Distributed Context Management in Support of Multiple Remote Users

Distributed Context Management in Support of Multiple Remote Users

I. Roussaki (National Technical University of Athens, Greece), M. Strimpakou (National Technical University of Athens, Greece), C. Pils (Waterford Institute of Technology, Ireland), N. Kalatzis (National Technical University of Athens, Greece) and N. Liampotis (National Technical University of Athens, Greece)
DOI: 10.4018/978-1-60566-290-9.ch004
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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.
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1. Introduction

In the emerging and challenging ubiquitous computing environment mobile users will experience the successive enlargement and refinement of their computing and communication potential beyond their vision of the future world. They will wear smart clothes that will monitor their bio signals and act accordingly. They will carry personal communicators able to support highly complex task processing. They will hold advanced cards that will automatically handle their transactions. More sophisticated navigation and control systems will be embedded into the vehicles they drive. Invisible microcomputers and other artefacts will exist everywhere in their smart homes and offices to assist them in their every day lives. The collection all these heterogeneous computing devices will interact with intelligent sensors embedded in the surrounding environment in order to form an ambient-aware pervasive environment, which supports everyday activities related to business, education, leisure, healthcare, etc. In this respect, customers will be able to enjoy new experiences in a non-obtrusive way, as the existing infrastructure will become minimally intrusive and will exhibit inherent proactiveness and dynamic adaptability to current conditions, user preferences and environment. Eventually, as traditional systems evolve into pervasive, an important aspect that needs to be pursued is context-awareness (Xynogalas et al., 2004).

According to one of the most popular context definitions, context is basically all information that is relevant to a human-computer interaction (Dey, 2000). Theoretically, any information can become relevant for a certain task and thus, one can hardly derive context management requirements from this definition. In any case, the detection of the most important context information for characterizing the situation of a particular entity, irrespectively of the application domain, is best achieved by considering the following criterion: Human experience is strongly interrelated with location. We work when we are in our offices, we eat in a restaurant, we sleep at home, and we dance in a bar. This common understanding also influences the manner people interact with the various computing and communications systems and therefore, the way they perceive context-awareness. A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task, and therefore, implicitly, but no exclusively, on his location. In this respect, users are more interested in context information related to their current position. Until now, the design principles in context-aware systems are mainly limited in addressing special requirements and conditions of isolated areas (e.g. smart homes, offices, artifacts, etc.) in an ad-hoc manner (Strimpakou et al., 2006). Even though the progress on this field is quite impressive, few research initiatives have attempted to design and implement a general-purpose context management system, adequate for pervasive environments. Furthermore, there are very limited or even none research efforts that have dealt with minimizing the various costs introduced during the propagation of context information to multiple remote nodes maintaining replicas of master context instances, when a multitude of different context consumers residing on these remote nodes often requests for the respective replicated context information. The research presented in this chapter focuses on developing and validating the Context Distributed Database Management System (CDDBMS), an efficient distributed heterogeneous spatial database management system that adopts a location-centric context view, integrates sophisticated selective context replica update policies for cost minimisation and is adequate for addressing the high and continuously expanding context consumer demands anytime, anyplace in future pervasive environments.

The rest of this Chapter is structured as follows. Section 2 elaborates on the motivation for the presented research work, while Section 3 briefly describes the overall CDDBMS architecture and context query handling approach. Section 4 outlines the basic CDDBMS approach for managing mobile physical objects. The context data dissemination problem is described in Section 5, a heuristic solution of which is provided in Section 6. Section 7 analyses the conducted experiments and presents the obtained evaluation results. Finally, in Section 8, a comparison of the proposed approach with the relevant state of the art work is provided, while in Section 9, conclusions are drawn and future plans are exposed.

