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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Personalised assistance for fuel-efficient driving

Gilman, Ekaterina, Keskinarkaus, Anja, Tamminen, Satu, Pirttikangas, Susanna, Röning, Juha, Riekki, Jukka 18 November 2020 (has links)
Recent advances in technology are changing the way how everyday activities are performed. Technologies in the traffic domain provide diverse instruments of gathering and analysing data for more fuel-efficient, safe, and convenient travelling for both drivers and passengers. In this article, we propose a reference architecture for a context-aware driving assistant system. Moreover, we exemplify this architecture with a real prototype of a driving assistance system called Driving coach. This prototype collects, fuses and analyses diverse information, like digital map, weather, traffic situation, as well as vehicle information to provide drivers in-depth information regarding their previous trip along with personalised hints to improve their fuel-efficient driving in the future. The Driving coach system monitors its own performance, as well as driver feedback to correct itself to serve the driver more appropriately.
112

Context aware voice user interface

Demeter, Nora January 2014 (has links)
In this thesis I address the topic of a non-visual approach for interaction on mobile,as an alternative to their existing visual displays in situations where hands free usageof the device is preferred. The current technology will be examined through existingwork with special attention to its limitations, which user groups are currently using anysort of speech recognition or voice command functions and look at in which scenariosare these the most used and most desired. Then I will examine through interviews whypeople trust or distrust voice interactions and how they feel about the possibilities andlimitations of the technology at hand, how individual users use this currently and wheredo they see the technology in the future. After this I will develop an alternative voiceinteraction concept, and validate it through a set of workshops.
113

Adaptiv bildladdning i en kontextmedveten webbtjänst

Halldén, Albin, Schönemann, Madeleine January 2014 (has links)
Information på webben konsumeras idag via en mängd heterogena enheter. Faktorer som nätverksunderlag och skärmupplösning påverkar vilken bild som är lämplig att leverera till klienten, då en bild i sitt originaltillstånd på en tekniskt begränsad enhet tar lång tid att hämta samt kräver en stor datamängd. Eftersom surfandet på mobila enheter via mobila nätverk förväntas att öka är en lösning för adaptiv bildladdning relevant. Syftet är att undersöka huruvida en webbtjänst, bestående av en klient och en server, kan avgöra bäst lämpad bildkvalitet att leverera till klienten, baserat på dennes aktuella nätverksprestanda och skärmupplösning. En enhet med lägre skärmupplösning och ett långsammare nätverk berättigar en bild i sämre kvalitet och lägre bildupplösning. Därmed förkortas hämtnings- tiden och datamängden reduceras, vilket bidrar till en förbättrad användarupplevelse.Uppsatsen presenterar och utvärderar flera lösningar för adaptiv bildladdning. Lös- ningarna baseras på två parametrar: bredden på klientens webbläsarfönster samt svarstid mellan klient och server, med hjälp av javascript. Dessa parametrar står till grund för den skalning av storlek och kvalitet som sedan appliceras på bilden. Bilden tillhandahålls klien- ten genom någon av de två leveransmetoderna fördefinierade bilder, där flera olika versioner av bilden lagras på servern, och dynamiska bilder, där bilderna i realtid renderas på servern genom gd-biblioteket i php utifrån på originalbilden. Tre typer av adaptiv bildladdning – kvalitetsadaption, storleksadaption och en kombination av de båda, undersöks med av- seende på tidsåtgång och levererad datamängd. Dessa utvärderas sedan i förhållande till basfallet bestående av originalbilderna.Att använda någon typ av adaptionsmetod är i 14 av 15 fall bättre än att enbart leverera originalbilder. Bäst resultat ger kombinerad adaption på enheter med mindre skärmupp- lösning och långsammare nätverk men är även gynnsamt för enheter med medelsnabba nätverk och enheter med stöd för högre skärmupplösning. Både fördefinierad och dyna- misk leveransmetod ger bra resultat men då den dynamiska leveransmetodens skalbarhet med flera parallella anslutningar inte är känd rekommenderas fördefinierade bilder. / Today, information on the web is consumed via a variety of heterogeneous devices. Factors, such as network connection and screen resolution, affects which image that is the most suitable to deliver to the client. An image in its original condition, in a technically limited device, takes a long time to download and requires a large amount of data. Since the number of devices browsing the internet via mobile networks are expected to increase, a solution for adaptive image loading is needed. The aim of this thesis is to explore whether a web service, consisting of a client and a server, can determine the best suited image that should be delivered to the client. This is based on the client’s current network connection and screen resolution. A device with a lower screen resolution and a slower network connection requires an image of lower quality and lower resolution. Thus, the download time can be shortened and the data volume reduced, contributing to improved user experience.Our adaptive solution is based on two measurements – the width of the client’s browser window and the latency between the client and the server – using javascript. These para- meters are the basis for the scaling of the size and quality which applies to the image. The image is provided to the client by one of the two delivery methods: “predefined images”, where several different versions of the image are stored on the server, and “dynamic images”, where the images are rendered on the server by the gd library in php, based on the original image. Three types of adaptive image loading – quality adaptation, size adaptation and a combination of both, are investigated considering delivery time and the amount of data delivered. These are then evaluated in relation to the base case consisting of the original images.Using some type of adaptation method is in 14 out of 15 cases better than simply delivering the original images. The best results are given by the combined adaption method on devices with smaller screen resolutions and slower network connections, but is also beneficial for devices with medium speed connections and devices that support higher screen resolutions. Both predefined and dynamic delivery methods shows good results, but since the dynamic delivery method’s scalability with multiple concurrent clients is not known, it is recommended to use predefined images.
114

