Context. With the evolvement of cloud computing in recent years many companies have stated providing various services using it. Desktop as a Service, DaaS is one of services in the cloud computing in which the backend of Virtual Desktop Infrastructure, VDI is hosted by a cloud service provider. Although in SaaS, Software as a Service Web applications are used, all kinds of applications can be used in DaaS. There are many companies which provide VDI for private cloud and they are VMware Horizon, XenDesktops by Citrix, OpenStack VDI solution and etc. Objectives. In this thesis two VDI solutions are analyzed based on the virtual desktop launch time and the performance of the desktop in various test cases. The VDI solutions considered are VMware Horizon view and OpenStack VDI. Methods. The method for this research consists of two stages. The first stage was a qualitative analysis in which literature study and a survey was conducted. In the next stage, experiment was setup where different performance metrics were calculated when the virtual desktop was put under several test cases. Results. Results collected include the virtual desktops launch time in two scenarios and several performance metrics such as CPU usage, memory usage, average IO size, average latency, throughput, IOPS and queue length at the processor. Conclusions. Performance of Virtual desktop running on OpenStack VDI was better in most of the test cases. In the test scenario where disk was put under stress OpenStack VDI solution performance was better than VMware Horizon View. Even considering the launch time for virtual desktops, OpenStack VDI performed better compared to VMware Horizon View.

Avec l'émergence du mouvement Open Data, des centaines de milliers de sources de données provenant de divers domaines (e.g., santé, gouvernementale, statistique, etc.) sont maintenant disponibles sur Internet. Ces sources de données sont accessibles et interrogées via des services cloud DaaS, et cela afin de bénéficier de la flexibilité, l'interopérabilité et la scalabilité que les paradigmes SOA et Cloud Computing peuvent apporter à l'intégration des données. Dans ce contexte, les requêtes sont résolues par la composition de plusieurs services DaaS. Définir la sémantique des services cloud DaaS est la première étape vers l'automatisation de leur composition. Une approche intéressante pour définir la sémantique des services DaaS est de les décrire comme étant des vues sémantiques à travers une ontologie de domaine. Cependant, la définition de ces vues sémantiques ne peut pas être toujours faite avec certitude, surtout lorsque les données retournées par un service sont trop complexes. Dans cette thèse, nous proposons une approche probabiliste pour représenter les services DaaS à sémantique incertaine. Dans notre approche, un service DaaS dont la sémantique est incertaine est décrit par plusieurs vues sémantiques possibles, chacune avec une probabilité. Les services ainsi que leurs vues sémantiques possibles sont représentées dans un registre de services probabiliste (PSR). Selon les dépendances qui existent entre les services, les corrélations dans PSR peuvent être représentées par deux modèles différents : le modèle Bloc-indépendant-disjoint (BID), et le modèle à base des réseaux bayésiens. En se basant sur nos modèles probabilistes, nous étudions le problème de l'interprétation d'une composition existante impliquant des services à sémantique incertaine. Nous étudions aussi le problème de la réécriture de requêtes à travers les services DaaS incertains, et nous proposons des algorithmes efficaces permettant de calculer les différentes compositions possibles ainsi que leurs probabilités. Nous menons une série d'expérimentation pour évaluer la performance de nos différents algorithmes de composition. Les résultats obtenus montrent l'efficacité et la scalabilité de nos solutions proposées / With the emergence of the Open Data movement, hundreds of thousands of datasets from various concerns (e.g., healthcare, governmental, statistic, etc.) are now freely available on Internet. A good portion of these datasets are accessed and queried through Cloud DaaS services to benefit from the flexibility, the interoperability and the scalability that the SOA and Cloud Computing paradigms bring to data integration. In this context, user’s queries often require the composition of multiple Cloud DaaS services to be answered. Defining the semantics of DaaS services is the first step towards automating their composition. An interesting approach to define the semantics of DaaS services is by describing them as semantic views over a domain ontology. However, defining such semantic views cannot always be done with certainty, especially when the service’s returned data are too complex. In this dissertation, we propose a probabilistic approach to model the semantic uncertainty of data services. In our approach, a DaaS service with an uncertain semantics is described by several possible semantic views, each one is associated with a probability. Services along with their possible semantic views are represented in probabilistic service registry (PSR).According to the services dependencies, the correlations in PSR can be represented by two different models :Block-Independent-Disjoint model (noted BID), and directed probabilistic graphical model (Bayesian network). Based on our modeling, we study the problem of interpreting an existing composition involving services with uncertain semantics. We also study the problem of compositing uncertain DaaS services to answer a user query, and propose efficient methods to compute the different possible compositions and their probabilities. We conduct a series of experiments to evaluate the performance of our composition algorithms. The obtained results show the efficiency and the scalability of our proposed solutions

