EDG-DCR:一种基于扩展有向图Web服务组合关系描述方法

A Description Approach to Web Service Composition Relationship Based on Extended Directional Graph

Web服务组合是充分利用已有的Web服务,生成满足不同用户实际需要的组合服务的重要技术,Web服务组合关系的描述是Web服务组合的基础。目前,Web服务组合关系描述主要有两类方法,一是基于有向图的描述方法,二是基于Petri网、语义的描述方法。前一种方法简单,但不能描述所有的组合关系;后一种方法虽然能描述所有的组合关系,但是它们的组成元素过于复杂,用户难以理解和使用。文章以工作流模式为基础,提出一种基于扩展有向图的Web服务组合关系描述方法,使得其可以描述所有的组合关系。该描述方法使用XML Schema表示组合关系,保证描述过程的简单性、开放性和可扩展性。

Web service composition is the technique of composing arbitrarily complex services from relatively simpler services available over the internet. Description of Web service composition relationship is the basis of Web service composition. The existing methods on describing the composition relationship can be categorized into two types., the directional graph based, and semantic based. The former is simple, but it can not describe all of the composition relationship. The latter could describe all of the composition relationship, however, it is quite difficult to understand and use for developers due to the complexity of semantic information. In this paper, a new description approach is proposed to Web services composition relationship based on the extended directional graph （EDG-DCR）. EDG-DCR not only could describe all of composition relationship, but also be quite easy to understand and use for developers due to its simple elements. Finally, a Web service composition description tool is implemented, which can automatically create XML-formatted description files.