Performance study of dispatching algorithms in multi-tier Web architectures

The number and heterogeneity of requests to Web sites are increasing also because the Web technology is becoming the preferred interface for information systems. Many systems hosting current Web sites are complex architectures composed by multiple server layers with strong scalability and reliability issues. In this paper we compare the performance of several combinations of centralized and distributed dispatching algorithms working at the first and second layer, and using different levels of state information. We confirm some known results about load sharing in distributed systems and give new insights to the problem of dispatching requests in multi-tier cluster-based Web systems.