Forming Emergent Configurations in Smart Office IoT Systems

Gullstrand, Simon, Wahlfrid, Jonas January 2017 (has links)
In this thesis, we examine how Emergent Configurations are formed to manageThings and People for the purpose of achieving the user’s goal of repairing a coffeemachine in the dynamic environment of a smart office. We develop an architecturein the form of requirement and design artifacts as well as a realization of the GoalManager component in the Emergent Configuration Manager which is responsiblefor the forming of Emergent Configurations, using the novel Emergent ConfigurationIoT system engineering approach. To demonstrate the capability of the realizationwe developed multiple case scenarios which correspond to the context dynamicity ofa smart office environment. The results of this study introduce an architecture forthe Goal Manager component and demonstrate that the novel engineering approach,Emergent Configuration, is a feasible way of managing IoT systems in the smart officecategory.
115

Metode realizacije kontekstualnih platformi i kontekstualnih korisničkih sprega za primene u uređajima potrošačke elektonike / Methods of implementation of context-aware platforms and context-aware user interfaces for applications in consumer electronics

Bjelica Milan 11 February 2013 (has links)
<p>U okviru disertacije predstavljene su metode realizacije kontekstualnih platformi i kontekstualnih korisničkih sprega za uređaje potrošačke elektronike. Predloženi su algoritmi semantizacije konteksta i procene zauzetosti korisnika, arhitektura rešenja i rezultati evaluacije.</p><p>&nbsp;</p> / <p>In this dissertation methods of implementation of context-aware platforms and context-aware user interfaces for applications in consumer electronics are presented. The work includes the proposition of algorithms for context semantization and user availability estimation, architecture of the solution as well as the results of evaluation experiments.</p>
116

Délivrance de servcies médias ubiquitaires adaptés selon le contexte au sein de réseaux de nouvelles générations / Context-awareness for ubiquitous media service delivery in next generation networks