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Editorial Advisory Board
Table of Contents
Thomas Strang
Theo Kanter
Dragan Stojanovic
Dragan Stojanovic
Chapter 1
Davy Preuveneers, Koen Victor, Yves Vanrompay, Peter Rigole, Manuele Kirsch Pinheiro
In recent years, many researchers have studied context-awareness to support non-intrusive adaptability of context-aware applications. Context-aware... Sample PDF
Context-Aware Adaptation in an Ecology of Applications
Chapter 2
Tarak Chaari, Mohamed Zouari, Frédérique Laforest
Pervasive information systems aim to make information available anywhere and at anytime. These systems should be used in different contexts... Sample PDF
Ontology Based Context-Aware Adaptation Approach
Chapter 3
Florian Daniel
Adaptivity (the runtime adaptation to user profile data) and context-awareness (the runtime adaptation to generic context data) have been gaining... Sample PDF
Context-Aware Applications for the Web: A Model-Driven Development Approach
Chapter 4
I. Roussaki, M. Strimpakou, C. Pils, N. Kalatzis, N. Liampotis
In ubiquitous computing environments, context management systems are expected to administrate large volumes of spatial and non-spatial information... Sample PDF
Distributed Context Management in Support of Multiple Remote Users
Chapter 5
Jared Zebedee, Patrick Martin, Kirk Wilson, Wendy Powley
Pervasive computing presents an exciting realm where intelligent devices interact within the background of our environments to create a more... Sample PDF
An Adaptable Context Management Framework for Pervasive Computing
Chapter 6
Yuanping Li, Ling Feng, Lizhu Zhou
Context is an essential element in mobile and ubiquitous computing. Users’ information needs can be better understood and supplied by means of... Sample PDF
Context-Aware Database Querying: Recent Progress and Challenges
Chapter 7
Carsten Jacob, Heiko Pfeffer, Stephan Steglich
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... Sample PDF
Employing Context Information and Semantics to Advance Responsiveness in Service Composition
Chapter 8
Heinz-Josef Eikerling, Pietro Mazzoleni
The authors present a holistic approach for the efficient design, implementation, and validation of context-aware mobile services. The according... Sample PDF
A Methodology for the Design, Development and Validation of Adaptive and Context-Aware Mobile Services
Chapter 9
Stefan Dietze, Alessio Gugliotta, John Domingue
Context-awareness is highly desired, particularly in highly dynamic mobile environments. Semantic Web Services (SWS) address context-adaptation by... Sample PDF
Bridging the Gap between Mobile Application Contexts and Semantic Web Resources
Chapter 10
Claudia Raibulet
Due to its nature, a mobile-enabled environment is very dynamic: reachable resources and services change very often. Users hardly know which... Sample PDF
Adaptive Resource and Service Management in a Mobile-Enabled Environment
Chapter 11
Nahuel Lofeudo, Andrés Fortier, Gustavo Rossi
Mobile context-aware applications have specific needs regarding data communications and position sensing, that current standard hardware is still... Sample PDF
Kindergarten: A Novel Communication Mechanism for Mobile Context-Aware Applications
Chapter 12
Laurent Gomez, Annett Laube, Alessandro Sorniotti
Access control is the process of granting permissions in accordance to an authorization policy. Mobile and ubiquitous environments challenge... Sample PDF
Access Control in Mobile and Ubiquitous Environments
Chapter 13
Amr Ali Eldin, Semir Daskapan, Jan van den Berg
With the growing interest in context-aware services, attention has been given to privacy and trust issues. Context-aware privacy architectures are... Sample PDF
Privacy Automation in Context-Aware Services
Chapter 14
Adrien Joly, Pierre Maret, Fabien Bataille
These times, when the amount of information exponentially grows on the Internet, when most people can be connected at all times with powerful... Sample PDF
Leveraging Semantic Technologies towards Social Ambient Intelligence
Chapter 15
Federica Paganelli, Dino Giuli
The delivery of real-time, context-aware, and personalized information to end-users for mobility support is a high-priority objective in improving... Sample PDF
An Evaluation of Context-Aware Infomobility Systems
Chapter 16
Nikos Tsianos, Panagiotis Germanakos, Zacharias Lekkas, Constantinos Mourlas
The notion of context in context-aware applications is not merely an issue of external situational circumstances or device/channel properties, but... Sample PDF
Incorporating Human Factors in the Development of Context-Aware Personalized Applications: The Next Generation of Intelligent User Interfaces
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