This thesis aims to offer a comprehensive analysis of peer-to-peer-based file-sharing by focusing on the discourses about use, agency and motivation involved, and how they interrelate with the infrastructural properties of file-sharing. Peer-to-peer-based file-sharing is here defined as the unrestricted duplication of digitised media content between autonomous end-nodes on the Internet. It has become an extremely popular pastime, largely involving music, film, games and other media which is copied without the permission of the copyright holders. Due to its illegality, the popular understanding of the phenomenon tends to overstate its conflictual elements, framing it within a legalistic 'copyfight'. This is most markedly manifested in the dichotomised image of file-sharers as 'pirates' allegedly opposed to the entertainment industry. The thesis is an attempt to counter this dichotomy by using a more heterodox synthesis of perspectives, aiming to assimilate the phenomenon's complex intermingling of technological, infrastructural, economic and political factors. The geographic context of this study is Sweden, a country characterised by early broadband penetration and subsequently widespread unrestricted file-sharing, paralleled by a lively and well-informed public debate. This gives geographic specificity and further context to the file-sharers' own justificatory discourses, serving to highlight and problematise some principal assumptions about the phenomenon. The thesis thus serves as a geographically contained case study which will have analytical implications outside of its immediate local context, and as an inquiry into two aspects of file-sharer argumentation: the ontological understandings of digital technology and the notion of agency. These, in turn, relate to particular forms of sociality in late modernity. Although the agencies and normative forces involved are innumerable, controversies about agency tend to order themselves in a more comprehensive way, as they are appropriated discursively. The invocation to agency that is found in the justificatory discourses - both in the public debate and among individual respondents - thus allows for a more productive and critically attentive understanding of the phenomenon than previously

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-09-11T20:15:52Z No. of bitstreams: 1 EDUARDO DE LUCENA FALCÃO – TESE (PPGCC) 2018.pdf: 1866534 bytes, checksum: df5c1f1f8a93b43bb91c35f1cc373e17 (MD5) / Made available in DSpace on 2018-09-11T20:15:52Z (GMT). No. of bitstreams: 1 EDUARDO DE LUCENA FALCÃO – TESE (PPGCC) 2018.pdf: 1866534 bytes, checksum: df5c1f1f8a93b43bb91c35f1cc373e17 (MD5) Previous issue date: 2018-04-24 / Capes / Provedores privados de computação na nuvem poderiam obter considerável benefício mútuo ao operar suas infraestruturas de forma federada. Tal operação permite que a demanda excedente de um provedor possa ser atendida por outros provedores que estejam experimentando uma baixa demanda naquele mesmo instante. Sob uma ótica de mercado, federações com arquitetura descentralizada têm como principal desafio a promoção de cooperação entre indivíduos egoístas e racionais em um cenário que não dispõe de uma autoridade central e confiável. Este trabalho se concentra em arquiteturas de mercado descentralizado, baseadas em mecanismos de reciprocidade, para suporte a federações P2P (Peer-to-Peer) de provedores de computação na nuvem. Nos mecanismos de reciprocidade, um indivíduo utiliza o histórico de comportamentos de cooperação dos demais indivíduos para doar seus recursos aos que forem mais recíprocos. A maioria dessas estratégias se atém à priorização dos participantes (a quem devo doar?) de acordo com métricas tais como reputação ou grau de reciprocidade. Essa estratégia é suficiente para promover cooperação e assegurar aos participantes cooperativos os melhores níveis possíveis de satisfação (percentual de requisições atendidas). Porém, em cenários com baixa contenção de recursos, a priorização por si só não é suficiente para evitar o aproveitamento por parte de indivíduos não-cooperativos e garantir paridade (percentual de recursos retribuídos). Neste sentido, este trabalho propõe que mecanismos de reciprocidade, especialmente aqueles baseados em reciprocidade direta, sejam estendidos com um laço de controle retroalimentado que regula a quantidade de recursos que cada nuvem deveria ofertar à federação. Quando cada participante cooperativo controla de maneira individual a quantidade de recursos ofertada à federação, tem-se como resultado um controle indireto da contenção de recursos, que por sua vez é mantida em um patamar que assegura aos participantes cooperativos níveis adequados de satisfação e paridade. Por fim, é apresentada uma investigação acerca da utilização de uma forma mais limitada de reciprocidade indireta, a reciprocidade transitiva, que pode ser utilizada conjuntamente com mecanismos de reciprocidade direta, para evitar impasses gerados pela assimetria de tempo/interesses, aquecendo a economia da federação e consequentemente provendo maiores níveis de paridade e satisfação aos nós cooperativos. / Private cloud providers could obtain considerable benefits from operating their infrastructures within a federation. Such operation allows a provider’s exceeding demand to be met by other providers experimenting a resource underutilization on the same moment. From a market perspective, federations with decentralized architecture have as main challenge the promotion of cooperation among rational selfish individuals in a context with no central trusted authorities. This work focuses in decentralized market architectures, based on reciprocity mechanisms, to support P2P (Peer-to-Peer) federations of cloud providers. In reciprocity mechanisms, an individual uses the history of behaviors of other individuals, reflecting their cooperation levels, in order to prioritize the provision of resource to those shown to be the most reciprocative. Most of these strategies are restricted to the prioritization of participants (to whom should I donate?) according to metrics such as reputation or degree of reciprocity. This strategy is sufficient to promote cooperation and assure cooperative participants the best possible levels of satisfaction (percentage of requests met). However, in low resource contention scenarios, prioritization alone is not sufficient to avoid resource provision to non-cooperative individuals and thus to guarantee fairness (percentage of resources reciprocated). In this sense, this work proposes that mechanisms of reciprocity, especially those based on direct reciprocity, be extended with a feedback control loop that regulates the amount of resources that each cloud should offer to the federation. When each cooperative participant controls individually the amount of resources offered to the federation, there is an indirect control of resource contention, which in turn is kept at a level that ensures cooperative participants adequate levels of satisfaction and fairness. Finally, an investigation on the use of a more limited form of indirect reciprocity is presented, the transitive reciprocity, which can be used in conjunction with direct reciprocity mechanisms to avoid deadlocks generated by time/interest asymmetry, moving the federation’s economy and consequently assuring higher levels of fairness and satisfaction to cooperative nodes.

