Η παρούσα διατριβή κινείται στο χώρο των Ασύρματα Δικτυωμένων Συστημάτων και έχει ως αντικείμενο τη μελέτη και τη σύνθεση μηχανισμών που βελτιώνουν τη λειτουργία τους. Ο όρος Ασύρματα Δικτυωμένα Συστήματα αναφέρεται στα συστήματα των οποίων τα δομικά στοιχεία συνδέονται μέσω ασύρματων δικτύων, με την έμφαση να δίνεται στα αυτό-οργανωμένα δίκτυα και στα δίκτυα αισθητήρων. Η βελτιστοποίηση και ο έλεγχος ενός Ασύρματα Δικτυωμένου Συστήματος γίνεται με γνώμονα την Ποιότητα των παρεχόμενων Υπηρεσιών του δικτύου, η οποία χρησιμοποιείται ως μέτρο αξιολόγησης και επαναπροσδιορισμού των παραμέτρων λειτουργίας αυτού. Προσεγγίζοντας το θέμα από την οπτική γωνία του δικτύου, οι μηχανισμοί που είναι υπεύθυνοι για τη βελτιστοποίηση της λειτουργίας των Ασύρματα Δικτυωμένων Συστημάτων, αποστασιοποιούνται από την ανάπτυξη νέων πρωτοκόλλων για τα διάφορα επίπεδα του μοντέλου αναφοράς Ανοιχτής Διασύνδεσης Συστημάτων. Για τον λόγο αυτό, αναφορικά με το μοντέλο αναφοράς Ανοιχτής Διασύνδεσης Συστημάτων, το ζήτημα της βελτιστοποίησης της λειτουργίας των Ασύρματα Δικτυωμένων Συστημάτων προσεγγίζεται από τα ακραία επίπεδα της στοίβας πρωτοκόλλων, και συγκεκριμένα από την οπτική γωνία του Επιπέδου Εφαρμογής και του Φυσικού Επιπέδου. Στο Επίπεδο Εφαρμογής το ενδιαφέρον επικεντρώνεται στην διασφάλιση των περιθωρίων ευστάθειας για τα Ασύρματα Δικτυωμένα Συστήματα Ελέγχου. Η διασφάλιση της ομαλής λειτουργίας του συστήματος κλειστού βρόχου βασίζεται σε διακοπτικές δομές ελέγχου, των οποίων οι παράμετροι λειτουργίας καθορίζονται από την Ποιότητα Υπηρεσίας του δικτύου, και συγκεκριμένα από το ποσοστό των επιτυχώς ληφθέντων πακέτων. Στο Φυσικό Επίπεδο εξετάζεται αρχικά το πρόβλημα αποκατάστασης της συνδεσιμότητας μεταξύ των μελών ενός Ασύρματα Δικτυωμένου Συστήματος και στην συνέχεια το πρόβλημα επαναπροσδιορισμού της ποιότητας των ασύρματων ζεύξεων. Οι κεντρικοποιημένοι και κατανεμημένοι μηχανισμοί που αναπτύσσονται για τη βελτιστοποίηση των παραμέτρων της Ποιότητας Υπηρεσίας των Ασύρματα Δικτυωμένων Συστημάτων στο Φυσικό Επίπεδο βασίζονται σε εργαλεία της Υπολογιστικής Γεωμετρίας, συνδυάζοντας τα χωρικά χαρακτηριστικά ενός Ασύρματα Δικτυωμένου Συστήματος με δημοφιλή μοντέλα διάδοσης μεγάλης κλίμακας. Τέλος, η αξιολόγηση των μεθόδων ελέγχου και βελτιστοποίησης της λειτουργίας των Ασύρματα Δικτυωμένων Συστημάτων πραγματοποιείται με την εφαρμογή τους σε κατάλληλες πειραματικές διατάξεις και σε ένα καθορισμένο σύνολο σεναρίων εξομοίωσης. / The primary objective of the present PhD thesis is the analysis and the synthesis of mechanisms and algorithms that optimize the operation of Wireless Networked Systems. The term Wireless Networked Systems is used to describe the distributed systems, whose components are interconnected over wireless networks. Referring to wireless networking, the emphasis is given at the self-organized Ad-hoc and Sensor Networks. The effort made is focused on the reconfiguration of the Quality of Service of the underlying network. From such a perspective, the mechanisms responsible for improving the Quality of Service differentiate from the design of novel, specialized communication protocols. More specifically, with respect to the Open Systems Interconnection Reference Model (OSI-RM), the optimization issues of the Wireless Networked Systems’ operation are examined at the Application and Physical Layer. At the Application Layer, problems related to the guarantee of the stability margins for Wireless Networked Controlled Systems are studied. More precisely, the assurance of the desired performance for the closed-loop controlled system is based on switching control techniques. The optimization decision variables are determined by the network’s Quality of Service parameters. At the Physical Layer the objective is twofold: (a) to establish the physical connectivity among the members of the Wireless Networked System and (b) to optimize of the wireless link’s quality. Based on the combination of the spatial characteristics of the Wireless Networked Systems with large-scale radio propagation models, the centralized and distributed mechanisms, synthesized for the optimization of the network’s Quality of Service at the Physical Layer, exploit effectively concepts adopted by the Computational Geometry. Finally, properly developed experimental testbeds and network simulation scenaria are utilized to examine the efficiency of the synthesized mechanisms for the control and optimization of the operation of Wireless Networked Systems at the Application and Physical Layer.

