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Xiao Liu PhD Thesis.pdf - Faculty of Information and Communication ...

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Chapter 1<br />

Introduction<br />

This thesis proposes a novel probabilistic temporal framework to address the<br />

limitations <strong>of</strong> conventional temporal research <strong>and</strong> the new challenges for lifecycle<br />

support <strong>of</strong> time-constrained e-science applications in cloud workflow systems. The<br />

novel research reported in this thesis is concerned with the investigation <strong>of</strong> how to<br />

deliver high temporal QoS (Quality <strong>of</strong> Service) from the perspective <strong>of</strong> cost<br />

effectiveness, especially at workflow runtime. A set <strong>of</strong> new concepts, innovative<br />

strategies <strong>and</strong> algorithms are designed <strong>and</strong> developed to support temporal QoS over<br />

the whole lifecycles <strong>of</strong> scientific cloud workflow applications. Case study,<br />

comparisons, quantitative evaluations <strong>and</strong>/or theoretical pro<strong>of</strong>s are conducted for<br />

each component <strong>of</strong> the temporal framework. This would demonstrate that with our<br />

new concepts, innovative strategies <strong>and</strong> algorithms, we can significantly improve the<br />

overall temporal QoS in scientific cloud workflow systems.<br />

This chapter introduces the background, motivations <strong>and</strong> key issues <strong>of</strong> this<br />

research. It is organised as follows. Section 1.1 gives a brief introduction to temporal<br />

QoS in cloud workflow systems. Section 1.2 presents a motivating example from a<br />

scientific application area. Section 1.3 outlines the key issues <strong>of</strong> this research.<br />

Finally, Section 1.4 presents an overview for the remainder <strong>of</strong> this thesis.<br />

1.1 Temporal QoS in Scientific Cloud Workflow Systems<br />

Cloud computing is a latest market-oriented computing paradigm [11, 37]. It refers<br />

to a variety <strong>of</strong> services available on the Internet that delivers computing<br />

functionality on the service provider’s infrastructure. A cloud is a pool <strong>of</strong> virtualised<br />

computer resources <strong>and</strong> may actually be hosted on such as grid or utility computing<br />

environments [7, 59]. It has many potential advantages which include the ability to<br />

1

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