Le but de cette thèse est de proposer des mécanismes efficaces pour l'ordonnancement des chunks et l'allocation de la bande passante dans le contexte de la transmission vidéo sur les réseaux P2P,afin d'offrir une meilleure qualité de service pour l'utilisateur final. Dans un premier temps nousavons proposé un mécanisme d'ordonnancement des chunks pour la transmission de vidéomulticouche dans les réseaux P2P. Le mécanisme proposé est basé sur une nouvelle technique quipermet de sélectionner les chunks adéquats et les demander des pairs les plus appropriés. Ensuitenous avons proposé un mécanisme d'allocation de la bande passante, toujours dans le cadre detransmission de vidéo multicouche dans les réseaux P2P. Le pair émetteur organise une enchère pour«vendre » sa bande passante. L'allocation tient en considération la priorité des pairs et l'importancedes couches demandées. Finalement nous avons proposé un mécanisme d'adaptation lisse « smooth» d'une vidéo multicouche transportée sur un réseau P2P.Après une introduction, nous présentons dans le chapitre 2 les motivations du travail le but du travailet les problèmes recherche qui demeurent. Dans ce chapitre nous présentons les composants dessystèmes P2P et tout particulièrement la distribution et l'adaptation de contenus. Dans ce cadre,nous proposons une classification des applications de streaming vidéo P2P ainsi que des mécanismesd'allocation de bande passante et d'ordonnancement pour le streaming pair-à-pair. Nous nousintéressons également aux techniques d'adaptation de la qualité en se focalisant plusparticulièrement sur la norme SVC (Scalable Video Coding).Le chapitre 3 propose des mécanismes de priorisation pour la planification de streaming P2P multicouches.Nous proposons une heuristique pour résoudre un problème général d'affectationgénéralisé (Generalized Assignment Problem – GAP). La solution présentée est ensuite adaptée aucas du streaming non multicouches. Les résultats issus des simulations montrent que les solutionsproposées donnent de meilleurs résultats que les solutions traditionnelles.Le chapitre 4 décrit un mécanisme d'allocation dynamique de la bande passante pour les réseaux destreaming P2P multicouches qui se base sur l'allocation d'une bande passante aux pairs tout enassurant un minimum de qualité de service à l'ensemble des pairs. Les bonnes performances desmécanismes proposés, qui sont détaillées à travers l'étude du ratio concernant l'utilisation de labande passante ainsi que du niveau de satisfaction des pairs, montrent que ces derniers permettentd'obtenir une utilisation optimale de la bande passante.Le chapitre 5 porte sur le lissage du streaming multicouches dans les réseaux P2P en se basant sur lesmétriques liées à la variation de la fréquence et de l'amplitude. Les mécanismes proposés ont étéimplémentés dans un banc d'essai réel et l'évaluation des performances montrent l'efficacité desmécanismes pour le lissage du streaming.Dans le chapitre 6 (conclusion and perspectives), nous résumons les contributions proposées danscette thèse ainsi qu’une ouverture sur les travaux futures / Recently we witnessed an increasing demand for scalable deployment of real-time multimediastreaming applications over Internet. In this context, Peer-to-Peer (P2P) networks are playing asignificant role for supporting large-scale and robust distribution of multimedia content to end-users.However, due to peers’ dynamicity, heterogeneity of terminals and access networks, the deploymentof real-time video streaming applications over P2P networks arises lot of challenges. Indeed, animportant issue in P2P overlays is the capacity to self-organize in the face of the dynamic behavior ofpeers in order to ensure content availability and continuity. In addition, the heterogeneity in networks,terminals, and P2P characteristics make the situation more challenging. In this context, layered videostreaming in P2P networks has drawn great interest to overcome these challenges, since it can notonly accommodate large numbers of users, but also handle heterogeneity of peers. However, there isstill a lack of comprehensive studies on video data blocks (chunks) scheduling and bandwidthallocation for the smooth playout in layered streaming over P2P networks.The aim of this thesis is to analyze these concerns and to propose an efficient real-time chunksscheduling and bandwidth allocation mechanisms for QoS provisioning of layered streamingapplications over P2P networks. Our contributions in this thesis are threefold. First, we propose ascheduling mechanism for layered P2P streaming. The proposed mechanism relies on a novelscheduling algorithm that enables each peer to select appropriate stream layers, along withappropriate peers to provide them. The presented mechanism makes efficient use of networkresources and provides high system throughput. Second, we propose a bandwidth allocation modelfor P2 layered streaming systems based on auction mechanisms to optimize the allocation of senderpeers’ uploads bandwidth. The upstream peers organize auctions to “sell” theirs items (links’bandwidth) according to bids submitted by the downstream peers taking into consideration the peerspriorities and the requested layers importance. The ultimate goal is to satisfy the quality levelrequirement for each peer, while reducing the overall streaming cost. Finally, we present a smoothingmechanism for layered streaming in P2P networks. The mechanism aims to reduce the number oflayer changes under varying network conditions, and ensure a smooth playout for the end-user.