L'objectif de ce travail de thèse dans un premier temps est l'évaluation de performances des modèles de routage multi-chemins pour l'ingénierie de trafic et l'équilibrage de charge sur un réseau de type IP/MPLS (MPLS-TE). Nous comparons la capacité de ces modèles à équilibrer la charge du réseau tout en faisant de la différentiation de trafic. Nous les appliquons sur des grandes topologies générées par le générateur automatique des topologies BRITE, qui s'approchent en forme et en complexité du réseau réel. Nous mesurons ainsi l'impact de leur complexité respective et donc la capacité à les déployer sur des réseaux de grande taille (scalabilité). Dans un second temps, l'objectif est de proposer un concept de modélisation générale d'un réseau à commutations par paquets. Ce modèle est établi sur la base de la théorie différentielle de trafic et la théorie des files d'attente, tout en utilisant des approches graphiques. Le but est d'estimer l'état de charge du réseau et de ses composants (routeurs, liens, chemins). Ensuite, en fonction de ça, nous développons des approches de contrôle de congestion et commande sur l'entrée améliorant les techniques de routage adaptatif et l'équilibrage de charge dans les réseaux IP/MPLS / In This work, firstly we present and evaluate the behavior of multipath routing models for the DS-TE (DiffSev aware MPLS traffic Engineering) called PEMS and LBWDP. To clarify network topologies and routing models that are suitable for MPLS Traffic Engineering, we evaluate them from the viewpoint of network scalability and end-to-end quality. Using a network topology generated by BRITE, that has many alternative paths, we applied these models on a huge topology that correspond to real network. This can provide a real simulation for the internet and gives a good evaluation for the end-to-end quality and the network use.Secondly, the aim of this work is to propose a general model for Packet switching networks. This model is established on the traffic differential theory and the Queuing theory, while using graphic approaches. The aim of this model is to calculate the network use state and its components (router, link, path...). Then, we develop control and command approaches in the entry of network to improve an adaptive routing plan and load balancing in IP/MPLS networks

Le « Cloud computing » est un nouveau modèle de systèmes de calcul. L’infrastructure, les applications et les données sont déplacées de machines localisées sur des systèmes dématérialisés accédés sous forme de service via Internet. Le modèle « coût à l’utilisation » permet des économies de coût en modifiant la configuration à l’exécution (élasticité). L’objectif de cette thèse est de contribuer à la gestion de la Qualité de Service (QdS) des applications s’exécutant dans le Cloud. Les services Cloud prétendent fournir une flexibilité importante dans l’attribution des ressources de calcul tenant compte des variations perçues, telles qu’une fluctuation de la charge. Les capacités de variation doivent être précisément exprimées dans un contrat (le Service Level Agreement, SLA) lorsque l’application est hébergée par un fournisseur de Plateform as a Service (PaaS). Dans cette thèse, nous proposons et nous décrivons formellement le langage de description de SLA PSLA. PSLA est fondé sur WS-Agreement qui est lui-même un langage extensible de description de SLA. Des négociations préalables à la signature du SLA sont indispensables, pendant lesquelles le fournisseur de PaaS doit évaluer la faisabilité des termes du contrat. Cette évaluation, par exemple le temps de réponse, le débit maximal de requêtes servies, etc, est fondée sur une analyse du comportement de l’application déployée dans l’infrastructure cloud. Une analyse du comportement de l’application est donc nécessaire et habituellement assurée par des tests (benchmarks). Ces tests sont relativement coûteux et une étude précise de faisabilité demande en général de nombreux tests. Dans cette thèse, nous proposons une méthode d’étude de faisabilité concernant les critères de performance, à partir d’une