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Focus of this diploma thesis is on Cloud Computing -- a new delivery model of IS/ICT services for companies. Cloud Computing services are IT resources available to users via internet on pay-as-you-use basis. The aim of the thesis is define underlying Cloud Computing concepts and evaluate the current state of Cloud Computing adoption in the Czech Republic. We discuss the framework for definition of Cloud Computing concepts in the theoretical part of the thesis drawing on resources available in the literature. Cloud Computing survey is conducted using an online questionnaire and followsthe principles established in theoretical part. The main contribution of this thesis is creating working definition of Cloud Computing and identifying reasons that affect adoption rate in the Czech Republic.

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Cyber-attack simulation is a suitable method used for assessing the security ofnetwork systems. An attack simulation advances step-wise from a certain systementry-point to explore the attack paths that lead to dierent weaknesses inthe model. Each step is analyzed, and the time to compromise is calculated.Attack simulations are primarily based on attack graphs. The graphs areemployed to model attack steps where nodes can represent assets in the system,and edges can represent the attack steps. To reduce the computational cost associatedwith building an attack graph for each specic system, domain-specicattack languages, or DSL for short, are used.The nal product of this thesis work is azureLang, a probabilistic modelingand simulation language for modeling Microsoft Azure cloud infrastructure.AzureLang is a DSL which denes a generic attack logic for MicrosoftAzure systems. Using azureLang, system administrators can easily instantiatespecic-system scenarios which emulate their Microsoft Azure cloud system infrastructure.After creating the model, attack simulation can be run to assessthe security of the model. / Cyberattacksimulering är en lämplig metod som används för att bedöma säkerhetenhos nätverkssystem. En angrepsimulering går stegvis från ett visst systeminmatningspunkt för att utforska angreppsbanorna som leder till olika svagheter i modellen. Varje steg analyseras och tiden för kompromettera beräknas.Attack-simuleringar baseras huvudsakligen på attackgrafer. Graferna används för att modellera angreppssteg där noder kan representera tillgångar i systemet, och kanterna kan representera attackenstegen. För att minska kostnaden för att skapa attackgrafer för varje specifikt system används domänspecifika språk eller DSL förkortat.Den slutliga produkten av detta examensarbete är azureLang, ett probabilistisk hotmodelleringsoch attacksimuleringsspråk för analys av Microsoft Azure Cloud Infrastructure. AzureLang är en DSL som definierar en generisk attacklogik för Microsoft Azure-system. Med hjälp av azureLang kan systemadministratörer enkelt ordna specifika systemscenarier som efterliknar deras Microsoft Azure cloudsystem infrastruktur. Efter att ha skapat modellen kan attack simu-lering köras för att bedöma modellens säkerhet.

本篇論文將針對線上遊戲產業之雲端運算服務平台之發展進行研究與探討。從線上遊戲產業發展的現況與趨勢中，看到線上遊戲仍是市場的主流，更是付費機制的成熟產品，但也看到新興遊戲如SNS網頁遊戲、App遊戲的衝擊下，線上遊戲已不再是大型遊戲或是只有大型公司才有能力開發製作的產品，而中小型團隊也開始蜂擁加入開發的行列。 在線上遊戲產品開發流程與產業價值鏈的文獻探討中，看到線上遊戲的開發與營運價值單元，且這些價值單元都是非常符合雲端運算的功能與架構，並再透過詳細解析產品開發流程與營運價值鏈的每個環節中去對應雲端運算架構與功能，分析雲端運算對線上遊戲之開發端及消費端所提昇之價值與效益面，以及線上遊戲之雲端運算服務平台的可能功能與服務模式。 線上遊戲因為具備文件、物件資料量龐大、即時運算需求極高、中小型開發團隊須降低軟硬體開發成本需求殷切以及需要共用之伺服器軟硬體環境，還有備援且不允許因維運、修改、除錯等而可能停機或當機之風險產生等特性，使得在這一波雲端運算的潮流與趨勢中，選擇提供線上遊戲開發與營運之雲端運算平台服務，應是一項可預期的發展機會。 本研究最後透過一家已推出線上遊戲雲端運算服務平台的個案研究，再呼應前面線上遊戲與雲端運算功能與架構的關聯框架及分析，最後提出對個案公司應以大量即時運算為核心能力，提供跨業服務、以核心技術發展技轉與合作營運模式、結合HTML5或Yahoo的YUI等技術，全力搶攻新興連線遊戲市場、研發雲端Server端引擎產品等建議外，也對線上遊戲之雲端運算服務平台提出可發展SaaS、PaaS、IaaS等各別專業及可具備彈性且可發展成機動組合的混合型雲端服務模式之結論與建議等。 / This report is the research and investigation of the cloud computing platform development in online game industry. We find that online game is still the mainstream as well as a developed product under the paid mechanisms through the condition and trend of online game industry. However, because of the impact of SNS website game and App game, the online game no longer just a hug online game or develop by big companies, instead the medium and small groups can develop the online game as well now. We find out that there are some unites in the literature investigated the development process and industrial value chain of online fit in with the function of cloud computing and its framework. In addition, we will do the detailed analysis of production developing process and operation value to correspond to the function and framework of cloud computing, analyze the value and benefit the cloud computer can do to improve the beginning and consumption-side of online game and its possible function and service mode for online game. The online game needs huge quantity of data in document and object, so the need of instant cloud computing is high. For that reason, when develop the software and hardware, the medium and small groups need to reduce the cost. Moreover, they need the server that can use in both new software and hardware, the backup, un-interruptible power supply and the feature of operating normally while doing the maintenance, modification, debug, etc. So, in the trend of current cloud computing, one of the predictable development opportunity is have the cloud computing platform service that can help to develop and operate online game. In the end, the study will take the case study of cloud computing platform that have released online game as example, correspond to the relevant framework and analysis from the previous online game and the function and framework of cloud computing and finally give the suggests and conclusion to the case company, which is taking great amount of instant cloud computing as core ability, provide cross-field services, use core technology development transformation and cooperation service mode, The use of HTML5 or Yahoo's YUI technology put in all effort to earn the new market of online game and research and develop the cloud computer server engine. Other than that, we also bring up the individual professional service that can develop in the cloud computing platform of online game such as SaaS, PaaS, IaaS and the suggestions and conclusions relate to the flexible and assembling-based complex cloud service.

