摘要： 单个Web服务难以满足实际应用需求，如何组合已有服务形成新服务成为该领域的研究热点。现有的组合方法仅依靠输入和输出参数组合相关服务，很少考虑前提和后置条件的语义相关性。为此，提出一种基于目标递进的Web服务组合方法，采用前向链的搜索策略，建立基于条件的有向无环图，可有效利用输入、输出参数和前提、后置条件确定服务组合顺序，并成功处理控制流和信息流，解决当前服务组合存在的问题。通过将该方法应用到查找服务链的具体实例，验证了该方法的有效性。

关键词: Web服务, 前向链, Web服务组合, 基于目标递进

Abstract: Single Web services can not meet the needs of practical applications, how to compose existing services to form new services has become an important research in Web service domain. Current composition methods seldom consider the possible semantic similarities between their pre and post-conditions. To improve the situation, this paper presents a Web service composition approach based on goal narrowing. By introducing the use of a conditional directed acyclic graph, the approach can deal with complex interactions, containing control flow, information flow and pre/post conditions. Through a concrete example applying the approach to search for the service chain, the paper shows the effectiveness of the approach.

Key words: Web service, forward chain, Web service composition, based on goal narrowing

中图分类号: 

• TP311