proposition de SLA exprimée en PSLA. Cette méthode est un compromis entre la précision d’une étude exhaustive de faisabilité et les coûts de tests. Les résultats de cette étude constituent le modèle initial de la correspondance charge entrante-allocation de ressources utilisée à l’exécution. Le contrôle à l’exécution (runtime control) d’une application gère l’allocation de ressources en fonction des besoins, s’appuyant en particulier sur les capacités de passage à l’échelle (scalability) des infrastructures de cloud. Nous proposons RCSREPRO (Runtime Control method based on Schedule, REactive and PROactive methods), une méthode de contrôle à l’exécution fondée sur la planification et des contrôles réactifs et prédictifs. Les besoins d’adaptation à l’exécution sont essentiellement dus à une variation de la charge soumise à l’application, variations difficiles à estimer avant exécution et seulement grossièrement décrites dans le SLA. Il est donc nécessaire de reporter à l’exécution les décisions d’adaptation et d’y évaluer les possibles variations de charge. Comme les actions de modification des ressources attribuées peuvent prendre plusieurs minutes, RCSREPRO réalise un contrôle prédictif fondée sur l’analyse de charge et la correspondance indicateurs de performance-ressources attribuées, initialement définie via des tests. Cette correspondance est améliorée en permanence à l’exécution. En résumé, les contributions de cette thèse sont la proposition de langage PSLA pour décrire les SLA ; une proposition de méthode pour l’étude de faisabilité d’un SLA ; une proposition de méthode (RCSREPRO) de contrôle à l’exécution de l’application pour garantir le SLA. Les travaux de cette thèse s’inscrivent dans le contexte du projet FSN OpenCloudware (www.opencloudware.org) et ont été financés en partie par celui-ci. / Cloud computing is a new computing model. Infrastructure, application and data are moved from local machines to internet and provided as services. Cloud users, such as application owners, can greatly save budgets from the elasticity feature, which refers to the “pay as you go” and on-demand characteristics, of cloud service. The goal of this thesis is to manage the Quality of Service (QoS) for applications running in cloud environments Cloud services provide application owners with great flexibility to assign “suitable” amount of resources according to the changing needs, for example caused by fluctuating request rate. “Suitable” or not needs to be clearly documented in Service Level Agreements (SLA) if this resource demanding task is hosted in a third party, such as a Platform as a Service (PaaS) provider. In this thesis, we propose and formally describe PSLA, which is a SLA description language for PaaS. PSLA is based on WS-Agreement, which is extendable and widely accepted as a SLA description language. Before signing the SLA contract, negotiations are unavoidable. During negotiations, the PaaS provider needs to evaluate if the SLA drafts are feasible or not. These evaluations are based on the analysis of the behavior of the application deployed in the cloud infrastructure, for instance throughput of served requests, response time, etc. Therefore, application dependent analysis, such as benchmark, is needed. Benchmarks are relatively costly and precise feasibility study usually imply large amount of benchmarks. In this thesis, we propose a benchmark based SLA feasibility study method to evaluate whether or not a SLA expressed in PSLA, including QoS targets, resource constraints, cost constraints and workload constraints can be achieved. This method makes tradeoff between the accuracy of a SLA feasibility study and benchmark costs. The intermediate of this benchmark based feasibility study process will be used as the workload-resource mapping model of our runtime control method. When application is running in a cloud infrastructure, the scalability feature of cloud infrastructures allows us to allocate and release resources according to changing needs. These resource provisioning activities are named runtime control. We propose the Runtime Control method based onSchedule, REactive and PROactive methods (RCSREPRO). Changing needs are mainly caused by the fluctuating workload for majority of the applications running in the cloud. The