Author: Xavier Vilajosana Guillén
Programme: Doctoral Programme on the Information and Knowledge Society
Language: English
Supervisor: Dr Joan Manuel Marquès
Faculty / Institute: Internet Interdisciplinary Institute (IN3)
Subjects: Computer Science
Key words: Allocation of computer resources, Economic models, Grid computing
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Summary
The thesis presents an approach to on-demand capacity expansion in communities of Internet users that aggregate their resources to achieve a common objective. Such communities are emerging as forms of organisation taking advantage of increasing broadband access and computational capacity. Volunteer computing such as SETI@home, collaborative grids such as OurGrid and LaCOLLA, Ad-hoc and peer-to-peer grids, such as P-Grid and the XGrid project from Apple, open grids such as those addressed by SORMA and Grid4All and many other approaches of grid computing based on virtual organizations are the focus of our work. These systems are characterized by the purpose of their participants, ie to achieve a common objective taking advantage of the aggregation of other resources. The cited systems, in contrast to high-performance computing grids, are open to new participants, which makes their behaviour unpredictable and dynamic, and resources are usually connected and disconnected spontaneously. While the critical aspect of high-performance grids is computational performance, stability and availability are the main issues for the systems addressed in this work. The thesis homogenises the concepts of those paradigms under the term contributory system, which is used throughout the thesis to refer to the systems where users provide their resources to be used collectively in order to achieve a common objective. Resource expansion in contributory systems is required so as to increase the limited capacities of ad-hoc collaborative groups under unexpected load surges, temporary resource requirements, or other policies defined by the objectives of the virtual organization that they constitute.
Four aspects are addressed by the dissertation. First, it identifies the main properties and applications of contributory systems and motivates the need for infrastructures to enable on-demand resource expansion. This goes in the direction of utility computing trends which are main business lines for IT companies. Thus the thesis proposes the on-demand provision of idle resources from the extremes of the Internet, other virtual organizations or resource providers to those organizations that have resource needs. In this work, resource allocation is handled by market models which provide efficient but simple mechanisms to mediate the allocation of resources. This proposal offers new emerging opportunities to Internet users to do business on the Internet by selling their idle resources. In addition, this allows small communities to grow and to bring super-computing capacities to Internet end-users.
Secondly, the thesis describes semantically computational resources so as to build a common knowledge about the Internet's resources. The semantic description enables a common understanding of the nature of resources, permitting the pooling and aggregation of distinct types of technologies while maintaining the same semantics. This makes applications and resource management frameworks independent of the real nature of the resources which we claim is a fundamental aspect in keeping resource management independent of the dynamics and evolution of technology in computational environments, such as in contributory systems. A semantic description permits the development of generic specifications to provide bid and offer descriptions in computational markets.
Thirdly, the architecture for on-demand resource expansion in contributory systems is presented. It has been designed to provide the main functionalities to on-demand provision of resources through markets to scenarios characterized by dynamism, evolution, and heterogeneity. The architecture provides the main market-oriented functionalities and enables dynamic and on-demand execution of market mechanisms.
Finally, a specific grid-oriented market mechanism is presented. The approach is motivated by the unsuitability of current auctions to efficiently allocate time-differentiated resources (usually provided by many different resource providers) such as most of the resources in a contributory system.
The thesis builds a roadmap to achieve flexible and decentralized resource expansion in communities where resources are shared by their participants by analysing the main scenarios where it can be applied, providing the semantics and specification to enable the description of the user's requirements, proposing a flexible and configurable architecture to deal with on-demand resource expansion in virtual organisations, and proposing a specific mechanism adapted to trade computational resources.