Quality of service modeling for green scheduling in Clouds

International audienceBest known Cloud providers propose services under constraints of Service Level Agreement (SLA) definitions.The SLAs are composed of different Quality of Service (QoS) rules promised by the provider. Thus, the QoSin Clouds becomes more and more important. Precise definitions and metrics have to be explained. Thisarticle proposes an overview of Cloud QoS parameters as well as their classification, but also it defines usablemetrics to evaluate QoS parameters. Moreover, the defined QoS metrics are measurable and reusable in anyscheduling approach for Clouds. Energy consumption is an inherent objective in Cloud Computing, thus, it isalso considered. For evaluation purposes, two uncommon QoS parameters: Dynamism and Robustness are takeninto account in different Cloud virtual machines scheduling approaches. Validation is done through comparisonof common scheduling algorithms, including a genetic algorithm (GA), in terms of QoS parameters evolutionin time. Simulation results have shown that including various QoS parameters allows a deeper schedulingalgorithms analysi

Authentication and Identity Management for the EPOS Project

The increase in the number of online services emphasizes the value of authentication and identity management that we, even without realizing, depend on. In EPOS this authentication and identity management are also crucial, by dealing and being responsible for large amounts of heterogeneous data in multiple formats and from various providers, that can be public or private. Controlling and identify the access to this data is the key. For this purpose, it is necessary to create a system capable of authenticating, authorizing, and account the usage of these services. While services in a development phase can have authentication and authorization modules directly implemented in them, this is not an option for legacy services that cannot be modified. This thesis regards the issue of providing secure and interoperable authentication and authorization framework, associated with correct identity management and an accounting module, stating the difficulties faced and how to be addressed. These issues are approached by implementing the proposed methods in one of the GNSS Data and Products TCS services, that will serve as a study case. While authentication mechanisms have improved constantly over the years, with the addition of multiple authentication factors, there is still not a clear and defined way of how authentication should be done. New security threats are always showing up, and authentication systems need to adapt and improve while maintaining a balance between security and usability. Our goal is, therefore, to propose a system that can provide a good user experience allied to security, which can be used in the TCS services or other web services facing similar problems.A importância da autenticação e gestão de identidades, de que dependemos inconscientemente, aumenta com o crescimento do número de serviços online ao nosso dispor. No EPOS, devido à disponibilização e gestão de dados heterogéneos de várias entidades, que podem ser públicas ou privadas, a existência de um sistema de autenticação e gestão de identidades é também crucial, em que o controlo e identificação do acesso a estes dados é a chave. Numa fase de desenvolvimento dos serviços, estes módulos de autenticação e autorização podem ser diretamente implementados e é possível existir uma adaptação do software aos mesmos. No entanto, há serviços já existentes, cujas alterações implicam mudanças de grande escala e uma reformulação de todo o sistema, e como tal não é exequível fazer alterações diretas aos mesmos. Esta dissertação aborda o desenvolvimento de um sistema de autenticação e autorização seguro e interoperável, associado a uma correta gestão de identidades e um módulo de controlo, identificando os problemas encontrados e propondo soluções para os mesmos. Este desenvolvimento é aplicado num dos serviços do TCS GNSS Data and Products e servirá como caso de estudo. Embora os mecanismos de autenticação tenham melhorado continuamente ao longo dos anos, com a adição de vários fatores de autenticação, ainda não existe um método único e claro de como a autenticação deve ser feita. Novas ameaças estão sempre a surgir e os sistemas atuais precisam de se adaptar e melhorar, mantendo um equilíbrio entre segurança e usabilidade. O nosso objetivo é propor um sistema que possa aliar a segurança a uma boa experiência para o utilizador, e que possa ser utilizado não só nos serviços do TCS, mas também em outros serviços web que enfrentem problemas semelhantes

