Interactions in the style of the ubiquitous computing paradigm are possible today, but only in handcrafted environments within one administrative and technological realm. This thesis describes an architecture (called Continuum), a design that realises the architecture, and a proof-of-concept implementation that brings ubiquitous computing to chaotic environments. Essentially, Continuum enables an ecology at the edge of the network, between users, competing service providers from overlapping administrative domains, competing internet service providers, content providers, and software developers that want to add value to the user experience. Continuum makes the ubiquitous computing functionality orthogonal to other application logic. Existing web applications are augmented for ubiquitous computing with functionality that is dynamically compiled and injected by a middleware proxy into the web pages requested by a web browser at the user?s mobile device. This enables adaptability to environment variability, manageability without user involvement, and expansibility without changes to the mobile. The middleware manipulates self-contained software units with precise functionality (called <i>frames</i>), which help the user interact with contextual services in conjunction with the data to which they are attached. The middleware and frame design explicitly incorporates the possibility of discrepancies between the assumptions of ubiquitous-computing software developers and field realities: multiple administrative domains, unavailable service, unavailable software, and missing contextual information. A framework for discovery and authorisation addresses the chaos inherent to the paradigm through the notion of <i>role assertions</i> acquired dynamically by the user. Each assertion represents service access credentials and contains bootstrapping points for service discovery on behalf of the holding user. A proof-of-concept prototype validates the design, and implements several frames that demonstrate general functionality, including driving discovery queries over multiple service discovery protocols and making equivalences between service types, across discovery protocols.

This dissertation identifies the diluting effects that network society has had on the avant-garde subcultures, by first building a framework through which to understand the social structure and spatial production of the historical avant-garde, and then comparing this with contemporary avant-garde movements. The avant-garde is a cultural tradition that originated in modern 18th century Europe and North America, that critically responds to hegemonic power structures and mainstream cultural assumptions. I use the term “avant-garde subcultures” because my research focuses on the entire social group of the avant-garde. Most scholarship on the avant-garde has overlooked the importance that social relations, in particular supportive actors, and collaborative spaces have served in the creativity of the avant-garde. During the past twenty years, as society has shifted into a dependence on networked interactive technologies, the boundaries which protect these avant-garde spaces and social relations were diluted. As a result, avant-garde subcultures have entered a phase of recursively repeating themselves and culturally stagnating. I begin by reviewing the historical avant-garde and subcultures, building an overarching theory that explains that avant-garde is a type of subculture. Using past scholarship that maps the conceptual lineage from early bohemians to 1970s punk rock, I synthesize a set of traits which all avant-garde subcultures exhibit, and which can be used to build their genealogy. I then extend this genealogy to contemporary art practitioners, to prove that the avant-garde tradition continues to this day. Next, I develop a philosophical understanding of the importance of space for hegemonic power structures, based largely on the work of Henri Lefebvre. I explain how avant-garde subcultures produce spaces of representation in the cafes, bars and night clubs they inhabit, which challenge hegemony by being different from normal values and aesthetics. I reference first-hand accounts of these spaces of representation, to show how they enable the collaboration and creative thinking that is most often associated with the avant-garde. The avant-garde protect these spaces through a set of cultural boundaries: fashion, slang, esoteric knowledge, accumulation, and physical space. Manuel Castell's concept of network society depicts how hegemonic power structures have become pervasive, and thus can overcome the boundaries of avant-garde subcultures. As a result, avant-garde subcultures have increasingly become retrogressive and fluid. Some avant-garde practitioners, such as tactical media, have evolved methods for addressing these problems. While these are effective in continuing the avant-garde tradition of introducing difference, there are no adequate methods for producing new spaces of representation. I examine Eyebeam, an arts and technology center, which has since 1997 provided a space for many contemporary practitioners. While unique in its circumstances, Eyebeam has adopted several processes which have enabled it to overcome the diluting effects of network society, thereby providing a potential model for building future spaces of representation.