Les infrastructures de calcul scientifique sont en constante évolution, et l’émergence de nouvelles technologies nécessite l’évolution des mécanismes d’ordonnancement qui leur sont associé. Durant la dernière décennie, l’apparition du modèle Cloud a suscité de nombreux espoirs, mais l’idée d’un déploiement et d’une gestion entièrement automatique des plates-formes de calcul est jusque la resté un voeu pieu. Les travaux entrepris dans le cadre de ce doctorat visent a concevoir un moteur de gestion de workflow qui intègre les logiques d’ordonnancement ainsi que le déploiement automatique d’une infrastructure Cloud. Plus particulièrement, nous nous intéressons aux plates-formes Clouds disposant de système de gestion de données de type DaaS (Data as a Service). L’objectif est d’automatiser l’exécution de workflows arbitrairement complexe, soumis de manière indépendante par de nombreux utilisateurs, sur une plate-forme Cloud entièrement élastique. Ces travaux proposent une infrastructure globale, et décrivent en détail les différents composants nécessaires à la réalisation de cette infrastructure :• Un mécanisme de clustering des tâches qui prend en compte les spécificités des communications via un DaaS ;• Un moteur décentralisé permettant l’exécution des workflows découpés en clusters de tâches ;• Un système permettant l’analyse des besoins et le déploiement automatique. Ces différents composants ont fait l’objet d’un simulateur qui a permis de tester leur comportement sur des workflows synthétiques ainsi que sur des workflows scientifiques réels issues du LBMC (Laboratoire de Biologie et Modélisation de la Cellule). Ils ont ensuite été implémentés dans l’intergiciel Diet. Les travaux théoriques décrivant la conception des composants, et les résultats de simulations qui les valident, ont été publié dans des workshops et conférences de portée internationale. / The constant development of scientific and industrial computation infrastructures requires the concurrent development of scheduling and deployment mechanisms to manage such infrastructures. Throughout the last decade, the emergence of the Cloud paradigm raised many hopes, but achieving full platformautonomicity is still an ongoing challenge. Work undertaken during this PhD aimed at building a workflow engine that integrated the logic needed to manage workflow execution and Cloud deployment on its own. More precisely, we focus on Cloud solutions with a dedicated Data as a Service (DaaS) data management component. Our objective was to automate the execution of workflows submitted by many users on elastic Cloud resources.This contribution proposes a modular middleware infrastructure and details the implementation of the underlying modules:• A workflow clustering algorithm that optimises data locality in the context of DaaS-centeredcommunications;• A dynamic scheduler that executes clustered workflows on Cloud resources;• A deployment manager that handles the allocation and deallocation of Cloud resources accordingto the workload characteristics and users’ requirements. All these modules have been implemented in a simulator to analyse their behaviour and measure their effectiveness when running both synthetic and real scientific workflows. We also implemented these modules in the Diet middleware to give it new features and prove the versatility of this approach.Simulation running the WASABI workflow (waves analysis based inference, a framework for the reconstruction of gene regulatory networks) showed that our approach can decrease the deployment cost byup to 44% while meeting the required deadlines.

In these days the term virtualization is almost everywhere, especially in relation with server virtualization. One of the main goals is to describe the part of virtualization which is today not so known although it could have the same meaning for companies as the server virtualization had a few years ago. It is a desktop virtualization and this work includes not just a wide description of this but also related technologies such as data storage virtualization, application virtualization and cloud computing. Another goal is to hold desktop virtualization and find its benefits by placing into the area of small and medium businesses. Thesis is not focused only on the positives of using this technology but also on overall aspects of its use including related risks. Entire part of this thesis is business plan of the company that currently offers virtualization as a complex service for small and medium enterprises. Essential is not just a complete description of the fast growing area, but also concept the practical filling by the plan, which is in the acceptable form for potential investor.

Yes / In order to grow the food the world needs, there is a pressing need to gain a more detailed understanding of how innovative solutions can be incorporated into the agricultural supply chains, particularly within production, for environmentally, economically, ethically and socially viable food production. Despite a number of innovative solutions available, many challenges in agricultural supply are still prevalent, with researchers to date largely focusing on these challenges in isolation, as opposed to exploring the relationships held between these challenges. Thus, supported by Circular Economy, Agriculture, Industry 4.0 literature and expert opinions, agricultural supply chain challenges are modelled and analysed using ISM methodology to help uncover 12 agricultural challenges which ultimately impede goods moving within the supply chain. Findings discovered that the Unproductive Workers and Pesticide Hazards are the key drivers of agricultural challenges. The ISM Hierarchical model elucidates research propositions and a parsimonious model for future research.