Dans cette thèse, nous nous intéressons à l’application du codage réseau pour garantir la qualité de service (QoS) dans les réseaux sans fil multi-sauts. Comme le support de transmission est partagé, les réseaux sans fil souffrent de l’impact négatif des interférences sur la bande passante. Il est alors intéressant de proposer une approche basée sur le codage réseau qui prenne en compte ces interférences durant le processus de routage. Dans ce contexte, nous proposons d’abord un algorithme minimisant l’impact des interférences pour des flux unicast tout en respectant la bande passante qu’ils exigent. Puis, nous le combinons avec le codage réseau afin d’augmenter le nombre des flux acceptés et avec le contrôle de topologie pour améliorer davantage la gestion des interférences. Nous montrons par simulation l’intérêt de combiner les trois domaines : codage réseau, gestion des interférences et contrôle de topologie. Nous abordons également la gestion du délai pour les flux multicast et utilisons le codage réseau basé sur les générations (GBNC) qui combine les paquets par bloc. La plupart des travaux portant sur le GBNC considèrent une taille de génération fixe mais à cause des variations de l’état du réseau le délai de décodage et de récupération du bloc de paquets peut varier, dégradant la QoS. Pour résoudre ce problème, nous proposons une méthode qui ajuste la taille de la génération de façon dynamique pour respecter un certain délai de décodage avec prise en compte des contextes réseau et contenu. De plus, nous améliorons notre approche pour contrecarrer les pertes des acquittements. Puis, nous proposons de l’utiliser dans un réseau de domicile pour la diffusion de vidéo à la demande. Notre solution améliore la QoS et la qualité d’expérience pour l’utilisateur final sans équipement additionnel. Finalement, nous abordons un sujet plus théorique dans lequel nous présentons un nouveau réseau basé sur le schéma Butterfly pour des flux multi-sources multi-destinations. Nous caractérisons la taille du buffer du nœud source en utilisant la théorie des files d’attente et montrons qu’elle correspond aux résultats de simulation. / In this thesis we deal with the application of Network Coding to guarantee the Quality of Service (QoS) for wireless multi-hop networks. Since the medium is shared, wireless networks suffer from the negative interference impact on the bandwidth. It is thus interesting to propose a Network Coding based approach that takes into account this interference during the routing process. In this context, we first propose an algorithm minimizing the interference impact for unicast flows while respecting their required bandwidth. Then, we combine it with Network Coding to increase the number of admitted flows and with Topology Control to still improve the interference management. We show by simulation the benefit of combining the three fields: Network Coding, interference consideration and Topology Control. We also deal with delay management for multicast flows and use the Generation-Based Network Coding (GBNC) that combines the packets per blocks. Most of the works on GBNC consider a fixed generation size. Because of the network state variations, the delay of decoding and recovering a block of packets can vary accordingly degrading the QoS. To solve this problem, we propose a network-and content-aware method that adjusts the generation size dynamically to respect a certain decoding delay. We also enhance it to overcome the issue of acknowledgement loss. We then propose to apply our approach in a Home Area Network for Live TV and video streaming. Our solution provides QoS and Quality of Experience for the end user with no additional equipment. Finally, we focus on a more theoretical work in which we present a new Butterfly-based network for multi-source multi-destination flows. We characterize the source node buffer size using the queuing theory and show that it matches the simulation results.