Many pervasive computing applications demand expressive situational awareness, which entails an entity in the pervasive computing environment learning detailed information about its immediate and surrounding context. Much work over the past decade focused on how to acquire and represent context information. However, this work is largely egocentric, focusing on individual entities in the pervasive computing environment sensing their own context. Distributed acquisition of surrounding context information is much more challenging, largely because of the expense of communication among these resource-constrained devices. This thesis presents Grapevine, a framework for efficiently sharing context information in a localized region of a pervasive computing network, using that information to dynamically form groups defined by their shared situations, and assessing the aggregate context of that group. Grapevine’s implementation details are presented and its performance benchmarked in both simulation and live pervasive computing network deployments. / text

The vision of pervasive computing is one of a personalized space populated with vast amounts of data that can be exploited by humans. Such Personalized Networked Spaces (PNetS) and the requisite support for general-purpose expressive spatiotemporal search of the “here” and “now” have eluded realization, due primarily to the complexities of indexing, storing, and retrieving relevant information within a vast collection of highly ephemeral data. This thesis presents the Gander search engine, founded on a novel conceptual model of search in PNetS and targeted for environments characterized by large volumes of highly transient data. We overview this model and provide a realization of it via the architecture and implementation of the Gander search engine. Gander connects formal notions of sampling a search space to expressive, spatiotemporal-aware protocols that perform distributed query processing in situ. This thesis evaluates Gander through a user study that examines the perceived usability and utility of our mobile application, and benchmarks the performance of Gander in large PNetS through network simulation. / text

This dissertation is in the area of pervasive computing. It focuses on designing platforms for storing, querying, and computing contextual information. More specifically, we are interested in platforms for storing and querying spatio-temporal events where queries exhibit locality. Recent advances in sensor technologies have made possible gathering a variety of information on the status of users, the environment machines, etc. Combining this information with computation we are able to extract context, i.e., a filtered high-level description of the situation. In many cases, the information gathered exhibits locality both in space and time, i.e., an event is likely to be consumed in a location close to the location where the event was produced, at a time whic h is close to the time the event was produced. This dissertation builds on this observation to create better platforms for computing context. We claim three key contributions. We have studied the problem of designing and optimizing spatial organizations for exchanging context. Our thesis has original theoretical work on how to create a platform based on cells of a Voronoi diagram for optimizing the energy and bandwidth required for mobiles to exchange contextual information t hat is tied to specific locations in the platform. Additionally, we applied our results to the problem of optimizing a system for surveilling the locations of entities within a given region. We have designed a platform for storing and querying spatio-temporal events exhibiting locality. Our platform is based on a P2P infrastructure of peers organized based on the Voronoi diagram associated with their locations to store events based on their own associated locations. We have developed theoretical results based on spatial point processes for the delay experienced by a typical query in this system. Additionally, we used simulations to study heuristics to improve the performance of our platform. Finally, we came up with protocols for the replicated storage of events in order to increase the fault-tolerance of our platform. Finally, in this thesis we propose a design for a platform, based on RFID tags, to support context-aware computing for indoor spaces. Our platform exploits the structure found in most indoor spaces to encode contextual information in suitably designed RFID tags. The elements of our platform collaborate based on a set of messages we developed to offer context-aware services to the users of the platform. We validated our research with an example hardware design of the RFID tag and a software emulation of the tag's functionality. / text

Service composition is a process by which the services offered by devices may be combined to produce new, more complex services. In a pervasive computing environment where many devices exist and offer services, it is particularly desirable to fully automate this composition so end users do not need to be technically sophisticated. Earlier work done by Pourreza introduced a system to do fully automated service composition and to rank the services so produced by order of expected usefulness to the end user(s). My thesis research extends the work done by Pourreza in two ways. First, and most importantly, it adds support for services that have associated Quality of Service (QoS) characteristics. This allows me to ensure that I only generate composite services that are compatible in terms of the provided and required QoS characteristics of their component services. Further, it allows me to rank the generated composite services based on how well they meet the desired QoS preferences of users. Second, I extend Pourreza’s work by adding support for compositions involving services from outside a persistent computing environment (e.g. those provided via available Internet or 3G network access). I have built a prototype for the system to illustrate feasibility and to assess the overhead of supporting QoS in composition. I have also developed a regression model (based on collected user input regarding QoS preferences for services) that can be used to effectively rank compositions based on QoS for a variety of persistent environments. My results show that my approach is both feasible and effective.