Arnaud, Julien 17 December 2012 (has links)
Les récentes avancées technologiques permettent désormais la fabrication de terminaux mobiles de plus en plus compacts et dotés de plusieurs interfaces réseaux. Le nouveau modèle de consommation de médias se résume par le concept "Anytime, Anywhere, Any Device" et impose donc de nouvelles exigences en termes de déploiement de services ubiquitaires. Cependant la conception et le developpement de réseaux ubiquitaires et convergents de nouvelles générations soulèvent un certain nombre de défis techniques. Les standards actuels ainsi que les solutions commerciales pourraient être affectés par le manque de considération du contexte utilisateur. Le ressenti de l'utilisateur concernant certains services multimédia tels que la VoIP et l'IPTV dépend fortement des capacités du terminal et des conditions du réseau d'accès. Cela incite les réseaux de nouvelles générations à fournir des services ubiquitaires adaptés à l'environnement de l'utilisateur optimisant par la même occasion ses resources. L'IP Multimedia Subsystem (IMS) est une architecture de nouvelle génération qui centralise l'accès aux services et permet la convergence des réseaux fixe/mobile. Néanmoins, l'évolution de l'IMS est nécessaire sur les points suivants :- l'introduction de la sensibilité au contexte utilisateur et de la PQoS (Perceived QoS) : L'architecture IMS ne prend pas en compte l'environnement de l'utilisateur, ses préférences et ne dispose pas d'un méchanisme de gestion de PQOS. Pour s'assurer de la qualité fournit à l'utilisateur final, des informations sur l'environnement de l'utilisateur ainsi que ses préférences doivent transiter en cœur de réseau afin d'y être analysés. Ce traitement aboutit au lancement du service qui sera adapté et optimisé aux conditions observées. De plus pour le service d'IPTV, les caractéristiques spatio-temporelles de la vidéo influent de manière importante sur la PQoS observée côté utilisateur. L'adaptation des services multimédias en fonction de l'évolution du contexte utilisateur et de la nature de la vidéo diffusée assure une qualité d'expérience à l'utilisateur et optimise par la même occasion l'utilisation des ressources en cœur de réseau.- une solution de mobilité efficace pour les services conversationnels tels que la VoIP : Les dernières publications 3GPP fournissent deux solutions de mobilité: le LTE propose MIP comme solution de mobilité alors que l'IMS définit une mobilité basée sur le protocole applicatif SIP. Ces standards définissent le système de signalisation mais ne s'avancent pas sur la gestion du flux média lors du changement d'interface réseau. La deuxième section introduit une étude comparative détaillée des solutions de mobilité dans les NGNs.Notre première contribution est la spécification de l'architecture globale de notre plateforme IMS sensible au contexte utilisateur réalisée au sein du projet Européen ADAMANTIUM. Nous détaillons tout d'abord le serveur MCMS intelligent placé dans la couche application de l'IMS. Cet élément récolte les informations de qualité de services à différents équipements réseaux et prend la décision d'une action sur l'un de ces équipements. Ensuite nous définissons un profil utilisateur permettant de décrire son environnement et de le diffuser en coeur de réseau. Une étude sur la prédiction de satisfaction utilisateur en fonction des paramètres spatio-temporels de la vidéo a été réalisée afin de connaître le débit idéal pour une PQoS désirée.Notre deuxième contribution est l'introduction d'une solution de mobilité adaptée aux services conversationnels (VoIP) tenant compte du contexte utilisateur. Notre solution s'intègre à l'architecture IMS existante de façon transparente et permet de réduire le temps de latence du handover. Notre solution duplique les paquets de VoIP sur les deux interfaces actives pendant le temps de la transition. Parallèlement, un nouvel algorithme de gestion de mémoire tampon améliore la qualité d'expérience pour le service de VoIP. / The latest advances in technology have already defied Moore’s law. Thanks to research and industry, hand-held devices are composed of high processing embedded systems enabling the consumption of high quality services. Furthermore, recent trends in communication drive users to consume media Anytime, Anywhere on Any Device via multiple wired and wireless network interfaces. This creates new demands for ubiquitous and high quality service provision management. However, defining and developing the next generation of ubiquitous and converged networks raise a number of challenges. Currently, telecommunication standards do not consider context-awareness aspects for network management and service provisioning. The experience felt by the end-user consuming for instance Voice over IP (VoIP) or Internet Protocol TeleVision (IPTV) services varies depending mainly on user preferences, device context and network resources. It is commonly held that Next Generation Network (NGN) should deliver personalized and effective ubiquitous services to the end user’s Mobile Node (MN) while optimizing the network resources at the network operator side. IP Multimedia Subsystem (IMS) is a standardized NGN framework that unifies service access and allows fixed/mobile network convergence. Nevertheless IMS technology still suffers from a number of confining factors that are addressed in this thesis; amongst them are two main issues :The lack of context-awareness and Perceived-QoS (PQoS):-The existing IMS infrastructure does not take into account the environment of the user ,his preferences , and does not provide any PQoS aware management mechanism within its service provisioning control system. In order to ensure that the service satisfies the consumer, this information need to be sent to the core network for analysis. In order to maximize the end-user satisfaction while optimizing network resources, the combination of a user-centric network management and adaptive services according to the user’s environment and network conditions are considered. Moreover, video content dynamics are also considered as they significantly impact on the deduced perceptual quality of IPTV services. -The lack of efficient mobility mechanism for conversational services like VoIP :The latest releases of Third Generation Partnership Project (3GPP) provide two types of mobility solutions. Long-Term Evolution (LTE) uses Mobile IP (MIP) and IMS uses Session Initiation Protocol (SIP) mobility. These standards are focusing on signaling but none of them define how the media should be scheduled in multi-homed devices. The second section introduces a detailed study of existing mobility solutions in NGNs. Our first contribution is the specification of the global context-aware IMS architecture proposed within the European project ADAptative Management of mediA distributioN based on saTisfaction orIented User Modeling (ADAMANTIUM). We introduce the innovative Multimedia Content Management System (MCMS) located in the application layer of IMS. This server combines the collected monitoring information from different network equipments with the data of the user profile and takes adaptation actions if necessary. Then, we introduce the User Profile (UP) management within the User Equipment (UE) describing the end-user’s context and facilitating the diffusion of the end-user environment towards the IMS core network. In order to optimize the network usage, a PQoS prediction mechanism gives the optimal video bit-rate according to the video content dynamics. Our second contribution in this thesis is an efficient mobility solution for VoIP service within IMS using and taking advantage of user context. Our solution uses packet duplication on both active interfaces during handover process. In order to leverage this mechanism, a new jitter buffer algorithm is proposed at MN side to improve the user’s quality of experience. Furthermore, our mobility solution integrates easily to the existing IMS platform.
117