detailed workload information, for example the request arrival rates at scheduled points in time, is difficult to be known before running the application. Moreover, workload information listed in PSLA is too rough to give a fitted resource provisioning schedule before runtime. Therefore, runtime control decisions are needed to be performed in real time. Since resource provisioning actions usually require several minutes, RCSREPRO performs a proactive runtime control which means that it predicts future needs and assign resources in advance to have them ready when they are needed. Hence, prediction of the workload and workload-resource mapping are two problems involved in proactive runtime control. The workload-resource mapping model, which is initially derived from benchmarks in SLA feasibility study is continuously improved in a feedback way at runtime, increasing the accuracy of the control.To sum up, we contribute with three aspects to the QoS management of application running in the cloud: creation of PSLA, a PaaS level SLA description language; proposal of a benchmark based SLA feasibility study method; proposal of a runtime control method, RCSREPRO, to ensure the SLA when the application is running. The work described in this thesis is motivated and funded by the FSN OpenCloudware project (www.opencloudware.org).

La qualité de service est devenue aujourd'hui une notion incontournable dans le développement des applications logicielles, en particulier dans le cadre des architectures orientées services. Les travaux de cette thèse se focalisent sur la supervision de la qualité de service des applications orientées services, définies sous forme d'orchestrations de services. L'approche de supervision proposée dans ce contexte est générique. Elle repose sur des patrons de flux de contrôle des orchestrations de services pouvant être implémentés en intégralité ou en partie par tout langage d'orchestration de services. D'autre part, elle ne pose aucune restriction, ni sur les attributs qualité à surveiller par le système de supervision, ni sur leurs représentations. Cette approche de supervision se distingue des approches existantes par l'exploitation d'un modèle de préférences orienté utilisateur, permettant de représenter fidèlement la satisfaction de ce dernier. Le degré de satisfaction, issu du modèle de préférences, constitue une information de haut niveau représentant la qualité globale de l'orchestration étudiée. Sur la base de ce degré de satisfaction, de nouvelles stratégies de surveillance sont proposées afin de satisfaire les attentes de l'utilisateur. L'élaboration du modèle de préférences exploite la méthode d'aide à la décision multi-critères MACBETH étendue avec l'opérateur d'agrégation de l'intégrale de Choquet 2-additive. Une illustration de l'approche de supervision a été réalisée sur une orchestration de services, représentant un processus industriel dans le domaine du pilotage d'atelier de production. Les travaux de cette thèse ont été réalisés dans le cadre d'un projet R&D regroupant sept éditeurs de progiciels dans le domaine du MES (Manufacturing Execution System). / Quality of Service (QoS) is an important issue today in the developement of software applications, especially in the context of Service-Oriented Architectures (SOA). The work of this thesis focuses on QoS supervision of service-oriented applications, defined as service orchestrations. The proposed supervision approach is generic. It is based on workflow control-flow patterns, which can be entirety or partillay implemented by any service orchestration language. On the other hand, it does not make any restrictions, neither on the monitored QoS attributes , nor on their representations. This supervision approach is based on a user-oriented preferences model, that represents faithfully the user satisfaction. The satisfaction degree derived from the preferences model is a high-level information representing the overall quality of the orchestration. New monitoring strategies are proposed on the basis of this satisfaction degree in order to satisfy user expectations. The elaboration of the preferences model uses the MACBETH method extended to the 2-additive Choquet integral operator as a multi criteria decision aiding method. An illustration of the approach is carried out on a service orchestration representing a Manufacturing Execution System (MES) process. This work was realized in a R&D project involving seven software vendors in the field of MES.STAR

