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With the evolvement of the e-commerce, the Internet is undergoing substantial changes from a communication and browsing infrastructure to a medium for conducting business and selling services. These changes place the Web server at the center of the e-commerce infrastructure with increasing requirements for providing service differentiation and performance assurance. To that end, Web servers must have mechanisms and policies for establishing and supporting quality of service (QoS). In this paper, a Web server prototype with priority based QoS control mechanisms, called QoS Apache, is implemented. A performance testing platform is established, and the performance measurement software httperf is used to test the popular Apache and the QoS Apache. The performance evaluation results show that the QoS Apache server can provide different types of requests with differentiated Web QoS, in comparison with the popular QoS-unaware Apache.

In the multi-service wireless networks, the bandwidth asymmetry is the distinctive characteristic. To avoid wasting uplink and downlink bandwidth in asymmetric network, admissible region for the nonreal-time (NRT) calls has been proposed. But in that scheme the static guard capacity for RT and NRT calls cannot adapt to traffic variation. In addition, the differentiated QoS services to users are not considered. In this paper, we propose an adaptive guard channel reservation (AGCR) scheme, which has the following novelties: i) the guard capacity for each class is dynamically adjusted so as to adapt to dynamic traffic, ii) the blocking probabilities of classes with higher priority are kept below certain targets and iii) differentiated QoS services to users are provided by maintaining the blocking probability ratios over different classes at the predefined targets. Simulation results have demonstrated the proposed AGCR scheme can keep the blocking probabilities of classes with higher priority below certain targets, track the ratios close to the targets well while maintaining a high bandwidth utilization

The guard channel scheme in wireless mobile networks has attracted and is still drawing research interest owing to easy implementation and flexible control. However guard channel schemes can not adapt to changing traffic loads because of static reserved guard channels. Therefore dynamic guard channel schemes have been proposed in the literature to adapt to varying traffic load. This paper presents a novel control-theoretic approach to dynamically reserve guard channels called PI-guard channel (PI-GC) controller. Experiments show that our proposed scheme can maintain the handoff blocking probability (HBP) to a predefined value while it still improves the channel resource utilization

Grid computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications, and high-performance orientation. A Grid integrates and coordinates resources and users that live within different control domains with the goal of delivering nontrivial quality of service (QoS). Consequently, task management and scheduling is of central importance for the Grid-based systems. In this paper, we model the task dispatching and selecting on the distributed Grid computing system by a multiserver multiqueue (MSMQ) model, and propose a modeling and analysis technique based on Stochastic Petri Net (SPN) methods. An approximate analysis technique is also proposed to reduce the complexity of the model.