Modèles sémantiques et raisonnements réactif et narratif, pour la gestion du contexte en intelligence ambiante et en robotique ubiquitaire / Semantic models, reactive and narrative reasoning for context management in ambient intelligence and ubiquitous robotics

Sabri, Lyazid 01 July 2013 (has links)
Avec l'apparition des paradigmes des systèmes ubiquitaires ou omniprésents et de l'intelligence ambiante, on assiste à l'émergence d'un nouveau domaine de recherche visant à créer des environnements ou écosystèmes intelligents pouvant offrir une multitude de services permettant d'améliorer la qualité de vie, l'état physique et mental, et le bien-être social des usagers. Dans cette thèse, nous nous focalisons sur la problématique de la représentation sémantique des connaissances et du raisonnement dans le cadre des systèmes à intelligence ambiante et des robots ubiquitaires. Nous proposons deux modèles sémantiques permettant d'améliorer les fonctions cognitives de ces systèmes en termes de gestion du contexte. Au premier modèle, de type ontologique, sont associés un langage de règles et un raisonnement réactif pour la sensibilité au contexte. Pour prendre en compte le caractère dynamique du contexte et assurer une prise de décision cohérente, le mode de raisonnement retenu garantit deux propriétés essentielles : la décidabilité et la non-monotonie. Le deuxième modèle, également de type ontologique, complète le modèle précédent en termes d'expressivité pour la représentation de contextes non-triviaux et/ou liés au temps. Il s'appuie sur des relations n-aires et une représentation narrative des événements pour inférer des causalités entre événements et reconnaitre des contextes complexes non-observables à partir d'événements passés et courants. Les modèles proposés ont été mis en oeuvre et validés sur la plateforme ubiquitaire d'expérimentation du LISSI à partir de trois scenarii d'assistance cognitive et de reconnaissance de contexte / With the appearance of the paradigms of ubiquitous systems and ambient intelligence, a new domain of research is emerging with the aim of creating intelligent environments and ecosystems, that can provide multiple services that can improve quality of life, the physical and mental status and the social wellness of the users. In this thesis, we address the problem of semantic knowledge representation and reasoning, in the context of ambient intelligent systems and ubiquitous robots. We propose two semantic models that improve the cognitive functions of these systems, in terms of context recognition, and context adaptation. The first one is an ontology-based model, which is associated with a rule language to model reactive reasoning process on contextual knowledge. To take into account the dynamicity of context and insure coherent decision-making, this process guarantees two essential properties: decidability and non-monotonic reasoning. The second model is also an ontology-based model that completes the previous model in terms of expressiveness for semantic representation of non-trivial contexts with temporal dimension It is based on n-ary relations and a narrative representation of events for inferring causalities between events, and therefore to build the chronological context of a situation as from past and current events. The proposed models have been implemented on the ubiquitous experimental platform of LISSI, and validated through three scenarios for cognitive assistance and context recognition
118

