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 3 main problems: (a) the notion of context is still ill defined, (b) there is a lack of conceptual models and methods to help drive the design of context-aware applications, and (c) no tools are available to jump-start the development of context-aware applications. In this anchor article, we address these 3 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 context-aware 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 context-aware applications that have been prototyped using the Context Toolkit. We also demonstrate how such a framework can support the investigation of important research challenges in the area of context-aware computing.

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A conceptual framework and a toolkit for supporting the rapid prototyping of context-aware applications

Mobile phones or smartphones are rapidly becoming the central computer and communication device in people's lives. Application delivery channels such as the Apple AppStore are transforming mobile phones into App Phones, capable of downloading a myriad of applications in an instant. Importantly, today's smartphones are programmable and come with a growing set of cheap powerful embedded sensors, such as an accelerometer, digital compass, gyroscope, GPS, microphone, and camera, which are enabling the emergence of personal, group, and communityscale sensing applications. We believe that sensor-equipped mobile phones will revolutionize many sectors of our economy, including business, healthcare, social networks, environmental monitoring, and transportation. In this article we survey existing mobile phone sensing algorithms, applications, and systems. We discuss the emerging sensing paradigms, and formulate an architectural framework for discussing a number of the open issues and challenges emerging in the new area of mobile phone sensing research.

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A survey of mobile phone sensing

Context-aware computing is a mobile computing paradigm in which applications can discover and take advantage of contextual information (such as user location, time of day, nearby people and devices, and user activity) Since it was proposed about a decade ago, many researchers have studied this topic and built several context-aware applications to demonstrate the usefulness of this new technology Context-aware applications (or the system infrastructure to support them), however, have never been widely available to everyday users In this survey of research on context-aware systems and applications, we looked in depth at the types of context used and models of context information, at systems that support collecting and disseminating context, and at applications that adapt to the changing context Through this survey, it is clear that context-aware research is an old but rich area for research The difficulties and possible solutions we outline serve as guidance for researchers hoping to make context-aware computing a reality

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A Survey of Context-Aware Mobile Computing Research

A survey of context modelling and reasoning techniques

Traditional interactive applications are limited to using only the input that users explicitly provide. As users move away from traditional desktop computing environments and move towards mobile and ubiquitous computing environments, there is a greater need for applications to leverage from implicit information, or context. These types of environments are rich in context, with users and devices moving around and computational services becoming available or disappearing over time. This information is usually not available to applications but can be useful in adapting the way in which it performs its services and in changing the available services. Applications that use context are known as context-aware applications. 
This research in context-aware computing has focused on the development of a software architecture to support the building of context-aware applications. While developers have been able to build context-aware applications, they have been limited to using a small variety of sensors that provide only simple context such as identity and location. This dissertation presents a set of requirements and component abstractions for a conceptual supporting framework. The framework along with an identified design process makes it easier to acquire and deliver context to applications, and in turn, build more complex context-aware applications. 
In addition, an implementation of the framework called the Context Toolkit is discussed, along with a number of context-aware applications that have been built with it. The applications illustrate how the toolkit is used in practice and allows an exploration of the design space of context-aware computing. This dissertation also shows how the Context Toolkit has been used as a research testbed, supporting the investigation of difficult problems in context-aware computing such as the building of high-level programming abstractions, dealing with ambiguous or inaccurate context data and controlling access to personal context.

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Providing architectural support for building context-aware applications

Mobile information appliances are increasingly used in numerous different situations and locations, setting new requirements to their interaction methods When the user's situation, place or activity changes, the functionality of the device should adapt to these changes In this work we propose a layered real-time architecture for this kind of context-aware adaptation based on redundant collections of low-level sensors Two kinds of sensors are distinguished: physical and logical sensors, which give cues from environment parameters and host information A prototype board that consists of eight sensors was built for experimentation The contexts are derived from cues using real-time recognition software, which was constructed after experiments with Kohonen's Self-Organizing Maps and its variants A personal digital assistant (PDA) and a mobile phone were used with the prototype to demonstrate situational awareness On the PDA font size and backlight were changed depending on the demonstrated contexts while in mobile phone the active user profile was changed The experiments have shown that it is feasible to recognize contexts using sensors and that context information can be used to create new interaction metaphors

