Aware System for Providing Intelligent Robot Services.- Music for My Mood: A Music Recommendation System Based on Context Reasoning.- WLAN Location-Aware Application Based on Accumulated Orientation Strength Algorithm.- Posters: Short Papers.- Context Delivery in Ad Hoc Networks Using Enhanced Gossiping Algorithms.- An Attribute-Based Naming Architecture for Wireless Sensor Networks Using a Virtual Counterpart Overlay Network.- A Sensor Platform for Sentient Transportation Research.- Attention-Based Information Composition for Multicontext-Aware Recommendation in Ubiquitous Computing.- Context-Aware Trust Domains.- An Evaluation Framework for Disseminating Context Information with Gossiping.- Dynamic Bayesian Networks for Visual Surveillance with Distributed Cameras.- Embedded Intelligence: Enabling In-Situ Power Management for Wireless Sensor Networks.- Proximity Sensing Using IEEE 802.15.4 Radios.- Towards Hovering Information.- Balancing Smartness and Privacy for the Ambient Intelligence.- Energy Conservation with EDFI Scheduling.- RuleCaster: A Programming System for Wireless Sensor Networks.- Losing Control in Pro-active Home Environments.This volume contains the papers and posters selected for presentation at the First European Conference on Smart Sensing and Context (EuroSSC 2006) in Enschede, The Netherlands. EuroSSC 2006 was the first conference of a series aiming at bringing together designers, engineers and researchers to explore two complementary viewpoints: – A device-centric, technology-driven view: concerning intelligent sensors, sensor networks and information processing for a new generation of networked devices and environments. – A service-centric, user-driven view: exploring architectures, techniques, and algorithms for context-aware and pro-active applications made possible by the diffusion of ambient communication, cooperating objects, and interaction technologies. These subjects are active and relevant research areas in themselves, and there are several conferences that address them separately. EuroSSC 2006, however, considered them both, and especially the symbiosis between them, which we expect to result in very inspiring and interesting discussions, as well as new research ideas on how to combine them. The conference was organized in single tracks covering various issues ranging from intelligent sensors, sensor networks, context management and context awareness, and privacy, to applications and test beds. Organizing a conference for the first time requires lots of preparations, such as finding a publisher, sponsoring organizations, and TPC members and most importantly attracting potential submitters. Fortunately, the amount and quality of the submissions were such that we were in the luxurious position to be able to accept only high quality and relevant papers. The conference attracted world wide attention and submissions came from five continents. A total of 15 accepted full papers and 14 accepted posters came from Asia, North America and Europe.