Efficient Support for Content-based Routing in Web Server Clusters

Clustered server architectures have been employed for many years on the Internet as a way to increase performance, reliability and scalability in the presence of the Internet's explosive growth. A routing mechanism for mapping requests to individual servers within cluster is at the heart of any server clustering techniques. In this paper, we first analyze the deficiencies of existing request-routing approaches. Based on these observations, we argue that the request routing mechanism in a cluster-based server should factor in the content of a request in making decisions. Thus, we designed and implemented a new mechanism to efficiently support content-aware routing in Web server clusters. With this mechanism, we also built in a number of sophisticated content-aware intelligence for making routing decision. Performance evaluation on a prototype implementation demonstrates substantial performance improvements over contemporary routing schemes. The proposed mechanism can also enable many new capabilities in cluster-based servers, such as sophisticated load balancing, differentiated service, special content deployment, session integrity, etc.