Virtualization is one of the important enabling technologies for Cloud Computing which facilitates sharing of resources among the virtual machines. However, it incurs performance overheads due to contention of physical devices such as disk and network bandwidth. Various I/O applications having different latency requirements may be executing concurrently on different virtual machines provisioned on a single server in Cloud data-centers. It is pertinent that the performance SLAs of such applications are satisfied through intelligent scheduling and allocation of disk resources. The underlying disk scheduler at the server is unable to distinguish between the application requests being oblivious to the characteristics of these applications. Therefore, all the applica- tions are provided best effort services by default. This may lead to performance degradation for the latency sensitive applications. In this work, we propose a novel disk scheduling framework PriDyn (Dynamic Priority) which provides differentiated services to various I/O applications co-located on a single host based on their latency attributes and desired performance. The framework employs a scheduling algorithm which dynamically computes latency estimates for all concurrent I/O applications for a given system state. Based on these, an appropriate pri- ority assignment for the applications is determined which is taken into consideration by the underlying disk scheduler at the host while scheduling the I/O applications on the physical disk. The proposed scheduling framework is able to successfully satisfy QoS requirements for the concurrent I/O applications within system constraints. This has been verified through ex- tensive experimental analysis. In order to realize the benefits of differentiated services provided by the PriDyn scheduler, proper combination of I/O applications must be ensured for the servers through intelligent meta-scheduling techniques at the Cloud data-center level. For achieving this, in the second part of this work, we extended the PriDyn framework to design a proactive admission control and scheduling framework PCOS (P rescient C loud I/O S cheduler). It aims to maximize to Utilization of disk resources without adversely affecting the performance of the applications scheduled on the systems. By anticipating the performance of the systems running multiple I/O applications, PCOS prevents the scheduling of undesirable workloads on them in order to maintain the necessary balance between resource consolidation and application performance guarantees. The PCOS framework includes the PriDyn scheduler as an important component and utilizes the dynamic disk resource allocation capabilities of PriDyn for meeting its goals. Experimental validations performed on real world I/O traces demonstrate that the proposed framework achieves appreciable enhancements in I/O performance through selection of optimal I/O workload combinations, indicating that this approach is a promising step towards enabling QoS guarantees for Cloud data-centers.

The purpose of quality control within internal auditing functions is to ensure that internal auditing functions add value by providing a quality service. The aim of this research project was to investigate the importance of quality control within internal auditing functions as prescribed by the standards and guidelines of the internal auditing profession. It was also attempted to determine to what extent these standards and guidelines are applied within internal auditing functions in South Africa. The study concluded that quality control is not adequately applied within all internal auditing functions in South Africa. Compliance with the internal auditing standards (implemented on 1 January 2002) should contribute to improve the situation. The internal auditors’ professional body should motivate internal auditing functions to exercise quality control according to the internal auditing standards. This will uplift the image of the internal auditing profession and ensure the future existence of internal auditing functions. / Auditing / M.Comm.