Advanced Interaction in Context

TheCommonKADS Expertise Modeling Library is the result of work that started as a further development of the KADS Library of interpretation models (Breukeret al., 1987). It incorporates new views and experiences of the knowledge acquisition community on the reuse of problem-solving components, in particular problem-solving methods and their assumptions on domain knowledge. Its design allows to store and index an extensible set of modeling components of different levels of granularity, as well as generic (partial) models of expertise and even reusable modeling steps. Further, its contents were significantly expanded, in what is probably the largest library of problem solving methods presently. In this article, we explain the rationale of the design of theCommonKADS library, the mechanisms defined to index the elements it stores, and the Library contents. An example of the use of a part of the Library concerned with problem-solving methods for assessment tasks is presented. The Library is not a finished product: not only because still many contents may need further verification and validation, but also because the Library is intended to accumulate and share practical experiences and advice on the process of modeling for actual applications. These and other shortcomings and lessons are discussed.

TheCommonKADS library in perspective

The situations in which human-computer interaction takes place are increasingly varied, as computers become highly portable and embedded in everyday environments. Research reported from different communities (Wearable Computing, Mobile Computing, HCI, CSCW, Augmented Reality) indicates that awareness of situations can lead to improvement of human-computer interaction. We propose a workshop at CHI2000 to provide a forum to discuss situational awareness and situated interaction.With the availability of sensing technologies, such as measuring the surrounding light conditions, the motion of the user, the orientation of a display, users' position relative to an information appliance, the number of users in front of a device, users' emotional state (bio-sensors), etc., this situational context can be captured and used as additional input to the system. The interaction process can benefit from the additional knowledge about the situation [1].

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Situated interaction in ubiquitous computing

This (position)paper claims that the role of Natural Language in a hyper-media information system is to provide, at each moment, a context-sensitive navigation point, ie, a hypertext node in which the relevance of hyperlinks is justified with respect to the context of the interaction It acts as the primary entry point for the user to the various pages that constitute an information service We call context the collection of features that determine the desirable content and form of the information We describe an experiment based on an existing information server showing how to capture contextual parameters and how to render them in a contextsensitive entry point to information The key to our approach is a model of competition for attention between software agents, the outcome of which is reflected in a weighted topic structure, annotated with text templates The annotated topic structure is the basis for generating a context-sensitive navigation node by a process of template expansion and aggregation humanized interfaces and intelligent agents that act as personalised and adaptive assistants to the user The underlying assumption is that contextual parameters must influence information provision Context includes static models and highly dynamic parameters Our research fits in a broader picture of what will be the future networks We think of it as turning the network inside-out: rather than having users looking for information, we think of it as a huge collection of agents (encapsulating information and services) looking for users In a nutshell we emphasize that the user’s attention is limited and that agents must compete for this attention, based on how they judge themselves relevant and competent to interact with that user in the context that this one finds herself in This paper claims that the role of Natural Language in a hyper-media information system is to provide, at each moment, a context for relevant information Natural language is ideally suited to communicate in a compact form the reason why a particular information page is likely to be useful to the user in the context she finds herself in It can also express a variety of balances between topics and uses, sensitive to the various contextual dimensions

https://aaaipress.org/Papers/Symposia/Spring/1997/SS-97-02/SS97-02-007.pdf

Context-sensitive hypertext generation

The work presented in this paper focuses on software tools that act as video explorers and annotation platforms and more specifically as diary composers for younger children. Through such tools, children can have as their raw material video recordings from everyday life and they are given the opportunity to review this material, reflect upon it and annotate it, thus creating the stories of everyday life from their own perspective. The specific tool proposed, focuses on multiperspective capture of events by one or more children and their cooperation during the annotation procedure.

Walter Van de Velde

Papers

Advanced Interaction in Context

TheCommonKADS library in perspective

Situated interaction in ubiquitous computing

Context-sensitive hypertext generation

Using Multimedia to Support Reflection on Past Events for Young Children