Sélection contextuelle de services continus pour la robotique ambiante / Contextual selection of continuous services applied to ambient robotics

Cogrel, Benjamin 18 November 2013 (has links)
La robotique ambiante s'intéresse à l'introduction de robots mobiles au sein d'environnements actifs où ces derniers fournissent des fonctionnalités alternatives ou complémentaires à celles embarquées par les robots mobiles. Cette thèse étudie la mise en concurrence des fonctionnalités internes et externes aux robots, qu'elle pose comme un problème de sélection de services logiciels. La sélection de services consiste à choisir un service ou une combinaison de services parmi un ensemble de candidats capables de réaliser une tâche requise. Pour cela, elle doit prédire et évaluer la performance des candidats. Ces performances reposent sur des critères non-fonctionnels comme la durée d'exécution, le coût ou le bruit. Ce domaine applicatif a pour particularité de nécessiter une coordination étroite entre certaines de ses fonctionnalités. Cette coordination se traduit par l'échange de flots de données entre les fonctionnalités durant leurs exécutions. Les fonctionnalités productrices de ces flots sont modélisées comme des services continus. Cette nouvelle catégorie de services logiciels impose que les compositions de services soient hiérarchiques et introduit des contraintes supplémentaires pour la sélection de services. Cette thèse met en évidence la présence d'un important couplage non-fonctionnel entre les performances des instances de services de différents niveaux, même lorsque les flots de données sont unidirectionnels. L'approche proposée se concentre sur la prédiction de la performance d'une instance de haut-niveau sachant son organigramme à l'issue de la sélection. Un organigramme regroupe l'ensemble des instances de services sollicitées pour réaliser une tâche de haut-niveau. L'étude s'appuie sur un scénario impliquant la sélection d'un service de positionnement en vue de permettre le déplacement d'un robot vers une destination requise. Pour un organigramme considéré, la prédiction de performance d'une instance de haut-niveau de ce scénario introduit les exigences suivantes : elle doit (i)être contextuelle en tenant compte, par exemple, du chemin suivi pour atteindre la destination requise, (ii) prendre en charge le remplacement d'une instance de sous-service suite à un échec ou, par extension, de façon opportuniste. En conséquence, cette sélection de services est posée comme un problème de prise de décision séquentielle formalisé à l'aide de processus de décision markoviens à horizon fini. La dimensionnalité importante du contexte en comparaison à la fréquence des déplacements du robot rend inadaptées les méthodes consistant à apprendre directement une fonction de valeur ou une fonction de transition. L'approche proposée repose sur des modèles de dynamique locaux et exploite le chemin de déplacement calculé par un sous-service pour estimer en ligne les valeurs des organigrammes disponibles dans l'état courant. Cette estimation est effectuée par l'intermédiaire d'une méthode de fouille stochastique d'arbre, Upper Confidence bounds applied to Trees / Ambient robotics aims at introducing mobile robots in active environments where the latter provide new or alternative functionalities to those shipped by mobile robots. This thesis studies the competition between robot and external functionalities, which is set as a service selection problem. Service selection consists in choosing a service or a combination of services among a set of candidates able to fulfil a given request. To do this, it has to predict and evaluate candidate performances. These performances are based on non-functional requirements such as execution time, cost or noise. This application domain requires tight coordination between some of its functionalities. Tight coordination involves setting data streams between functionalities during their execution. In this proposal, functionalities producing data streams are modelled as continuous services. This new service category requires hierarchical service composition and adds some constraints to the service selection problem. This thesis shows that an important non-functional coupling appears between service instances at different levels, even when data streams are unidirectional. The proposed approach focuses on performance prediction of an high-level service instance given its organigram. This organigram gathers service instances involved in the high-level task processing. The scenario included in this study is the selection of a positioning service involved in a robot navigation high-level service. For a given organigram, performance prediction of an high-level service instance of this scenario has to: (i) be contextual by, for instance, considering moving path towards the required destination, (ii) support service instance replacement after a failure or in an opportunist manner. Consequently, this service selection is set as a sequential decision problem and is formalized as a finite-horizon Markov decision process. Its high contextual dimensionality with respect to robot moving frequency makes direct learning of Q-value functions or transition functions inadequate. The proposed approachre lies on local dynamic models and uses the planned moving path to estimate Q-values of organigrams available in the initial state. This estimation is done using a Monte-Carlo tree search method, Upper Confidence bounds applied to Trees
119