[pt] No cenário atual do setor de telecomunicações, percebe-se uma tendência crescente em direção ao uso de sistemas de comunicação que permitam a criação rápida e de baixo custo de serviços. Na busca por arquiteturas de rede que respondam a essa tendência, vários grupos têm centrado seus esforços em pesquisas na área de redes programáveis. O surgimento da tecnologia de processamento de rede no mercado de equipamentos de telecomunicações abriu ainda maior espaço para pesquisas nessa área. Nesse contexto, é imprescindível que os processos de criação de serviços sejam bem estruturados e, o quanto possível, sistemáticos. Esta tese, inserida em um projeto desenvolvido no Laboratório TeleMídia da PUC-Rio, adota uma abordagem de criação de serviços em que técnicas de Arquitetura de Software e de Desenvolvimento Baseado em Componentes são aplicadas consistentemente e de modo ubíquo, desde especificações de alto nível de serviços até a implementação de software básico em unidades programáveis de processamento de rede. Os objetivos principais são expressar a adaptabilidade de múltiplos aspectos nesses serviços e, simultaneamente, reduzir a sobrecarga cognitiva em projetistas e programadores, decorrente dessa multiplicidade de aspectos. Para isso, foi desenvolvida uma linguagem de especificação baseada em XML, chamada Lindax, que permite descrever arquiteturalmente diversos aspectos de sistemas de comunicação - por meio de um arcabouço sintático único para DSLs - e restrições de adaptação em cada aspecto particular - por meio de estruturas de estilos arquiteturais. Complementando o trabalho, um conjunto de ferramentas de manipulação de descrições arquiteturais em LindaX é definido. Essas ferramentas permitem o refinamento para diferentes linguagens formais ou a síntese de configurações e mecanismos de controle de adaptações para diversas plataformas. / [en] It is increasingly noticeable, in the current telecommunications market, a trend towards using communication systems that allow rapid and cheap deployment of new services. In pursuit of network architectures that keep up with such trend, significant research has been carried out on programmable networks. This field is set to gain further impetus from developments in network processor-based equipment. In this context, it is crucial that service creation processes be well structured and, as far as possible, systematic. This thesis, which is part of an ongoing project at the TeleMídia Laboratory, PUC-Rio, adopts a service creation approach in which techniques from Software Architecture and Component-Based Software Development are uniformly and ubiquitously applied at all levels of a communication system, ranging from high- level service specifications to low-level software implementation running in network processors. The main aim is to express adaptibility in cross-cutting service aspects and, meanwhile, cut down on the cognitive overhead usually imposed upon designers and programmers due to such multiplicity of concerns. For the sake of the aforementioned aim, an XML-based specification language, called LindaX, has been developed. Such language allows various system aspects to be architecturally described - by means of a single syntactic framework for DSLs - as well as adaptable in a constrained way - through style structures. Complementing the work, a toolset for handling LindaX architecture descriptions has been defined, which allows their refinement to different formal languages or their synthesis onto system configurations and adaptation controlling mechanisms for diverse platforms.

Made available in DSpace on 2014-12-17T14:55:52Z (GMT). No. of bitstreams: 1 RenataPB_DISSERT.pdf: 1489254 bytes, checksum: 88fdf1027875fb6b83dbe203da3c24f7 (MD5) Previous issue date: 2011-11-14 / It s notorious the advance of computer networks in recent decades, whether in relation to transmission rates, the number of interconnected devices or the existing applications. In parallel, it s also visible this progress in various sectors of the automation, such as: industrial, commercial and residential. In one of its branches, we find the hospital networks, which can make the use of a range of services, ranging from the simple registration of patients to a surgery by a robot under the supervision of a physician. In the context of both worlds, appear the applications in Telemedicine and Telehealth, which work with the transfer in real time of high resolution images, sound, video and patient data. Then comes a problem, since the computer networks, originally developed for the transfer of less complex data, is now being used by a service that involves high transfer rates and needs requirements for quality of service (QoS) offered by the network . Thus, this work aims to do the analysis and comparison of performance of a network when