Pervasive computing implies the invisibility of the technology involved in providing ubiquity, such that technology is integrated into the environment and non-intrusive. In such a manner, computing and networking resources become diffused into physical environments, enabling users to exploit their provided functionalities such that functionality is distributed, enabling it to be controlled, monitored, managed, and extended beyond what it was initially designed to do. Moreover, computer awareness moves towards user-centricity, whereby systems seamlessly adapt to the characteristics, preferences, and current situations of users and their respective surrounding environments. Users exploit such functionalities in the form of a virtual device, whereby a collection of heterogeneous devices in the vicinity of the user are behaving as one single homogeneous device for the benefit of the user in solving some given task. This dissertation investigates the problem of dynamic composition and management of virtual devices for ad hoc multimedia service delivery and proposes an autonomous policy driven framework for virtual device management. The framework consists of a hierarchical structure of distributed elements, including autonomic elements, all working towards the self-management of virtual devices. The research presented in this dissertation addresses the functionalities of these components. More specifically, contributions are made towards the autonomous management of virtual devices, moving away from infrastructure based schemes with heavy user involvement to decentralized and zero touch (i.e., no user involvement) solutions. In doing so, the components and methodology behind a policy-driven autonomous framework for the dynamic discovery, selection, and composition of multimodal multi-device services are presented. The framework operates in an ad hoc network setting and introduces a Service Overlay Network (SON) based definition of a virtual device. Furthermore, device and service discovery, composition, integration, and adaptation schemes are designed for Mobile Ad hoc Network Environments (MANETs) enabling users to generate, on-the-fly, complex strong specific systems, embedding in a distributed manner, QoS models providing compositions that form the best possible virtual device at the time of need. Experimental studies are presented to demonstrate the performance of the proposed schemes.

Service composition is a process by which the services offered by devices may be combined to produce new, more complex services. In a pervasive computing environment where many devices exist and offer services, it is particularly desirable to fully automate this composition so end users do not need to be technically sophisticated. Earlier work done by Pourreza introduced a system to do fully automated service composition and to rank the services so produced by order of expected usefulness to the end user(s). My thesis research extends the work done by Pourreza in two ways. First, and most importantly, it adds support for services that have associated Quality of Service (QoS) characteristics. This allows me to ensure that I only generate composite services that are compatible in terms of the provided and required QoS characteristics of their component services. Further, it allows me to rank the generated composite services based on how well they meet the desired QoS preferences of users. Second, I extend Pourreza’s work by adding support for compositions involving services from outside a persistent computing environment (e.g. those provided via available Internet or 3G network access). I have built a prototype for the system to illustrate feasibility and to assess the overhead of supporting QoS in composition. I have also developed a regression model (based on collected user input regarding QoS preferences for services) that can be used to effectively rank compositions based on QoS for a variety of persistent environments. My results show that my approach is both feasible and effective.

Location information is used to provide a diverse range of services to users such as emergency, navigation, billing, security, information and advertising services. This information is derived from a broad range of indoor and outdoor technologies. The location information thus derived is of different granularity, different co-ordination system and is controlled by numerous service providers. In addition to this, broad selections of devices are used for providing these services. Having a diverse range of applications requiring location information at different levels of granularity, the need to export location information across multiple devices and the existence of different location determination technologies necessitates the need for heterogeneous location network. These networks derive location information from multiple sources and provides various location-based services to users irrespective of the medium, device or technology used. Security, user privacy and management of location information are some of the important issues that need to be addressed. The main contribution of this thesis is the design of a secure and privacy assured heterogeneous location architecture. A formal methodology was chosen to design the heterogeneous location architecture. The design of the architecture resulted in a novel key distribution protocol and a model for information flow that can be easily encapsulated into applications or architectures having similar requirements. The research also resulted in the enhancement of a proposed location framework for securing critical infrastructures using context-aware self-defending objects. The proposed enhanced framework helps to negate the security vulnerabilities introduced through the use of general-purpose computer systems in critical infrastructures.

Computing is increasingly pervading the activities of our everyday lives: at work, at home, and out on the town. When designing these pervasive systems there is a need to better understand and incorporate the context of use and yet there are limited empirical investigations into what constitutes this context. The user’s physical and social situation is an important part of their context when operating in an urban environment and thus needs to be understood and included in the interaction design of context-aware pervasive computing. This thesis has combined ideas from human computer interaction (HCI) and architecture to investigate indexicality in interface design as an instrument for incorporating physical and social context of the built environment into context-aware pervasive computing. Indexicality in interface design is a new approach to designing HCI for pervasive computing that relies on knowledge of current context to implicitly communicate between system and user. It reduces the amount of information that needs to be explicitly displayed in the interface while maintaining the usefulness and understandability of the communication.