[en] A MULTIAGENT BASED CONTEXT AWARE AND SELF ADAPTIVE MODEL FOR VIRTUAL NETWORK PROVISIONING / [pt] UM SISTEMA MULTI AGENTE AUTO ADAPTATIVO BASEADO EM CONHECIMENTO DE CONTEXTO PARA GERENCIAMENTO DE REDES VIRTUAIS

CAROLINA VALADARES 06 March 2015 (has links)
[pt] Pesquisas recentes em Virtualização de Redes focaram no problema conhecido como ossificação da Internet (Anderson et al., 2005), onde múltiplas redes virtuais (Virtual Networks - VN) independentes (Anderson et al., 2005) que exibem um alto grau de autonomia compartilham recursos físicos e podem prover serviços com diferentes graus de qualidade. Nesse sentido, pesquisas na área de Redes de Computadores e Sistemas Distribuídos deram passos evolutivos em repensar o projeto e os princípios arquiteturais de uma VN (Blumenthal e Clark, 2001) (Houidi et al., 2008). Entretanto, até onde sabemos, houve pouca investigação sobre o comportamento autonômico de tais arquiteturas (Prehofer e Bettstetters, 2005) (Movahedi et al., 2012). Sendo assim, esta pesquisa descreve uma tentativa de aplicar princípios de Sistemas Multi-Agentes (Multiagent Systems - MAS) para projetar um modelo autonômico e auto-adaptativo para o gerenciamento de redes virtuais (Virtual Networking Provisioning - VNP). Modelo esse que preenche uma lacuna na atual arquitetura da Internet. Além disso, fornecemos uma análise dos requisitos de um gerenciador auto-adaptativo para projetar um modelo autonômico confiável que é capaz de auto-organizar seus próprios recursos, sem controle, externo, para lidar com mudanças no ambiente. Tal comportamento adaptativo será necessário tendo em vista que a próxima geração da Internet está em evolução. Através da nossa avaliação, demonstramos que o modelo atinge seu propósito principal de auto-organizar uma VN eficientemente, dado que ele é capaz de antecipar cenáris críticos e executar planos adaptativos correspondentes. / [en] Recent research in Network Virtualization has focused on the Internet ossification problem (Anderson et al., 2005) whereby multiple independente virtual networks (VN) (Anderson et al., 2005) that exhibit a high degree of autonomy share physical resources and can provide services with varying degrees of quality. Thus, the Network field has taken evolutionary steps on re-thinking the design and architectural principles of VN (Blumenthal e Clark, 2001) (Houidi et al., 2008). However, to the best of our knowledge, there has been little investigation into the autonomic behaviourof such architectures (Prehofer e Bettstetter, 2005) (Movahedi et all., 2012). This paper describes na attempt to use Multiagent System (MAS) principles to design na autonomic and self-adaptative model for virtual network provisioning (VPN) that fills a gap in the current Internet architecture. In addition, we provide na analysis of the requirements of self-adaptive provisioning for designing a reliable autonomic model that is able to self-organize its own resources, with no external control, in order to cope with environment changes. Such behavior will be required as the next negeneration Internet evolves. Through our evaluation, we demonstrate that the model achieves its main purpose of efficiently self-organizing the VN, since it is able to anticipate critical scenarios and trigger corresponding adaptive plans.
120

