Scalability of content-aware server switches for cluster-based Web information systems

A cluster-based architecture with a front-end Web switch and locally distributed servers seems the most appreciated solution to face the ever increasing demand for complex services offered through Web interfaces. The complexity of the novel services is often related to the possibility of content-level identification and personalization that can be achieved through a content-aware front-end component. It is common belief that content-based operations prevent the scalability of the Web cluster, to the extent that a content-aware switch alone is seldom used as the front-end of a popular Web site. In this paper, we demonstrate that a careful design and optimized implementation choices based on a modern PC-based architecture can give a Web switch with content-aware functionality and very limited overheads. We present the design and prototype implementation of a so called one-way system based on Linux kernel, single CPU and SMP-based architectures, for HTTP/1.0 and HTTP/1.1 protocols. The experimental results confirm that the proposed solution is extremely scalable, thus making a content-aware Web switch a viable solution to the performance requirements of the majority of cluster-based architectures.