Abstract: The paradigm of Web service composition becomes important for distributed Internet applications.Many of them require continuous providing of service capability.Therefore，fast recovery of composite service after failure is needed.To achieve that goal，decentralized composition model is utilized which has a central engine and multiple engines，and recovery mechanism is developed based on it.Composite Web service can be recovered by cooperation of central engine and local engines.It can also keep properties of Web service，guarantee exactly-once semantics execution and reduce I/O cost.

Key words: Web service, composition, recovery

摘要： Web服务合成已成为一种重要的分布式网络应用开发模式。网络应用要求Web服务具有较高的可用性，进而要求Web服务必须具有快速恢复的特点。基于分布式Web服务合成的模式开发合成服务的恢复机制适合网络环境下的服务交互方式。分布式Web服务合成模式中包含有一个中心合成引擎和若干本地合成引擎，恢复机制由中心合成引擎与本地合成引擎合作实现，确保了唯一执行语义，同时又可保持Web服务的特性，并降低I/O代价。

关键词: Web服务, 合成, 恢复