[en] CONTEXT-SENSITIVE EXCEPTION HANDLING / [pt] TRATAMENTO DE EXCEÇÕES SENSÍVEL AO CONTEXTO

KARLA NAZARE FERREIRA DAMASCENO 23 October 2006 (has links)
[pt] Tratamento de erros em aplicações móveis sensíveis ao contexto não é uma tarefa trivial devido às características peculiares destes sistemas, como mobilidade, comunicação assíncrona e aumento de imprevisibilidade. Mecanismos convencionais de tratamento de exceções não podem ser utilizados por vários motivos. Primeiro, a propagação de erros deve considerar as mudanças contextuais que ocorrem constantemente nestes sistemas. Segundo, as atividades de recuperação de erros e a estratégia de tratamento de exceções também precisam freqüentemente ser selecionadas de acordo com as informações de contexto. Terceiro, a própria caracterização de uma exceção pode depender do contexto dos dispositivos envolvidos. Embora vários middlewares orientados a contexto ofereçam suporte ao desenvolvimento de aplicações móveis, estes sistemas raramente fornecem suporte adequado ao tratamento de exceções. Este trabalho realiza uma análise das soluções existentes para tratamento de exceções, considerando os requisitos de sensibilidade ao contexto. Além disso, são propostos um modelo para tratamento de exceções sensível ao contexto e um mecanismo implementado a partir de MoCA (Mobile Collaboration Architecture). MoCA é um middleware publish-subscribe que oferece suporte ao desenvolvimento de aplicações móveis colaborativas através da incorporação de serviços de contexto. Finalmente, este trabalho avalia o mecanismo de exceções proposto através de sua utilização em alguns protótipos de aplicações colaborativas desenvolvidas a partir de MoCA. Através do mecanismo, foram implementadas diferentes estratégias de tratamento de exceções que consideram as informações de contexto das aplicações. / [en] Context-sensitive exception handling on mobile systems is not a trivial task due to their intrinsic characteristics: mobility, asynchrony and increased unpredictability. Conventional mechanisms of exception handling can not be used for many reasons. First, error propagation needs considering the contextual changes that often occur in these systems. Second, error recovery and exception handling strategies also frequently need to be selected according to contextual information. Third, the characterization of an exception may depend on the contextual situation of involved devices. Even though there are now several context-oriented middleware systems that provide support for the development of mobile applications, they rarely provide explicit and adequate features for contextsensitive exception handling. This work presents an analysis of existing exception handling mechanisms, which to some extent consider the context-awareness requirements. Besides, it proposes a general model for context-sensitive exception handling and a supporting mechanism implemented using the MoCA (Mobile Collaboration Architecture) infrastructure. MoCA is a publish-subscribe middleware supporting the development of collaborative mobile applications by incorporating explicit services to empower software agents with contextsensitiveness. Finally, this paper reports our experience in implementing contextaware exception handling strategies in some prototype collaborative applications built with the MoCA system.

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