Computing devices and applications are now used beyond the desktop, in diverse environments, and this trend toward ubiquitous computing is accelerating. One challenge that remains in this emerging research field is the ability to enhance the behavior of any application by informing it of the context of its use. By context, we refer to any information that characterizes a situation related to the interaction between humans, applications and the surrounding environment. Context-aware applications promise richer and easier interaction, but the current state of research in this field is still far removed from that vision. This is due to three main problems: (1) the notion of context is still ill defined; (2) there is a lack of conceptual models and methods to help drive the design of context-aware applications; and (3) no tools are available to jump-start the development of context-aware applications. In this paper, we address these three problems in turn. We first define context, identify categories of contextual information, and characterize context-aware application behavior. Though the full impact of context-aware computing requires understanding very subtle and high-level notions of context, we are focusing our efforts on the pieces of context that can be inferred automatically from sensors in a physical environment. We then present a conceptual framework that separates the acquisition and representation of context from the delivery and reaction to context by a contextaware application. We have built a toolkit, the Context Toolkit, that instantiates this conceptual framework and supports the rapid development of a rich space of context-aware applications. We illustrate the usefulness of the conceptual framework by describing a number of contextaware applications that h...

Abstract. The use of context is important in interactive applications. It is particularly important for applications where the user’s context is changing rapidly, such as in both handheld and ubiquitous computing. In order to better understand how we can use context and facilitate the building of context-aware applications, we need to more fully understand what constitutes a contextaware application and what context is. Towards this goal, we have surveyed existing work in context-aware computing. In this paper, we provide an overview of the results of this survey and, in particular, definitions and categories of context and context-aware. We conclude with recommendations for how this better understanding of context inform a framework for the development of context-aware applications. 1

Context-aware systems offer entirely new opportunities for application developers and for end users by gathering context data and adapting systems behavior accordingly. Especially in combination with mobile devices these mechanisms are of high value and are used to increase usability tremendously. In this pap er, we present common architecture principles of context-aware systems and derive a layered conceptual design framework to explain the different elements common to most context-aware architectures. Based on these design principles, we introduce various existing context-aware systems focusing on context-aware middleware and frameworks, which ease the development of context-aware applications. We discuss various approaches and analyze important aspects in context-aware computing on the basis of the presented systems.

Mobile guides and navigational assistants have come a long way since the first research prototypes (e.g. [1]). At the moment, there are not only many different research projects working on the topic (some of which we will present in this chapter), but there are also several commercial services available to mobile phone

Capturing, defining, and modeling the essence of context are challenging, compelling, and prominent issues for interdisciplinary research and discussion. The roots of its emergence lie in the inconsistencies and ambivalent definitions across and within different research specializations (e.g., philosophy, psychology, pragmatics, linguistics, computer science, and artificial intelligence). Within the area of computer science, the advent of mobile context-aware computing has stimulated broad and contrasting interpretations due to the shift from traditional static desktop computing to heterogeneous mobile environments. This transition poses many challenging, complex, and largely unanswered research issues relating to contextual interactions and usability. To address those issues, many researchers strongly encourage a multidisciplinary approach. The primary aim of this article is to review and unify theories of context within linguistics, computer science, and psychology. Summary models within each discipline are used to propose an outline and detailed multidisciplinary model of context involving (a) the HUMAN--COMPUTER INTERACTION, 2005, Volume 20, pp. 403--446 Copyright 2005, Lawrence Erlbaum Associates, Inc.

<E-213> Ubiquitous computing (ubicomp) is an emerging paradigm for interaction between people and computers. A<E-443> guiding principle of ubicomp is to break away from desktop computing to provide computational services<E-419> to a user when and where required. Although there has been a lot of experimental work in ubicomp, there<E-431> has been little effort to define an agenda in ubicomp for HCI researchers. In this paper, we attempt to<E-442> remedy that problem by defining the space of ubicomp applications in terms of the level of user mobility<E-415> and transparency of interaction. Increases in user mobility will come with technological advances, but<E-437> increased interaction transparency will come only with breakthroughs in HCI research. We conclude the<E-438> paper with a discussion of two functional themes that we have found important across a number of ubicomp<E-416> systems ---context-awareness and automated capture, integration and access. Each of these themes raises<E-...

In this paper we examine an emerging class of systems that link People-to-People-to-Geographical-Places; we call these P3-Systems. Through analyzing the literature, we have identified four major P3-System design techniques: People-Centered systems that use either absolute user location (e.g. Active Badge) or user proximity (e.g. Hocman) and Place-Centered systems based on either a representation of people’s use of physical spaces (e.g. ActiveMap) or on a matching virtual space that enables online interaction linked to physical location (e.g. Geonotes). In addition, each feature can be instantiated synchronously or asynchronously. The P3 framework organizes existing systems into meaningful categories and structures the design space for an interesting new class of context-aware systems. It also suggests additional challenges and opportunities.

Intelligent environments and cities have become a popular topic in recent literature. The island nation of Singapore has often been mentioned as an example of an intelligent city for its visionary IT2000 project where

Abstract. This paper develops a representation-theoretic notion of spatial context for cognitive agents that interact with spatial environments. We discuss the state of the art in defining context as used in context-aware and / or location-aware systems. In contrast to existing approaches, we define context through cognitive processes. Placing cognitive processes in the focus of our context definition allows for a truly user-centered perspective: conceptualizations imbue spatial structures with meaning. This allows for fixing terminological problems and relating context definitions to work in spatial information theory and cognitive science. Although we focus on spatial context, the approach is generic and can be adapted to other domains in which cognitive aspects concerning users of information systems are central. 1

Context Awareness is a relatively new research area that uses context information to improve the operation of applications. These applications are called `context aware'. However, there is no common understanding what context is, and how context can be used to improve the operation of applications. One of the problems that the developer of a context aware application must deal with, is the problem of obtaining context information. A context architecture should relieve the application developer of this problem: it must obtain context information and present it to applications. The objectives of this study are to define the concepts `context` and `context aware`, and to gain insight in how context aware applications use context, in order to determine the requirements of a context architecture.