Since the field of computer networks has rapidly grown in the last two decades, congestion control of traffic loads within networks has become a high priority. Congestion occurs in network routers when the number of incoming packets exceeds the available network resources, such as buffer space and bandwidth allocation. This may result in a poor network performance with reference to average packet queueing delay, packet loss rate and throughput. To enhance the performance when the network becomes congested, several different active queue management (AQM) methods have been proposed and some of these are discussed in this thesis. Specifically, these AQM methods are surveyed in detail and their strengths and limitations are highlighted. A comparison is conducted between five known AQM methods, Random Early Detection (RED), Gentle Random Early Detection (GRED), Adaptive Random Early Detection (ARED), Dynamic Random Early Drop (DRED) and BLUE, based on several performance measures, including mean queue length, throughput, average queueing delay, overflow packet loss probability, packet dropping probability and the total of overflow loss and dropping probabilities for packets, with the aim of identifying which AQM method gives the most satisfactory results of the performance measures. This thesis presents a new AQM approach based on the RED algorithm that determines and controls the congested router buffers in an early stage. This approach is called Dynamic RED (REDD), which stabilises the average queue length between minimum and maximum threshold positions at a certain level called the target level to prevent building up the queues in the router buffers. A comparison is made between the proposed REDD, RED and ARED approaches regarding the above performance measures. Moreover, three methods based on RED and fuzzy logic are proposed to control the congested router buffers incipiently. These methods are named REDD1, REDD2, and REDD3 and their performances are also compared with RED using the above performance measures to identify which method achieves the most satisfactory results. Furthermore, a set of discrete-time queue analytical models are developed based on the following approaches: RED, GRED, DRED and BLUE, to detect the congestion at router buffers in an early stage. The proposed analytical models use the instantaneous queue length as a congestion measure to capture short term changes in the input and prevent packet loss due to overflow. The proposed analytical models are experimentally compared with their corresponding AQM simulations with reference to the above performance measures to identify which approach gives the most satisfactory results. The simulations for RED, GRED, ARED, DRED, BLUE, REDD, REDD1, REDD2 and REDD3 are run ten times, each time with a change of seed and the results of each run are used to obtain mean values, variance, standard deviation and 95% confidence intervals. The performance measures are calculated based on data collected only after the system has reached a steady state. After extensive experimentation, the results show that the proposed REDD, REDD1, REDD2 and REDD3 algorithms and some of the proposed analytical models such as DRED-Alpha, RED and GRED models offer somewhat better results of mean queue length and average queueing delay than these achieved by RED and its variants when the values of packet arrival probability are greater than the value of packet departure probability, i.e. in a congestion situation. This suggests that when traffic is largely of a non bursty nature, instantaneous queue length might be a better congestion measure to use rather than the average queue length as in the more traditional models.

The promise of service oriented computing, and the availability of Web services promote the delivery and creation of new services based on existing services, in order to meet new demands and new markets. As Web and internet based services move into Clouds, inter-dependency of services and their complexity will increase substantially. There are standards and frameworks for specifying and composing Web Services based on functional properties. However, mechanisms to individually address non-functional properties of services and their compositions have not been well established. Furthermore, the Cloud ontology depicts service layers from a high-level, such as Application and Software, to a low-level, such as Infrastructure and Platform. Each component that resides in one layer can be useful to another layer as a service. It hints at the amount of complexity resulting from not only horizontal but also vertical integrations in building and deploying a composite service. To meet the requirements and facilitate using Web services, we first propose a WSDL extension to permit specification of non-functional or Quality of Service (QoS) properties. On top of the foundation, the QoS-aware framework is established to adapt publicly available tools for Web services, augmented by ontology management tools, along with tools for performance modeling to exemplify how the non-functional properties such as response time, throughput, or utilization of services can be addressed in the service acquisition and composition process. To facilitate Web service composition standards, in this work we extended the framework with additional qualitative information to the service descriptions using Business Process Execution Language (BPEL). Engineers can use BPEL to explore design options, and have the QoS properties analyzed for the composite service. The main issue in our research is performance evaluation in software system and engineering. We researched the Web service computation as the first half of this dissertation, and performance antipattern detection and elimination in the second part. Performance analysis of software system is complex due to large number of components and the interactions among them. Without the knowledge of experienced experts, it is difficult to diagnose performance anomalies and attempt to pinpoint the root causes of the problems. Software performance antipatterns are similar to design patterns in that they provide what to avoid and how to fix performance problems when they appear. Although the idea of applying antipatterns is promising, there are gaps in matching the symptoms and generating feedback solution for redesign. In this work, we analyze performance antipatterns to extract detectable features, influential factors, and resource involvements so that we can lay the foundation to detect their presence. We propose system abstract layering model and suggestive profiling methods for performance antipattern detection and elimination. Solutions proposed can be used during the refactoring phase, and can be included in the software development life cycle. Proposed tools and utilities are implemented and their use is demonstrated with RUBiS benchmark.