subjected to this type of application, for two different situations: the first without the use of QoS policies, and the second with the application of such policies, using as scenario for testing, the Metropolitan Health Network of the Federal University of Rio Grande do Norte (UFRN) / ? not?rio o avan?o das redes de computadores nas ?ltimas d?cadas, seja em rela??o ?s taxas de transmiss?o, ao n?mero de dispositivos interconectados ou mesmo ?s aplica??es existentes. Em paralelo, percebemos tamb?m este avan?o nos diversos segmentos da ?rea de automa??o, tais como: industrial, comercial e residencial. Em uma de suas ramifica??es, encontram-se as redes hospitalares, que podem fazer uso de uma gama de servi?os, que v?o desde o simples cadastro de pacientes at? uma cirurgia feita por um rob? sob a supervis?o de um m?dico especialista. No contexto dos dois universos, aparecem as aplica??es em Telemedicina e Telessa?de, que trabalham com a transfer?ncia, em tempo real, de imagens de alta resolu??o, som, v?deo e dados de pacientes. Surge ent?o um problema, visto que as redes de computadores, inicialmente criadas para a transfer?ncia de dados menos complexos, est? sendo agora usada por um servi?o que envolve altas taxas de transfer?ncia e apresenta requisitos em rela??o ? qualidade do servi?o (QoS) oferecido pela rede. Desta forma, este trabalho realiza uma an?lise e compara??o de desempenho de uma rede quando submetida a esse tipo de aplica??o, para duas situa??es distintas: a primeira sem o uso de pol?ticas de QoS, e a segunda com a aplica??o de tais pol?ticas, usando como cen?rio para os testes, a Rede Metropolitana de Sa?de da Universidade Federal do Rio Grande do Norte (UFRN)

Pessoas e organizações ao redor do globo utilizam aplicações multimídia para interação e comunicação. Existe notável crescimento de tráfego característico dessas aplicações, uma vez que há convergência de voz e dados para um modelo único de transporte. As redes de computadores, por suportar tais aplicações cadenciam desafios e oportunidades de negócios que os operadores têm aproveitado. Por outro lado, os usuários experimentam serviços com qualidades cada vez mais refinados, mesmo assim, existem aspectos que devem ser tratados para elevar a qualidade de experiência percebida pelos usuários ao consumir serviços ofertados sobre a internet. Métricas de QoS usualmente são baseadas nos usuários ou na rede, por isso, conceitos como NFV e SDN permitem aprimorar e expandir a perspectiva de oferta de uma camada de abstração para desenvolvimento de soluções flexíveis, que visam lidar com aplicações multimídia ofertadas em nuvem. Não obstante, a construção dessas soluções deve ser calcada em aspectos intrínsecos ao conceito de Internet do Futuro que preconiza soluções virtualizadas, flexíveis, convergentes, escaláveis, orientadas a contexto, seguras e melhor gerenciadas. Este trabalho propõe uma abordagem para mitigar a distância das aplicações com os recursos de rede e computação. Usualmente as aplicações desconhecem características de hardware sobre o qual elas operam; quanto a rede, mesmo com esforços em vários níveis da pilha de protocolos, desconhece especificidades das aplicações em execução. Há também dificuldade de gerenciamento global de recursos, integração de políticas e acordos de serviço entre operadores. O trabalho visa adicionar uma camada de gerenciamento para elevar os níveis de QoS para aplicações multimídia baseadas em NFV. Para realizar isso, é proposto uma entidade que atua no plano de dados e controle, capaz de orquestrar recursos de rede e de computação simultaneamente para aprimorar QoS em aplicações multimídia. A incorporação dessa entidade conquista melhoramento de QoS por meio da oferta de resiliência na comunicação fim-a-fim de entidades consumidoras dessas aplicações, provê um balanceamento de carga adequado a fim de não comprometer parâmetros de QoS como tempo de resposta, provê escalabilidade sob demanda, promove o conceito de inspeção de pacotes para segmentação de políticas de rede orientada à aplicação, finalmente realiza a separação de plano de dados e controle. A construção e experimentação da solução permitiu diminuir tempos de resposta nas aplicações multimídia; a solução reagiu adequadamente frente a cargas de trabalho heterogêneas no sentido de prover confiabilidade para garantia de QoS; também, o conceito de inspeção de pacotes foi capaz de atuar para diminuir a distância que as aplicações possuem da rede e o hardware sobre o qual elas operam. / People and organizations around the globe use multimedia applications for interaction and communication. There is notable traffic growth characteristic of these applications since there is a convergence of voice and data for a single transport model. Computer networks, because they support such applications, meet the