Physical widgets or phidgets are to physical user interfaces what widgets are to graphical user interfaces. Similar to widgets, phidgets abstract and package input and output devices: they hide implementation and construction details, they expose functionality through a well-defined API, and they have an (optional) on-screen interactive interface for displaying and controlling device state. Unlike widgets, phidgets also require: a connection manager to track how devices appear on-line; a way to link a software phidget with its physical counterpart; and a simulation mode to allow the programmer to develop, debug and test a physical interface even when no physical device is present. Our evaluation shows that everyday programmers using phidgets can rapidly develop physical interfaces.

The emergence of ubiquitous computing as a new design paradigm poses significant challenges for HCI and interaction design. Traditionally, human-computer interaction has taken place within a constrained and well-understood domain of experience – single users sitting at desks and interacting with conventionally-designed computers employing screens, keyboards and mice for interaction. New opportunities have engendered considerable interest in “context-aware computing” – computational systems that can sense and respond to aspects of the settings in which they are used. However, considerable confusion surrounds the notion of “context” – what it means, what it includes, and what role it plays in interactive systems. This paper suggests that the representational stance implied by conventional interpretations of “context” misinterprets the role of context in everyday human activity, and proposes an alternative model that suggests different directions for design.

Privacy is the most often-cited criticism of ubiquitous computing, and may be the greatest barrier to its long-term success. However, developers currently have little support in designing software architectures and in creating interactions that are effective in helping end-users manage their privacy. To address this problem, we present Confab, a toolkit for facilitating the development of privacy-sensitive ubiquitous computing applications. The requirements for Confab were gathered through an analysis of privacy needs for both end-users and application developers. Confab provides basic support for building ubiquitous computing applications, providing a framework as well as several customizable privacy mechanisms. Confab also comes with extensions for managing location privacy. Combined, these features allow application developers and end-users to support a spectrum of trust levels and privacy needs.

. In this paper, we propose ICrafter, a framework for services

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.

This paper borrows ideas from social science to inform the design of novel "sensing" user-interfaces for computing technology. Specifically, we present five design challenges inspired by analysis of human-human communication that are mundanely addressed by traditional graphical user interface designs (GUIs). Although classic GUI conventions allow us to finesse these questions, recent research into innovative interaction techniques such as `Ubiquitous Computing' and `Tangible Interfaces' has begun to expose the interaction challenges and problems they pose. By making them explicit we open a discourse on how an approach similar to that used by social scientists in studying human-human interaction might inform the design of novel interaction mechanisms that can be used to handle human-computer communication accomplishments.

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Tangible user interfaces (TUIs) augment the physical world by integrating digital information with everyday physical objects. Currently, building these UIs requires “getting down and dirty ” with input technologies such as computer vision. Consequently, only a small cadre of technology experts can currently build these UIs. Based on a literature review and structured interviews with nine TUI researchers, we created Papier-Mâché, a toolkit for building tangible interfaces using computer vision, electronic tags, and barcodes. Papier-Mâché introduces a high-level event model for working with these technologies that facilitates technology portability. For example, an application can be prototyped with computer vision and deployed with RFID. We present an evaluation of our toolkit with six class projects and a user study with seven programmers, finding the input abstractions, technology portability, and monitoring window to be highly effective.

In this paper we propose an OWL encoded context ontology (CONON) for modeling context in pervasive computing environments, and for supporting logicbased context reasoning. CONON provides an upper context ontology that captures general concepts about basic context, and also provides extensibility for adding domain-specific ontology in a hierarchical manner. Based on this context ontology, we have studied the use of logic reasoning to check the consistency of context information, and to reason over low-level, explicit context to derive high-level, implicit context. By giving a performance study for our prototype, we quantitatively evaluate the feasibility of logic based context reasoning for nontime-critical applications in pervasive computing environments, where we always have to deal carefully with the limitation of computational resources. 1.

This essay considers the problem of defining the context that context aware systems should pay attention to from a human perspective. In particular, we argue that there are human aspects of context that cannot be sensed or even inferred by technological means, so context aware systems cannot be designed simply to act on our behalf. Rather they will have to be able to defer to users in an efficient and non-obtrusive fashion. Our point is particularly relevant for systems that are constructed such that applications are architecturally isolated from the sensing and inferencing that governs their behavior. We propose a design framework that is intended to guide thinking about accommodating human aspects of context. This framework presents four design principles that support intelligibility of system behavior and accountability of human users and a number of human-salient details of context that must be accounted for in context aware system design.