Virtualisation is one of the underlying technologies that led to the success of cloud computing platforms (CCPs). The technology, along with other features such as multitenancy allows delivering of computing resources in the form of service through efficient sharing of physical resources. As these resources are provided through virtualisation, a robust agreement is outlined for both the quantity and quality-of-service (QoS) in a service level agreement (SLA) documents. QoS is one of the essential components of SLA, where performance is one of its primary aspects. As the technology is progressively maturing and receiving massive acceptance, researchers from industry and academia continue to carry out novel theoretical and practical studies of various essential aspects of CCPs with significant levels of success. This thesis starts with the assessment of the current level of knowledge in the literature of cloud computing in general and CCPs in particular. In this context, a substantive literature review was carried out focusing on performance modelling, testing, analysis and evaluation of Infrastructure as a Service (IaaS), methodologies. To this end, a systematic mapping study (SMSs) of the literature was conducted. SMS guided the choice and direction of this research. The SMS was followed by the development of a novel open queueing network model (QNM) at equilibrium for the performance modelling and analysis of an OpenStack IaaS CCP. Moreover, it was assumed that an external arrival pattern is Poisson while the queueing stations provided exponentially distributed service times. Based on Jackson’s theorem, the model was exactly decomposed into individual M/M/c (c ≥ 1) stations. Each of these queueing stations was analysed in isolation, and closed-form expressions for key performance metrics, such as mean response time, throughput, server (resource) utilisation as well as bottleneck device were determined. Moreover, the research was extended with a proposed open QNM with a bursty external arrival pattern represented by a Compound Poisson Process (CPP) with geometrically distributed batches, or equivalently, variable Generalised Exponential (GE) interarrival and service times. Each queueing station had c (c ≥ 1) GE-type servers. Based on a generic maximum entropy (ME) product form approximation, the proposed open GE-type QNM was decomposed into individual GE/GE/c queueing stations with GE-type interarrival and service times. The evaluation of the performance metrics and bottleneck analysis of the QNM were determined, which provided vital insights for the capacity planning of existing CCP architectures as well as the design and development of new ones. The results also revealed, due to a significant impact on the burstiness of interarrival and service time processes, resulted in worst-case performance bounds scenarios, as appropriate. Finally, an investigation was carried out into modelling and analysis of performance and security trade-offs for a CCP architecture, based on a proposed generalised stochastic Petri net (GSPN) model with security-detection control model (SDCM). In this context, ‘optimal’ combined performance and security metrics were defined with both M-type or GE-type arrival and service times and the impact of security incidents on performance was assessed. Typical numerical experiments on the GSPN model were conducted and implemented using the Möbius package, and an ‘optimal’ trade-offs were determined between performance and security, which are crucial in the SLA of the cloud computing services. / Petroleum technology development fund (PTDF) of the government of Nigeria Usmanu Danfodiyo University, Sokoto

La technologie actuelle permet aux scientifiques de divers domaines d'obtenir des données de plus en plus précises et volumineuses, Afin de résoudre ces problèmes associés à l'obtention de ces données, les architectures de calcul évoluent, en fournissant toujours plus de ressources, notamment grâce à des machines plus puissantes et à leur mutualisation. Dans cette thèse, nous proposons d’étudier dans un premier temps le placement des tâches d'applications itératives asynchrones dans des environnements hétérogènes et volatils. Notre solution nous permet également de s'affranchir de l(hétérogénéité des machines hôtes tout en offrent une implantation facilitée de politiques de tolérance aux pannes, les expérimentations que nous avons menées sont encourageantes et montrent qu'il existe un réel potentiel quand à l'utilisation d'une telle plateforme pour l'exécution d'applications scientifiques. / The current technology allows scientists of several domains to obtain more precise and large data. In the same time, computing architectures evolve too, by providing even more computing resources, with more powerful machines and the pooling of them. In this thesis, in a first time we propose to study the problem of the mapping of asynchronous iterative applications tasks into heterogeneous and volatile environments. Our solution allows also to overcome the heterogeneity of host machines while offering an easier implementation of policies for fault tolerance. The experiments we have conducted are encouraging ad show that there is real potential for the use of such a platform for running scientific applications.