L’Internet des Objets (IoT) est déjà omniprésent aujourd’hui : domotique, bâtiments connectés ou ville intelligente, beaucoup d’initiatives et d’innovations sont en cours et à venir. Le nombre d’objets connectés ne cesse de croître à tel point que des milliards d’objets sont attendus dans un futur proche.L’approche de cette thèse met en place un système de gestion autonomique pour des systèmes à base d’objets connectés, en les combinant avec d’autres services comme par exemple des services météo accessibles sur internet. Les modèles proposés permettent une prise de décision autonome basée sur l’analyse d’évènements et la planification d’actions exécutées automatiquement. Des paramètres comme le temps d’exécution ou l’énergie consommée sont aussi considérés afin d’optimiser les choix d’actions à effectuer et de services utilisés. Un prototype concret a été réalisé dans un scénario de ville intelligente et de bus connectés dans le projet investissement d'avenir S2C2. / The Internet of Things (IoT) is already everywhere today: home automation, connected buildings or smart city, many initiatives and innovations are ongoing and yet to come. The number of connected objects continues to grow to the point that billions of objects are expected in the near future.The approach of this thesis sets up an autonomic management architecture for systems based on connected objects, combining them with other services such as weather services accessible on the Internet. The proposed models enable an autonomous decision making based on the analysis of events and the planning of actions executed automatically. Parameters such as execution time or consumed energy are also considered in order to optimize the choices of actions to be performed and of services used. A concrete prototype was realized in a smart city scenario with connected buses in the investment for future project: S2C2.

Pour faire face aux enjeux d’une économie mondialisée, aux fluctuations du marché et aux changements de la demande (personnalisation massive, qualité…), les entreprises recourent de plus en plus aux stratégies de collaboration et d’organisation en réseau et adoptent des stratégies orientées « produit/service ». Cette tendance est renforcée par le développement des applications du Web 2.0 (voire 3.0?) et l’adoption d’architectures orientées services permettant d’augmenter l’interopérabilité et l’agilité des systèmes d’information. En outre, les possibilités offertes par le Cloud Computing permet de rendre le déploiement plus flexible. En parallèle, le développement de stratégies industrielles comme le « lean manufacturing » et le 6-Sigmas permet d’améliorer les procédés, l’organisation industrielle elle-même et la qualité des produits. L’objectif de ce travail de recherche est de coupler la vision « industrielle » à la vision « système d’information » traditionnelle pour permettre de mettre en place un modèle de services industriels composables, orchestrables et « gouvernables ». Pour cela, nous proposons de mettre en place une architecxture de gouvernance globale « connectant » les différentes couches du système (métier/industriel, service, plateforme et infrastructure), permettant d’améliorer la gouvernance du système globale (en évitant les incohérences liées à une prise en compte et une optimisation « isolée » des différents facteurs de performance) tant au niveau organisationnel que technologique. Ceci pourrait permettre d’améliorer les performances tant au niveau « métier » que « technologique », augmenter l’agilité du système et supporter plus efficacement les stratégies de collaboration en développant une approche basée sur la sélection / composition / orchestration de services métier industriels. / Due to the renewed globalised economical environment and the market evolution (mass customization, sustainability requirements…) the call for developing product-service strategy becomes a major stake, leading industrial companies to set collaborative business organizations and develop business services. This trend has been favored by the large-scale IT environment provided by the web 2.0 and by the development of interoperable and rather agile IT technologies based on services leading to SOA-based information systems reorganization. At the same time, lean and six sigma theories have also been used in industries to improve the industrial process itself so that profitability, quality and reputation are increased. As a new economical and technical model, Cloud Computing has generated a tremendous amount of interest and excitement in recent years as it gives a new and useful way to address IT challenges To achieve the primary goals of these technologies, concepts and models, an efficient industrial organization governance method is necessary. We propose a flexible, efficient, low cost monitoring strategy, it can couple the different layers of economic ecosystem (including business strategies, business/industrial/IT services, execution platforms and infrastructure means) it can overcome existing industrial governance architectures’ limits (most of them are rather “fixed” and lack agility, overall perspective governance as they have unilateral perspective), and it could drive the industry towards better practices, improve ability of enterprises to cope with changes from both a technical and an organizational point of view, as well as reinforce external and internal collaborative work of enterprises.

