Este trabalho apresenta uma proposta de infra-estrutura de software sensível ao contexto para a computação ubíqua (ubicomp) denominada Continuum. A área de ubicomp, também chamada de computação pervasiva, pressupõe uma forte integração com o mundo real, com foco no usuário e na manutenção de alta transparência. Para o desenvolvimento de aplicativos nesse cenário, é necessária uma infra-estrutura de software adequada. A infra-estrutura projetada é baseada no padrão da arquitetura orientada a serviços (service-oriented architecture ou SOA), fazendo uso de framework e middleware, e empregando uma redefinição da semântica siga-me. Nessa visão redefinida, os usuários podem ir para qualquer lugar carregando os dados e os aplicativos que desejam, os quais podem ser usados de forma imperceptível e integrada com o mundo real (seamless integration). O foco particular desse trabalho é sensibilidade ao contexto: a percepção de características relacionadas aos usuários e ao entorno. No trabalho são considerados os recursos disponíveis no ambiente e é mantida a história dos dados de contexto. Além disso, é proposta a representação do contexto para promover raciocínio e compartilhamento de conhecimento, empregando uma ontologia. Dessa forma, contexto é representado de uma maneira formal e bastante expressiva, diferente de muitas soluções existentes hoje em dia que ainda usam modelos de representação ad hoc. Esta tese está então na interseção destas três áreas principais: infra-estrutura de software para ubicomp, sensibilidade ao contexto e ontologias. No desenvolvimento desta tese, também examina-se o campo da computação ubíqua, e sugere-se um modelo de arquitetura geral que enfrente esses desafios fundamentais. Baseado nos requisitos estabelecidos para esse modelo, propõe-se um conjunto de serviços para o Continuum. Os serviços são projetados considerando o trabalho previamente desenvolvido pelo nosso grupo de pesquisa, mais especificamente o projeto ISAM, e particularmente o middleware EXEHDA. A proposta estende esses projetos, adicionando aspectos que não haviam sido considerados no momento do seu desenvolvimento. Particularmente, o suporte a sensibilidade de contexto é melhorado com a proposta de uma ontologia para a formalização da informação de contexto. Algumas análises, usando a metodologia de estudo de caso, foram conduzidas para apreciar as principais proposições da tese. Baseado nessas avaliações, foram apresentadas algumas lições aprendidas e traçada a conclusão do trabalho. Como resultado, Continuum é uma infra-estrutura de software que endereça muitos aspectos da computação ubíqua, integrando imperceptivelmente diferentes desafios. / The present work is a proposal of a context-aware software infrastructure for ubiquitous computing (ubicomp) named Continuum. The ubicomp area, also called pervasive computing, presupposes a strong integration with the real world, with focus on the user and on keeping high transparency. For the development of applications in this scenario, we need an adequate software infrastructure. The infrastructure designed in this work is based on service-oriented architecture (SOA), making use of framework and middleware, and employing a redefinition of follow-me semantics. In this redefined vision, users can go anywhere carrying the data and application they want, which they can use in a seamlessly integrated fashion with the real world. The specific focus of our work is context awareness: the perception of characteristics related to users and surroundings. We consider the resources available in the environment and keep a history of context data. Furthermore, we propose the representation of context to promote reasoning and knowledge sharing, using ontology. In this way, context is represented in a considerably expressive, formal approach, different from many solutions that exist today, which still use ad hoc representations models. Our work is then at the intersection of these three main areas: software infrastructures for ubicomp, context awareness, and ontologies. In the development of this thesis, we also survey the field of ubiquitous computing, suggesting a general architectural model to deal with its fundamental challenges. Based on the established requirements for this model, we propose a set of services for Continuum. The services are designed considering the previous works developed by our research group, namely ISAM (Infra-estrutura de Suporte às Aplicações Móveis – Mobile Applications Support Infrastructure), and particularly the middleware EXEHDA (Execution Environment for Highly Distributed Applications). We further extend these projects, by adding aspects to them that had not been considered at the time of their development. Particularly, we improve context awareness support, proposing an ontology for the formalization of context information. We have conducted some analysis, using case study methodology, to evaluate the main propositions of our work. Based on these assessments, we present lessons learned and draw the conclusion of our work. As a result, Continuum is a software infrastructure that addresses many aspects of ubiquitous computing, seamlessly integrating many different challenges.

The widespread use of mobile devices and the rise of Global Navigation Satellite Systems (GNSS) have allowed mobile tracking applications to become very popular and valuable in outdoor environments. However, tracking pedestrians in indoor environments with Global Positioning System (GPS)-based schemes is still very challenging given the lack of enough signals to locate the user. Along with indoor tracking, the ability to recognize pedestrian behavior and activities can lead to considerable growth in location-based applications including pervasive healthcare, leisure and guide services (such as, museum, airports, stores, etc.), and emergency services, among the most important ones. This thesis presents a system for pedestrian tracking and activity recognition in indoor environments using exclusively common off-the-shelf sensors embedded in smartphones (accelerometer, gyroscope, magnetometer and barometer). The proposed system combines the knowledge found in biomechanical patterns of the human body while accomplishing basic activities, such as walking or climbing stairs up and down, along with identifiable signatures that certain indoor locations (such as turns or elevators) introduce on sensing data. The system was implemented and tested on Android-based mobile phones with a fixed phone position. The system provides accurate step detection and count with an error of 3% in flat floor motion traces and 3.33% in stairs. The detection of user changes of direction and altitude are performed with 98.88% and 96.66% accuracy, respectively. In addition, the activity recognition module has an accuracy of 95%. The combination of modules leads to a total tracking error of 90.81% in common human motion indoor displacements.

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.

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

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.

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.