Made available in DSpace on 2016-06-02T19:06:15Z (GMT). No. of bitstreams: 1 6233.pdf: 2978713 bytes, checksum: bacd196ac56a6f20318345d645546b83 (MD5) Previous issue date: 2014-02-25 / A server cluster connected to the Internet can support virtual desktops in a virtual computing environment. Each user can have his/her own virtual desktop, accessed through the Internet by means of devices such as laptop, PC, notebook, tablet or smartphone. The benefits of desktop virtualization include the possibility of improving utilization of computational resources such as processor, memory, disk and network; a more efficient management; centralized backup, and remote accessibility independently on the user location. Education institutions have traditionally used local desktops for use of faculty, administrative and technical staffs, as well as for their students. Managing these desktops requires a technical staff to take care of installation, configuration, updating and maintaining in a personalized manner, according to each user profile. In this manner, administration is costly and inefficient. Several companies increasingly adopted virtual desktops delivered by an infrastructure of centralized servers, while education institutions are late in this process. The diversity of applications used by different areas of teaching create demand for studies to better understand the performance of virtual desktop infrastructure. The purpose of this study is to evaluate virtual desktop infrastructure from the perspective of user quality of experience. To accomplish this, a virtual desktop infrastructure have been deployed at UFSCAR, and a set of experiments were carried out at our labs employing five different applications. To evaluate the influence of the networking quality of service on the user experience, we produced 5 scenarios with different communication latencies. Finally, we also executed experiments to evaluate the demand for computational resources (e.g., processor, memory, I/O, and network) as more virtual desktops are spawned. This experiment can provide important information for future capacity planning. / Um conjunto de servidores conectados à Internet pode prover desktops virtuais em um ambiente virtual de computação. Cada usuário pode ter seu próprio desktop virtual, acessando através da Internet por meio de dispositivos como um computador comum ou dispositivos moveis, como um notebook, tablet ou celular. Dentre os benefícios da virtualização de desktops, incluem-se a melhoria na utilização dos recursos de computacionais como processador, memória, disco e rede, a redução de custos para a administração dos recurso (que passa a atuar de forma centralizada e mais eficiente), backup centralizado e possibilidade de acesso remoto, onde quer que o usuário esteja. Muitas empresas já vem adotando o uso de desktops virtuais no ambiente de trabalho dos seus funcionários e colaboradores. Entre¬tanto, as instituições de ensino tradicionalmente utilizam desktops locais, tanto para uso do corpo docente, corpo administrativo e técnico, como também para os seus alunos. Como o tema e bem pouco explorado no ambiente de universidades e instituições de ensino superior, o presente trabalho tem como objetivo principal responder algumas questões sobre a utilização de desktops virtuais. O que se pode esperar em termos da qualidade de experiência dos usuários de desktops virtuais em função de sua execução remota? Quais aplicações típicas apresentam maior ou menor degradação em termos de qualidade de experiência a medida que alguns parâmetros da rede (como por exemplo a latência) se degradam? Qual e o consumo de recursos (processador, memória, E/S e rede) para a execução de desktops virtuais? Como principais contribuições, este trabalho apresenta uma avaliação experimental de uma infraestrutura de desktops virtuais implementada na Secretaria de Informática da UFSCar. Foram realizados experimentos para avaliar a qualidade de experiência do usuário com um conjunto de cinco aplicações típicas de um laboratório de ensino da universidade. Foram testados seis níveis de qualidade de serviço da rede para medir o seu impacto na qualidade de experiência dos usuários. Também foram feitos testes variando-se a quantidade de desktops virtuais executando simultaneamente para verificar o consumo de recursos, que servirá de base para um futuro planejamento de capacidade.