challenges and business opportunities that operators have taken advantage of. On the other hand, users use services with increasingly refined qualities, nevertheless, there are aspects that must be addressed to raise the quality of experience for users when consuming services offered over the internet. QoS metrics are usually user-based or network-based, hence concepts such as NFV and SDN allow to improve and expand the perspective of offering an abstraction layer for the development of flexible solutions that deal with multimedia applications offered in the cloud. Nevertheless, the construction of these solutions must be based on intrinsic aspects to the Future Internet concept that advocates virtualized solutions, flexible, convergent, scalable, context-aware, secure and better managed. This dissertation proposes an approach to mitigate the distance of the applications with the resources of compute and network. Usually, the applications are unaware of the hardware characteristics on which they operate, as for the network, even with several efforts at various levels of the protocol stack, the specificities of running applications are unknown. There is also challenges of managing global resources, integrating policies and service agreements between operators. This work aims to add a management layer to raise the levels of QoS for multimedia applications based on NFV. To accomplish this, an entity that acts on the data and control plane is proposed, capable of orchestrating network and computing resources simultaneously to enhance QoS in multimedia applications. The incorporation of this entity achieves QoS improvement through resiliency in the end-to-end communication of the consumer entity of these applications, provides adequate load balancing in order to avoid compromising QoS parameters such as response time, provides on-demand scalability, improves the concept of package inspection for the segmentation of application-oriented network policies, and finally performs the separation of data and control plane. The construction and experimentation of the solution allowed to reduce response times in the multimedia applications. The solution reacted adequately to heterogeneous workloads in order to provide reliability for QoS guarantee. Furthermore, the concept of packet inspection was able to act to decrease the distance that the applications have from the network and the hardware on which they operate. / Dissertação (Mestrado)

Em redes de computadores, para garantir que seja obtido um nível adequado de comunicação fim-a-fim, é importante garantir um roteamento com Qualidade de Serviço (QoS). O problema de roteamento com QoS envolve múltiplos objetivos a serem otimizados ou atendidos simultaneamente. Quando esse roteamento é do tipo multicast, que envolve vários destinatários, a complexidade do problema é ainda maior. Trabalhos anteriores investigam o uso de Algoritmos Evolutivos Multiobjetivos (AEMO) no problema de roteamento multicast com QoS. É sabido que quanto maior é o número de objetivos a serem otimizados, mais complexo se torna o problema multiobjetivo e mais difícil se torna a convergência de AEMOs tradicionais. Por isso, é proposto o uso de um método evolutivo many objective: o AEMMT (Algoritmo Evolutivo Multiobjetivo com Muitas Tabelas). O AEMMT foi especialmente desenvolvido para problemas com um número maior de objetivos e espera-se que ele se comporte mais adequadamente com o aumento do número de objetivos no roteamento multicast com QoS. Com o intuito de forti car a convergência este trabalho propõe um novo many objective baseado nas estratégias do AEMMT, nomeado AEMMD. / In computer networks, to ensure that an adequate level of communication end-to-end is achieved, it is important to ensure a routing with quality of service (QoS). The routing problem with QoS involves multiple objectives to be optimized or serviced simultaneously. When this multicast routing is the kind which involves multiple recipients, the complexity of the problem is even greater. Previous studies investigating the use of evolutionary algorithms Multiobjetivos (AEMO) in multicast routing problem with QoS. It is known that the greater the number of objects to be optimized, the more complex becomes the multiobjective and more difficult problem becomes convergence AEMOs Traditional. Therefore, the use of an evolutionary method many objective is proposed: the AEMMT (Evolutionary Algorithm with Multiobjective Many tables). The AEMMT was specially developed for problems with a large number of objectives and expected it to behave more appropriately with the increasing number of objectives in the multicast routing with QoS. In order to strengthen the convergence this paper proposes a new many objective based on the strategies of AEMMT appointed AEMMD. / Dissertação (Mestrado)