Constructing zero-loss Web services

Modern Web services must support large and rapidly growing user populations, and remain available 24 hours per day, 7 day per week. Server cluster is the most promising approach to address this challenge. In this paper, we further augment the server-cluster schemes with a novel mechanism that enables a Web request to be smoothly migrated and recovered on another working node in the presence of server failure or overload. The new mechanism provides a powerful solution to fault tolerance and dynamic load-distribution for Web services. The administrator can explicitly specify some services to be guaranteed for fault-tolerance or higher performance support. We present the details of our design, implementation, and performance data. The performance results show that the proposed mechanism is efficient and with low associated overhead.