This master´s thesis is concerned in problematic of data searching on the Internet which is very actual. It focuses mainly how centralized, decentralized and hybrid searching work. This paper also compares advantages and disadvantages of these methods and describes principles and syntaxes of most-used search engines. Possibilities of use intelligent search agents are shown here as well. The practical part of this thesis is dedicated to development and testing of specialized application for searching. This program enable user to harvest contacts of companies in accordance to defined key-words and creates database file from obtained contacts.

Native Multicast plays an important role in distributing and managing delivery of some of the most popular Internet applications, such as IPTV and media delivery. However, due to patchy support and the existence of multiple approaches for Native Multicast, the support for Native Multicast is fragmented into isolated areas termed Multicast Islands. This renders Native Multicast unfit to be used as an Internet wide application. Instead, Application Layer Multicast, which does not have such network requirements but is more expensive in terms of bandwidth and overhead, can be used to connect the native multicast islands. This thesis proposes Opportunistic Native Multicast (ONM) which employs Application LayerMulticast (ALM), on top of a DHT-based P2P overlay network, and Automatic Multicast Tunnelling (AMT) to connect these islands. ALM will be used for discovery and initiating the AMT tunnels. The tunnels will encapsulate the traffic going between islands' Primary Nodes (PNs). AMT was used for its added benefits such as security and being better at traffic shaping and Quality Of Service (QoS). While different approaches for connecting multicast islands exists, the system proposed in the thesis was designed with the following characteristics in mind: scalability, availability, interoperability, self-adaptation and efficiency. Importantly, by utilising AMT tunnels, this approach has unique properties that improve network security and management.

The share of peer-to-peer (P2P) protocol in the total network traffic grows dayby- day in the Turkish Academic Network (UlakNet) similar to the other networks in the world. This growth is mostly because of the popularity of the shared content and the great enhancement in the P2P protocol since it first came out with Napster. The shared files are generally both large and copyrighted. Motivated by the problems of UlakNet with the P2P traffic, we propose a novel method for P2P traffic detection in the network backbone in this thesis. Observing the similarity between detecting traffic that belongs to a specific protocol and detecting an intrusion in a computer system, we adopt an Intrusion Detection System (IDS) technique to detect P2P traffic. Our method is a passive detection procedure that uses traffic flows gathered from border routers. Hence, it is scalable and does not have the problems of other approaches that rely on packet payload data or transport layer ports.

