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Publications (3)0 Total impact

  • Open Source Cloud Computing Systems: Practices and Paradigms. 01/2012; 1:222.
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    ABSTRACT: We describe a practical approach applying the UML 2.0 standard MARTE profile to model stochastic interactive application workflows, using the PapyrusUML editor. We use the PaStep, PaCommStep, PaLogicalResource and GaCommHost MARTE stereotypes and find them sufficient for stochastic modelling with the exception of being unable to define non-standard probability distributions. We have investigated both Markovian stochastic models and discrete event simulation models, serializing UML deployment and state machine diagrams to automate model creation. The choice between using a stochastic model (e.g. PRISM Markov models) or discrete event simulation model (e.g. Monte Carlo simulations) depends on the complexity of the model, accuracy required and compute time needed. We find that PRISM models are fast to execute if the complexity is small and produce numerically accurate results. Discrete event simulation models are slower to execute but scale much better and are probably the default solution to a model of unknown complexity.
    eChallenges, 2010; 11/2010
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    ABSTRACT: Cloud computing offers the potential to dramatically reduce the cost of software services through the commoditization of information technology assets and on-demand usage patterns. However, the complexity of determining resource provision policies for applications in such complex environments introduces significant inefficiencies and has driven the emergence of a new class of infrastructure called Platform-as-a-Service (PaaS). In this paper, we present a novel PaaS architecture being developed in the EU IST IRMOS project targeting real-time Quality of Service (QoS) guarantees for online interactive multimedia applications. The architecture considers the full service lifecycle including service engineering, service level agreement design, provisioning and monitoring. QoS parameters at both application and infrastructure levels are given specific attention as the basis for provisioning policies in the context of temporal constraints. The generic applicability of the architecture is being verified and validated through implemented scenarios from three important application sectors (film post-production, virtual augmented reality for engineering design, collaborative e-Learning in virtual worlds).
    2010 Fifth International Conference on Internet and Web Applications and Services; 01/2010