Ordonnancement sous contraintes de qualité de service dans les clouds

In recent years, new issues have arisen in environmental considerations, increasingly pointed out in our society. In the field of Information Technology, data centers currently consume about 1.5% of world electricity. This increasing is due to changes in many areas, especially in Cloud Computing. Besides this environmental aspect, the management of energy consumption has become an important field of Quality of Service (QoS), in the responsibility of Cloud providers. These providers propose a QoS contract called SLA (Service Level Agreement), which specify the level of QoS given to users. The level of QoS offered directly influences the quality of the users' utilization, but also the overall energy consumption and performance of computing resources, which strongly affect profits of the Cloud providers. Cloud computing is intrinsically linked to the virtualization of computing resources. A model of hardware and software architecture is proposed in order to define the characteristics of the environment considered. Then, a detailed modeling of QoS parameters in terms of performance, dependability, security and cost is proposed. Therefore, QoS metrics, associated to these parameters are defined in order to extend the possibilities for evaluating the SLA. These models represent the first contribution of this thesis. Then, it is necessary to illustrate how the use and interpretation of several QoS metrics open the possibility of a more complex and precise analysis of algorithms' insight. This multi-criteria approach, that provides useful informations about the system's status can be analyzed to manage the QoS parameters' level. Thus, four antagonists metrics, including energy consumption, are selected and used together in several scheduling algorithms which allow to show their relevance, the enrichment given to these algorithms, and how a Cloud provider can take advantage of the results of this kind of multi-objective optimization. The second contribution presents a genetic algorithm (GA) and two greedy algorithms. The analysis of the genetic algorithm behavior allows to show different interests of a multi-criteria optimization applied to QoS metrics, usually ignored in studies dedicated to Cloud Computing. The third contribution of this thesis proposes a study of the impact of the use of QoS metrics in virtual machines scheduling. The simulator CloudSim has been used and expanded to improve its energy-aware tools. The DVFS (Dynamic Voltage & Frequency Scaling), providing a highly accurate dynamic management of CPU frequencies, the virtual machines reconfiguration, and the dynamic management of events have been included. The simulations involve all of these energy tools and placement algorithms, and evaluate each selected QoS metrics. These simulations allow to see the evolution in time of these metrics, depending on the algorithms used and the behavior of the GA in different optimizations configurations. This allows to analyze from different angles the behavior of greedy algorithms, the impact of optimizations GA, and the influence of these metrics one against the others.Ces dernières années, de nouvelles problématiques sont nées au vu des considérations écologiques de plus en plus présentes dans notre société. Dans le domaine de la technologie de l'Information, les centres de calcul consomment actuellement environ 1.5% de l'électricité mondiale. Cela ne cesse d’augmenter en raison de l'évolution de nombreux domaines et particulièrement du Cloud Computing. Outre cet aspect environnemental, le contrôle de la consommation d’énergie fait désormais partie intégrante des paramètres de Qualité de Service (QoS) incombant aux fournisseurs de services de Cloud Computing. En effet, ces fournisseurs de services à la demande proposent à leurs utilisateurs un contrat de QoS, appelé SLA (Service Level Agreement), qui définit de manière précise la qualité de service qu’ils s’engagent à respecter. Le niveau de QoS proposé influence directement la qualité d’utilisation des services par les utilisateurs, mais aussi la consommation et le rendement général de l’ensemble des ressources de calcul utilisées, impactant fortement les bénéfices des fournisseurs de services.Le Cloud Computing étant intrinsèquement lié à la virtualisation des ressources de calcul, une élaboration de modèles d’architecture matérielle et logicielle est proposée afin de définir les caractéristiques de l’environnement considéré. Ensuite, une modélisation détaillée de paramètres de QoS en termes de performance, de sûreté de fonctionnement, de sécurité des données et de coûts est proposée. Des métriques associées à ces paramètres sont définies afin d’étendre les possibilités d'évaluation des SLA. Ces modélisations constituent la première contribution de cette thèse.Il convient alors de démontrer comment l’utilisation et l’interprétation de plusieurs métriques de QoS ouvrent la possibilité d'une analyse plus complexe et plus fine de la perspicacité des algorithmes de placement. Cette approche multi-critères leur apporte des informations importantes sur l’état de leur système qu’ils peuvent analyser afin de gérer le niveau de chaque paramètre de QoS. Ainsi, quatre métriques antagonistes, incluant la consommation énergétique, ont été sélectionnées et utilisées conjointement dans plusieurs algorithmes de placement de manière à montrer leur pertinence, l’enrichissement qu’elles apportent à ces algorithmes, et comment un fournisseur de service peut tirer profit des résultats d’une optimisation multi-objectifs. Cette seconde contribution présente un algorithme génétique (GA) ainsi que deux algorithmes gloutons. L’analyse du comportement de l'algorithme génétique a permis de démontrer différents intérêts d’une optimisation multi-critères appliquée à des métriques de QoS habituellement ignorées dans les études dédiées au Cloud Computing.La troisième contribution de cette thèse propose une étude de l’impact de l'utilisation des métriques de QoS sur l’ordonnancement de machines virtuelles au cours du temps. Pour cela, le simulateur CloudSim a été exploité et étendu afin d'améliorer ses fonctionnalités de gestion de consommation énergétique. Tout d’abord par l’ajout du DVFS (Dynamic Voltage & Frequency Scaling) apportant une gestion dynamique très précise des fréquences de fonctionnement CPU, puis la possibilité de reconfiguration de machines virtuelles et enfin par la gestion dynamique des évènements. Les simulations effectuées mettent en jeu l'ensemble de ces outils énergétiques ainsi que les algorithmes de placement et évaluent chacune des métriques de QoS sélectionnées. Ces simulations donnent une vision temporelle de l’évolution de celles-ci, en fonction des algorithmes utilisés et de plusieurs configurations d’optimisation du GA. Cela permet d'analyser sous différents angles le comportement des algorithmes gloutons, l'impact des optimisations du GA, et l'influence des métriques les unes par rapport aux autres.Une collaboration a pu être établie avec le laboratoire CLOUDS Laborartory de Melbourne, dirigé par Prof. Rajkumar Buyya