Le réseau de distribution et de transport de l’électricité se modernise dans plusieurs pays dont le Canada. La nouvelle génération de ce réseau que l’on appelle smart grid, permet entre autre l’automatisation de la production, de la distribution et de la gestion de la charge chez les clients. D’un autre côté, des appareils domestiques intelligents munis d’une interface de communication pour des applications du smart grid commencent à apparaître sur le marché. Ces appareils intelligents pourraient créer une communauté virtuelle pour optimiser leurs consommations d’une façon distribuée. La gestion distribuée de ces charges intelligentes nécessite la communication entre un grand nombre d’équipements électriques. Ceci représente un défi important à relever surtout si on ne veut pas augmenter le coût de l’infrastructure et de la maintenance. Lors de cette thèse deux systèmes distincts ont été conçus : un système de communication peer-to-peer, appelé Ring-Tree, permettant la communication entre un nombre important de nœuds (jusqu’à de l’ordre de grandeur du million) tel que des appareils électriques communicants et une technique distribuée de gestion de la charge sur le réseau électrique. Le système de communication Ring-Tree inclut une nouvelle topologie réseau qui n’a jamais été définie ou exploitée auparavant. Il inclut également des algorithmes pour la création, l’exploitation et la maintenance de ce réseau. Il est suffisamment simple pour être mis en œuvre sur des contrôleurs associés aux dispositifs tels que des chauffe-eaux, chauffage à accumulation, bornes de recharges électriques, etc. Il n’utilise pas un serveur centralisé (ou très peu, seulement lorsqu’un nœud veut rejoindre le réseau). Il offr une solution distribuée qui peut être mise en œuvre sans déploiement d’une infrastructure autre que les contrôleurs sur les dispositifs visés. Finalement, un temps de réponse de quelques secondes pour atteindre l’ensemble du réseau peut être obtenu, ce qui est suffisant pour les besoins des applications visées. Les protocoles de communication s’appuient sur un protocole de transport qui peut être un de ceux utilisés sur l’Internet comme TCP ou UDP. Pour valider le fonctionnement de de la technique de contrôle distribuée et le système de communication Ring-Tree, un simulateur a été développé; un modèle de chauffe-eau, comme exemple de charge, a été intégré au simulateur. La simulation d’une communauté de chauffe-eaux intelligents a montré que la technique de gestion de la charge combinée avec du stockage d’énergie sous forme thermique permet d’obtenir, sans affecter le confort de l’utilisateur, des profils de consommation variés dont un profil de consommation uniforme qui représente un facteur de charge de 100%.

Made available in DSpace on 2014-06-12T15:59:37Z (GMT). No. of bitstreams: 2 arquivo5349_1.pdf: 1338520 bytes, checksum: 967ea568492e0071544a3a6f547aed59 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / A TV Digital Interativa traz consigo uma série de mudanças que vai muito além da melhoria de qualidade em áudio e vídeo. Ela trará o aumento da diversidade e disponibilidade de conteúdo multimídia e fará com que as pessoas deixem de ser meros espectadores para se tornarem também usuários de aplicativos multimídia interativos. Estes aplicativos virão com o conteúdo multimídia e irão permitir que o usuário possa interagir ativamente com o conteúdo exibido ou até mesmo com as emissoras, pois os padrões de TV digital prevêem a existência de um canal de interação através do qual o aparelho de TV possa se comunicar numa rede de computadores, como a Internet, por exemplo. Desta forma, as aplicações de TV digital poderão acessar serviços como e-mail, Internet-banking e comércio eletrônico. No entanto, estes são serviços centralizados e não exploram a interatividade entre as pessoas. É fácil prever que, num futuro próximo, existirá demanda por aplicações que explorem a interatividade entre as pessoas. Porém, fazer com que estas aplicações se comuniquem é um verdadeiro desafio, pois o uso de servidores para intermediar mensagens está sujeito a problemas de escalabilidade, e a troca direta de mensagens é prejudicada pela heterogeneidade da rede em que o canal de interação é disponibilizado. Este trabalho propõe um Middleware para este tipo de aplicação distribuída. O Middleware proposto foi baseado no modelo de comunicação peer-to-peer, pois, após a análise dos requisitos deste tipo de software distribuído, verificou-se que este modelo é o que melhor se adequa. O mesmo foi construído sobre a plataforma JXTA, que resolve os problemas de infra-estrutura da rede, compreendendo um serviço avançado de busca e um mecanismo de invocação remota de método, semelhante à tecnologia Java RMI

