Ontology Based Context-Aware Adaptation Approach

Pervasive information systems aim to make information available anywhere and at anytime. These systems should be used in different contexts depending on the environment of the user, her/his profile and her/his device. Consequently, one of the main problems of such information systems is the adaptation to context. In this chapter, the authors propose a comprehensive and open strategy that guarantees the adaptation of applications to context on three facets: (i) the services offered to the user, (ii) the multimedia contents returned by these services, and (iii) their presentation to the user. Service adaptation consists of modules that intercept the application’s service calls and modify their behavior using a list of functional adaptation operators. Data adaptation consists in transforming or replacing the non-usable multimedia service outputs in the considered context situation. Presentation adaptation consists in automatically generating the complete code of the user interface that guarantees the interaction with the adapted data and services. The authors’ adaptation strategy has achieved two goals: (i) incrementally integrate context awareness in the application and (ii) guarantee the adaptation starting from a simple description of the services offered to the user. They have validated this strategy by developing a platform that guarantees applications adaptation to context. They used Java, OSGi and Web service technologies to implement this platform. They have also successfully tested our adaptation approach on a home healthcare application concerning dialyzed persons.

Kindergarten

Mobile context-aware applications have specific needs regarding data communications and position sensing, that current standard hardware is still not able to fulfill. Current mechanisms are inadequate for applications that need constant communications because of their high power needs and low precision when used to measure the physical indoor position of a mobile device. For this reason the authors have created a new, flexible and inexpensive technology that aims to solve both the needs of communication and position estimation on mobile platforms. This new network type uses recently developed technology to minimize power consumption, leading to a longer battery life and maximizing the precision of the position sensing of the device. Finally, on top of their hardware platform they have devised a software layer, named Kindergarten, which allows high-level languages to interact with the underlying hardware.

Context-Aware Database Querying

Context is an essential element in mobile and ubiquitous computing. Users’ information needs can be better understood and supplied by means of context-awareness. Context data may be sensed, inferred, or directly input by users, and so forth, which calls for specific query mechanisms to acquire context information. On the other hand, traditional non-context-aware database querying techniques need to be re-examined, taking query context into account. In order to design effective context-aware database query processing mechanism, the authors survey the latest developed context-aware querying techniques in the data management field. They outline six ways to query context directly, and provide a categorization about how to use context in querying traditional databases. The approaches of handling imperfect context in context-aware database querying are also described. They discuss some potential research issues to be addressed at the end of the chapter.

Incorporating Human Factors in the Development of Context-Aware Personalized Applications

The notion of context in context-aware applications is not merely an issue of external situational circumstances or device/channel properties, but it could also refer to a wide array of user characteristics that have an effect throughout users’ interactions with a system. Human factors such as cognitive traits and current state, from a psychological point of view, are undoubtedly significant in the shaping of the perceived and objective quality of interactions with a system, and by defining context in that sense, personalization may as well become an essential function of context aware applications. The research characterthat is presented in this chapter focuses on identifying human factors that relate to users’ performance in Web applications that involve information processing, and a framework of personalization rules that are expected to increase users’ performance is depicted. The environments that empirical results were derived from were both learning and commercial; in the case of E-Learning personaliza tion was beneficial, while the interaction with a commercial site needs to be further investigated due to the implicit character of information processing in the Web.

Access Control in Mobile and Ubiquitous Environments

Access control is the process of granting permissions in accordance to an authorization policy. Mobile and ubiquitous environments challenge classical access control solutions like Role-Based Access Control. The use of context-information during policy definition and access control enforcement offers more adaptability and flexibility needed for these environments. When it comes to low-power devices, such as wireless sensor networks, access control enforcement is normally too heavy for such resourceconstrained devices. Lightweight cryptography allows encrypting the data right from its production and the access is therefore intrinsically restricted. In addition, all access control mechanisms require an authenticated user. Traditionally, user authentication is performed by means of a combination of authentication factors, statically specified in the access control policy of the authorization service. Within ubiquitous and mobile environment, there is a clear need for a flexible user authentication using the available authentication factors. In this chapter, different new techniques to ensure access control are discussed and compared to the state-of-the-art.

Adaptive Resource and Service Management in a Mobile-Enabled Environment

Due to its nature, a mobile-enabled environment is very dynamic: reachable resources and services change very often. Users hardly know which resources they can exploit and which services they may require. In such a context, a technical support which identifies the available resources and services and indicates which resource is the best one to execute a service would be very helpful. This chapter proposes an adaptive solution to achieve these issues. Adaptivity is related to the fact that besides searching for the reachable resources or services, this approach proposes the most appropriate one for the current request by exploiting additional information about users, resources and services. Moreover, it ensures that services are delivered with the qualities requested and expected by the users. In the scientific literature adaptivity is exploited for functionality reasons (i.e., a system is not able to do what it was supposed to do) or for performance reasons (i.e., a system is not able to ensure the qualities of the services expected by the users or there is a better configuration for a given task). A challenging issue of adaptivity is the identification and design of the knowledge useful for the adaptation process and how this knowledge is exploited at run-time especially in a highly dynamic environment. This chapter proposes an approach which models the adaptation knowledge through reflective entities, qualities and properties, the management of the adaptation knowledge through views, the decision support through strategies, and the management of the functional and non-functional elements through managers.

An Evaluation of Context-Aware Infomobility Systems

The delivery of real-time, context-aware, and personalized information to end-users for mobility support is a high-priority objective in improving mobility services efficiency and effectiveness. This chapter aims at providing an analysis of existing studies in the field of context awareness research targeted to the infomobility application domain. The authors propose an evaluation framework for infomobility services based on the elicitation of context information items and high-level requirements. The framework is applied to some relevant state-of-the art research works among personal navigation systems, infomobility service integration frameworks and context-aware location-based communication platforms. Evaluation results are discussed in order to highlight open research challenges in the infomobility application domain.

Employing Context Information and Semantics to Advance Responsiveness in Service Composition

The idea of context-aware services has been around for a long time. The rise of user mobility enabled by well-equipped mobile devices, increasing interconnectedness and available service platforms such as the mobile Web offers new possibilities for context-aware computing, but, at the same time, produces a number of novel challenges. In this chapter, the authors observe current approaches in this active research area, and identify the respective challenges, achievements, and trends. The authors also extend the notion of context-aware services by considering service composition approaches, and present a middleware aiming at the autonomic and context-aware provision of services in mobile peer-to-peer networks. In this regard special attention is paid to a semantic blackboard concept to cache and disseminate context data and a context-aware service composition approach in terms of the identified trends and challenges.

Distributed Context Management in Support of Multiple Remote Users

In ubiquitous computing environments, context management systems are expected to administrate large volumes of spatial and non-spatial information in geographical disperse domains. In particular, when these systems cover wide areas such as cities, countries or even the entire planet, the design of scalable storage, retrieval and propagation mechanisms is paramount. This chapter elaborates on mechanisms that address advanced requirements including support for distributed context databases management; efficient query handling; innovative management of mobile physical objects and optimization strategies for distributed context data dissemination. These mechanisms establish a robust spatially-enhanced distributed context management framework that has thoroughly been designed, carefully implemented and extensively evaluated via numerous experiments.

Privacy Automation in Context-Aware Services

With the growing interest in context-aware services, attention has been given to privacy and trust issues. Context-aware privacy architectures are usually proposed and developed without taking into account the trustworthiness of a service provider. Therefore, this chapter deals with two challenges in context-aware services. The first one is to improve privacy architectures with a trust functionality and the second one is to integrate this refined privacy architecture in larger service-oriented architectures (SOAs).