Service organisation and information consistency for service grid
International Journal of Web and Grid Services
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As web-based transactions become an essential elementof everyday corporate and commerce activities, it becomesincreasingly important that the performance of web-basedservices be predictable and guaranteed even in the presence of wildly fluctuating input loads. In this paper, we propose a general implementation framework to provide qualityof service (QoS) guarantee for cluster-based Internet services, such as E-commerce or directory service. We describe the design, implementation, and evaluation of a webrequest distribution system called Gage which can provideevery subscriber with distinct guarantee on the number ofgeneric web requests that are serviced per second regardlessof the total input loads at run time. Gage is one of the firstsystems that can support QoS guarantee involving multiplesystem resources, i.e., CPU, disk, and network. The front-end request distribution server of Gage distributes incoming requests among a cluster of back-end web server nodesso as to maintain per-subscriber QoS guarantee and loadbalance among the back-end servers. Each back-end webserver node includes a Gage module, which performs distributed TCP splicing and detailed resource usage accounting. Performance evaluation of the fully operational Gageprototype demonstrates that the proposed architecture canindeed provide the guaranteed request throughput for different classes of web accesses, even in the presence of excessiveinput loads. The additional performance overhead associated with QoS support in Gage is merely 3.06%.