Molntjänster spelar en betydande roll i dagens samhälle och används i såväl den privata sektorn som den offentliga. I och med den utbredda användningen har det ur ett organisationsperspektiv uppstått ett behov att utvärdera tjänsterna. Denna undersökning behandlar hur företags val av molntjänster går till i praktiken, vilka krav företag ställer på molntjänster, vilka krav företag anser vara viktigast, samt hur väl molntjänster lyckas bemöta dessa krav. Undersökningen utfördes genom intervjuer och en kvalitativ analys av tre företags situationer gällande molntjänster. Sammanfattningsvis dras slutsatsen att företagens val av molntjänstleverantör beror på en kombination av lock-ins och tidigare uppfattning av leverantören. Det visade sig att krav på säkerhet och foglighet var viktigast för alla tre företag, och att alla tre även rangordnat pålitlighet och tillförlitlighet som näst viktigast. Därefter skiljer sig rangordningen av kraven något mellan företagen, vilket bland annat beror på att deras kunder har olika krav på diverse faktorer. Vad gäller bemötandet av kraven från leverantören visade det sig att alla tre företag generellt upplever en stor nöjdhet för samtliga krav.

Este projeto de doutorado tem como objetivo definir modelos de negócio para ambientes de computação em nuvem que consideram desempenho e segurança como atributos de qualidade de serviço durante a definição do contrato. Para isso, foi necessário quantificar o impacto causado no desempenho de um ambiente em nuvem quando diferentes mecanismos de segurança foram utilizados. Para a quantificação da sobrecarga foram utilizadas técnicas e metodologias disponíveis na literatura que visam garantir a integridade, disponibilidade e confidencialidade dos dados, abordando desafios que envolvem o acesso, armazenamento e manipulação de dados em serviços oferecidos por meio de máquinas virtuais. Experimentos executados possibilitaram analisar o comportamento das variáveis de resposta na utilização de cenários com diferentes mecanismos de segurança e cargas. Dessa forma, foi possível confrontar a sobrecarga imposta pelos mecanismos de segurança com a alteração da quantidade de recursos aplicada por um módulo proposto, chamado ReMM. De acordo com os resultados, o ReMM alterou a quantidade de recursos virtuais alocados utilizando dois algoritmos de escalabilidade, garantindo as exigências definidas no contrato de níveis de serviço. No entanto, a alteração dos recursos computacionais para contrapor a sobrecarga imposta pelos mecanismos de segurança impactou nos custos finais dos serviços. Dessa forma, a sobrecarga de segurança, desempenho e custo foram considerados na definição dos modelos de negócios em diferentes ambientes de computação em nuvem. / This PhD thesis has as main goal defining business models for cloud computing environments that consider performance and security as quality of service attributes during the service level agreement definition. For this, it was necessary quantifying the impact on the performance of a cloud environment in which different security mechanisms were applied. Techniques and methodologies available in the literature that aim ensuring the integrity, availability and confidentiality of data were used to quantify the overhead, addressing challenges related to access, storage and manipulation of data in services offered through virtual machines. Experiments were executed, in which the response variable behaviors were analyzed, using scenarios with different security mechanisms and workloads. In this way, it was possible to compare the overhead imposed by the security mechanisms with the changes in the quantity of resources applied by a module proposed, called ReMM. According to the results, the ReMM changed the amount of allocated virtual resources using two scalability algorithms, ensuring the requirements defined in service level agreement. However, the changes in the computational resources to face the overhead imposed by the security mechanisms influenced the final costs of the service. Therefore, security overhead, performance and cost were considered in the definition of business models in different cloud computing environments.

