A distributed integrated request processing algorithm for QoS assurance in large-scale media-based systems

Abstract

In this paper, we discuss a comprehensive mechanism for distributed media request processing to achieve performance improvement and QoS enhancement in media-based application systems. The approach makes use of the proxy infrastructure to handle media requests in a widely distributed manner. The proxy server handles integrated request processing, including distributed admission control, batched patch, and prefix caching. A proxy assistant is designed to realize the proxy site request processing approach. A novel distributed admission control algorithm is proposed for the proxy assistant. It is based on the discrete time queuing system due to the consideration of batching. Also, to fully utilize prefix caching, we allow a request to stay at the proxy to wait for the disk bandwidth of the media server to become available before the cached contents are exhausted. Furthermore, a bandwidth allocation algorithm considering media systems with multiple servers is proposed. We develop a cost-effective approach for a proxy server to reserve bandwidth from the optimal subset of the media servers so that the final media delivery cost is minimal. Experimental studies show that our request processing approach, including all the proposed algorithms, significantly improves the network traffic, media server load, and response time.