Abstract: Replication strategy-based fault tolerance approaches for Web services have been widely used to guarantee the reliability and performance of service-oriented critical systems. Current approaches pay the major attention on performance-related qualities such as response time and failure rate. However, they ignore cost-related qualities such as the cost of service invocation and compensation, i.e., lack the consideration on cost-benefit analysis. This paper proposes a strategy-planning approach for Web service fault tolerance supporting cost-benefit analysis. The approach first defines the cost prediction formulas for the 9 common replication strategies based on the cost of service invocation and compensation, and then designs a strategy selection algorithm supporting cost-benefit analysis. The experimental results demonstrate that the proposed approach can significantly improve the effectiveness of the fault tolerance strategy with acceptable overhead.

Key words: Web service, fault tolerance, replication strategy, cost, service performance

摘要： 基于各种冗余策略的Web服务容错方法被广泛应用于面向服务的关键性系统的可靠性和性能保障。已有的Web服务容错策略选择方法只考虑服务响应时间和失效率等与服务性能相关的因素，而忽略了服务调用和补偿费用等成本问题，导致所选择的策略可能在成本效益方面存在不足。针对这一问题，提出了一种支持成本效益分析的Web服务容错策略规划方法。该方法针对九种常用的Web服务冗余策略给出了综合考虑调用和补偿费用的成本预测公式，并在此基础上给出了支持成本效益分析的Web服务容错策略选取算法。针对该方法的验证实验表明，所提方法能够显著提高Web服务容错策略的有效性，并且所产生的额外时间开销在可接受范围内。

关键词: Web服务, 容错, 冗余策略, 成本, 服务性能