Hepatitis C virus (HCV) infection globally affects 130-150 million people. It causes both acute and chronic infections. Due to the severe side effects and low success rates of interferon based treatments, which formed the standard treatment for HCV, the treatment paradigm shifted to direct acting antivirals (DAAs). DAAs have revolutionized the treatment of hepatitis C virus infection. Clinical trials with combinations of DAAs have recorded >90% response with shorter treatment durations and fewer side effects than earlier treatments involving IFN. Outside the controlled setting of a clinical trial, however, response rates with DAA combinations are much lower (<70%). DAAs can fail if HCV accumulates mutations that confer drug resistance. Interestingly, the pre-existence of mutant frequency in the virus appears not to influence treatment outcome. A better predictor for DAA treatment outcome is yet to be unravelled. Surprisingly, individuals who respond poorly to IFN appear to be more likely to fail DAA treatment. IFN is a generic antiviral that improves immune responses and is expected not to have any bearing on DAA treatment outcomes. Why individuals with poor IFN sensitivity fail DAA treatment remains a mystery. In a recent study of the IFN signalling network, HCV has been shown to compromise IFN activity. It induces bistability in the network leading to distinct phenotypic responses of cells to IFN exposure. In particular, individuals who respond poorly to IFN tend to have a higher percentage of cells that are refractory to IFN; these cells allow viral persistence despite IFN exposure. We hypothesized here that in such individuals, greater ongoing replication would allow increased development of resistance and thus lead to the failure of DAAs. We constructed a model of viral dynamics that accounts for the distinct phenotypic responses of cells to IFN, viral replication and mutation, and the development of resistance to DAAs. Our model predicted that although the relative prevalence of pre- existing mutants is unaffected by IFN sensitivity, in agreement with observations, the growth of drug resistant mutants is accelerated in individuals with poor IFN sensitivity. Based on a distribution of IFN sensitivity across individuals, our model accurately described clinical observations of the response rates to different current treatment protocols. With this model, we predict that the common strategy of increasing the genetic barrier by adding more drugs to the combination was not necessary to avert the development of drug resistance. Instead, an optimised increase in DAA dosage alone or DAA+PR or PR dosage depending on the patient’s IFN sensitivity could help achieve success.

Dans cette thèse, nous intéressons à l'automatisation de la composition de service Web d'accès aux données (i.e. DaaS Data-gs-g-S..ervice Web services) pour les besoins de partage de données dans les environnements distribués. La composition de service Web permet de répondre aux besoins d'un utilisateur ne pouvant être satisfaits par un seul Web service, alors qu'une intégration de plusieurs le permettrait. La motivation principale de notre travail est que les méthodes de composition, telles qu'elles sont appliquées aux services Web traditionnels (i.e. AaaS Application-as-a-Service Web services), ne permettent pas de prendre en compte la relation sémantique entre les entrées/sorties d'un service Web d'accès aux données, et en conséquence, elles ne sont pas adaptées pour composer les services Web d'accès aux données. Dans ce travail de thèse, nous proposons d'exploiter les principes de base des systèmes d'intégration des données pour composer les services Web d'accès aux données. Plus précisément, nous modélisons les services Web d'accès aux données comme des vues sur des ontologies de domaine. Cela permet de représenter la sémantique d'un service d'une manière déclarative en se basant sur des concepts et des relations dont les sémantiques sont formellement définies dans l'ontologie de domaine. Ensuite, nous utilisons les techniques de réécriture des requêtes pour sélectionner et composer automatiquement les services pour répondre aux requêtes des utilisateurs. Comme les services Web d'accès aux données peuvent être utilisés pour accéder à des données sensibles et privées, nous proposons également un mécanisme basé sur la modification des requêtes pour préserver la confidentialité des données. Ce mécanisme modifie les requêtes en se basant sur des politiques de confidentialité avant leur résolution par 1' algorithme de composition, et il prend en considération les préférences des utilisateurs quant à la divulgation de leurs données privées. Le principal domaine d'application de notre approche est le domaine d'e-santé, où les services Web d'accès aux données sont utilisés pour partager les dossiers médicaux des patients. / In this dissertation, we propose a novel approach for the automatic composition of DaaS Web services (DaaS Data-gs-g-S.ervice Web services). Automatic DaaS Web service composition requires dealing with three major research thrusts: (i) describing the semantics of DaaS Web services, (ii) selecting and combining relevant DaaS Web services, and (iii) generating composite service descriptions (i.e. the compositions' plans). We first propose to model DaaS Web services as RDF views over domain ontologies. An RDF view allows capturing the semantics of the associated DaaS Web service in a "declarative" way based on concepts and relationships whose semantics are formally defined in domain ontologies. The service description files (i.e. WSDL files) are annotated with the defined RDF views using the extensibility feature of the WSDL standard. We then propose to use query rewriting techniques for selecting and composing DaaS Web services. Specifically, we devised an efficient RDF-oriented query rewriting algorithm that selects relevant services based ontheir defined RDF views and combines them to ans~wer a posed query. It also generates an execution plan for the obtained composition/s. Our algorithm takes into account the RDFS semantic constraints (i.e. "subClassOf", "subPropertyOf", "Domain" and "Range") and is able to address both specifie and parameterized queries. Since DaaS Web services may be used to access sensitive and private data; we also extended our DaaS service composition approach to handle data privacy concems. Posed queries are modified to accommodate pertaining privacy conditions from data privacy policies before their resolution by the core composition algorithm. Our proposed privacy preservation model takes user' s privacy preferences into account.