Context Dissemination in Peer-to-Peer Networks

Context Dissemination in Peer-to-Peer Networks

Antje Barth (University of Tübingen, Germany), Michael Kleis (Fraunhofer FOKUS, Germany), Andreas Klenk (Technische Universität München, Germany), Benoit Radier (France Télécom R&D, France), Sanaa Elmoumouhi (France Télécom R&D, France), Georg Carle (Technische Universität München, Germany) and Mikael Salaun (France Télécom R&D, France)
DOI: 10.4018/978-1-61520-973-6.ch005


In recent years, peer-to-peer overlay networks have become a popular communication paradigm with the potential to further change communication fundamentally in the future. Overlays allow communication abstraction but suffer from one inherent problem: The overlay is unaware of the context of a service or the context of a service consumer. The concept of context-awareness emerged out of the research done within the area of ubiquitous computing. Context-aware computing is one key technology to enable services and applications in the communication environment to adapt their behaviour based on the knowledge of environmental (contextual) information, thereby enhancing the system’s ability to become ever more responsive to the needs of the end-user or application domain. In this chapter we first introduce context and context architectures in general. In the remainder of the chapter we focus on the question: How can highly distributed context information be located and retrieved regarding small-scale as well as large-scale networks, addressing the topics of inter-domain management and scalability of context architectures?
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This section will introduce the fundamentals and basic concepts of context and context-aware computing by giving definitions and by briefly outlining the history of this computing paradigm. Afterwards, the main concepts of context modeling, context sensing and context monitoring will be explained. In recent history, much attention has been devoted to the terms context and context-awareness in the area of ubiquitous computing, leading to a great variety of definitions and interpretations depending on the respective application scenario.

What is Context?

An early definition of the term context in scientific work emerged in (Schilit, Adams and Want (1994)). The authors refer to context as „location, identities of nearby people and objects, and changes to those objects.“ This definition is not generic as it defines the term only by providing a set of examples. The authors in (Abowd, Dey, Brown, Davies, Smith and Steggles, P. (1999)) define context as „any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves.“ This definition is widely used within the area of ubiquitous computing at present.

In this chapter, however, context will be defined more generally as: “Any information that can be used to characterize the situation of an entity”. Entity refers to something that has a separate and distinct existence and objective, and situation is defined as a combination of circumstances and interactions at a given moment.

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