Um estudo sobre as principais causas de quedas de chamadas em célula de rede móvel GSM é realizado por meio da análise estatística do tráfego. O objetivo é minimizar o efeito dessas causas, por meio da alteração de parâmetros de cobertura, como controle dinâmico de potência, borda de cobertura entre células e definição correta de células vizinhas. Para uma operadora celular reduzir a taxa de queda de chamadas (TQC), por intermédio da otimização de parâmetros de cobertura, alterados via comandos remotos, elimina os custos com alterações físicas, como altura das antenas e instalações de novas estações rádio base. Entretanto, alterações de parâmetros devem ser cuidadosamente realizadas, pois podem degradar outros indicadores e acarretar redução da área de cobertura e do tráfego. As duas principais causas da TQC são as quedas repentinas, ocasionadas por falha nos equipamentos envolvidos, ou comportamento dos assinantes e falha na execução do handover e as quedas devido ao nível baixo de sinal na interface aérea. Neste trabalho, com base em dados estatísticos do tráfego na rede GSM, foi escolhida uma célula operando em 900 MHz que apresentava alta TQC. Ajustando os parâmetros de cobertura, a TQC mensal passou de 8,6% para 1,6% e não houve degradação nos demais indicadores de desempenho. / A study about the main causes of dropped calls in mobile network cell GSM is made by means of statistical traffic analysis. The aim is to minimize the effect of these causes through coverage parameters changes, such as dynamical potency control, coverage border between cells, correct definition of neighboring cells. The reduction of dropped call rate by means of optimization of coverage parameters, changed via remote commands, eliminates costs with physical changes, such as the height of the antennas and installation of new radio base station. Parameter changes, however, must be carefully made because they can degrade other indicators and bring coverage area and traffic reduction. The two main causes of dropped call are sudden loss of connection, due to failure in the equipment used, behavior of subscribers and the failure in handover and drops due to the low signal strength in the air interface. In this study, based on statistical data of GSM traffic, a cell operating in 900 MHz that presented high dropped call rate was chosen. Adjusting the coverage parameters, the monthly dropped call rate went from 8.6% to 1.6% and there wasn\'t any degradation of any other performance indicators.

A economia globalizada e os avanços tecnológicos propiciaram um novo modelo de Outsourcing de Tecnologia de Informação (TI): os provedores de serviços de aplicativos (ASP - Application Service Providers). As discussões a respeito de ASP intensificaram-se nos três últimos anos, com a proposta de comercialização do software como um serviço. Quanto maior a interdependência da área de TI com as metas de negócios das organizações, maior a ênfase dada à satisfação das expectativas do cliente quanto aos serviços prestados pelos provedores. No mercado, têm-se adotado os acordos dos níveis de serviços (SLA - Service Level Agreements) como mecanismo de controle das atividades de outsourcing. Porém, essa adoção é nova e imatura, e a literatura é escassa. Tanto os provedores quanto os cliente sentem a necessidade por estruturas de implantação semelhantes às de SLA. Essa carência é ressaltada no caso dos modelos ASP. Propondo-se a contribuir com a compressão do modelo ASP e de SLA para ASP, apresenta-se uma pesquisa exploratória das características desse modelo com SLA, de modelos de qualidade de serviços de outsourcing e finalmente de considerações que devem ser feitas para garantir a qualidade dos serviços ASP, empregando-se os SLA. / The global economy and technological advances propitiated a new model of Information Technology (IT) Outsourcing: the Application Service Providers - ASP. Discussions regarding ASP became more frequent in the last three years because of the new approach of selling software as a service. As the interdependency between the IT area and the business goals of organizations becomes greater, the emphasis on fulfilling the client\'s expectations regarding service rendered by providers becomes stronger. In the market, Service Level Agreements - SLA have been adopted as control mechanisms of outsourcing activities. However, this adoption is new and immature, and the literature on the matter is scarce. Providers and clients feel the need for implementation structures similar to SLA\'s. In lhe case of ASP models, this necessity is emphasized mainly due to the lack of conceptual information on the ASP model. In order to better comprehend lhe ASP and the SLA models for ASP, I am presenting an exploratory research about the characteristics of the new approach with SLA models, outsourcing models of service quality and considerations, which must be carried out to ensure quality of ASP services employing SLA.