Avec l'évolution des réseaux fixes et mobiles, des terminaux de plus en plus nombreux et diversifiés, il est maintenant possible d'accéder à n'importe quel type de service, depuis n'importe quel type de terminal, en étant connecté sur n'importe quel type de réseau. En ajoutant le souhait des utilisateurs de recevoir un contenu personnalisé, l'adaptation de contenu est devenue une problématique majeure. Cette thèse définit une solution de noeud intermédiaire, flexible permettant l'adaptation dynamique de tout type de contenu en fonction du contexte de l'utilisateur. Ces travaux ont abouti à la définition d'une architecture de noeud, dénommé Potacco pour noeud POlymorphique Transparent pour l'Adaptation de Contenu adapté au COntexte, à sa mise en oeuvre et sa validation. Ce noeud : * collecte et met à disposition le contexte courant pour permettre aux modules applicatifs de réaliser des adaptations en fonction de ces valeurs * gère/coordonne les modules applicatifs et les collecteurs de contexte * permet le déploiement sécurisé de code dans le noeud avec authentification du fournisseur du code, mais aussi du noeud cible * peut être transparent en réalisant des traitements sans que les points terminaux puissent s'en apercevoir. Deux démonstrateurs constituent une preuve de concept de ce noeud générique, intégré dans un réseau physique: une passerelle filaire/sans-fil réalisant l'adaptation de contenu média et un noeud dans un réseau ADSL insérant dynamiquement le contexte des utilisateurs. Ensuite, l'apport de ce noeud dans le cadre des réseaux "overlays" a fait l'objet d'une nouvelle preuve de concept. Deux cas ont été étudiés: la première pour la fourniture de service adapté au contexte de l'utilisateur dans un réseau overlay de service, où un cas d'usage de service d'IPTV personnalisé est présenté; la deuxième relative à l'adaptation de contenu de flux multimédia diffusé sur un réseau P2P où le noeud Potacco est lui-même membre du réseau P2P. Des évaluations, par simulation et expérimentation réelle, ont permis d'évaluer ces solutions.

Living in an increasingly networked world, with an abundant number of services available to consumers, the consumer electronics market is enjoying a boom. The average consumer in the developed world may own several networked devices such as games consoles, mobile phones, PDAs, laptops and desktops, wireless picture frames and printers to name but a few. With this growing number of networked devices comes a growing demand for services, defined here as functions requested by a client and provided by a networked node. For example, a client may wish to download and share music or pictures, find and use printer services, or lookup information (e.g. train times, cinema bookings). It is notable that a significant proportion of networked devices are now mobile. Mobile devices introduce a new dynamic to the service discovery problem, such as lower battery and processing power and more expensive bandwidth. Device owners expect to access services not only in their immediate proximity, but further afield (e.g. in their homes and offices). Solving these problems is the focus of this research. This Thesis offers two alternative approaches to service discovery in Wide Area Networks (WANs). Firstly, a unique combination of the Session Initiation Protocol (SIP) and the OSGi middleware technology is presented to provide both mobility and service discovery capability in WANs. Through experimentation, this technique is shown to be successful where the number of operating domains is small, but it does not scale well. To address the issue of scalability, this Thesis proposes the use of Peer-to-Peer (P2P) service overlays as a medium for service discovery in WANs. To confirm that P2P overlays can in fact support service discovery, a technique to utilise the Distributed Hash Table (DHT) functionality of distributed systems is used to store and retrieve service advertisements. Through simulation, this is shown to be both a scalable and a flexible service discovery technique. However, the problems associated with P2P networks with respect to efficiency are well documented. In a novel approach to reduce messaging costs in P2P networks, multi-destination multicast is used. Two well known P2P overlays are extended using the Explicit Multi-Unicast (XCAST) protocol. The resulting analysis of this extension provides a strong argument for multiple P2P maintenance algorithms co-existing in a single P2P overlay to provide adaptable performance. A novel multi-tier P2P overlay system is presented, which is tailored for service rich mobile devices and which provides an efficient platform for service discovery.