Web Services Discovery And Integration In Workflow System

As infrastructures and systems supporting Web services are getting into mature, more and more organizations begin to integrate Web services as part of their business processes. They call for new workflow systems to support Web services integration and functionality of traditional workflow systems to be extended. However, problems such as Web services discovery, quality of service management of autonomous Web services, and semantic integration of heterogeneous Web services, need to be solved in Web-services-enabled workflow systems.The workflow-oriented Web Services Discovery and Integration Broker (WSDIBroker) we designed helps to solve these problems. WSDIBroker supplies two kinds of services: Discovery Service and Registry Service. The Discovery Service helps workflow modelers find suitable Web services through three steps: syntactical match, QoS metrics match, and semantic match, so that the result Web services recommended by the Discovery Service not only conform to the QoS requirements but also semantically agree with the interfaces of other tasks in the workflow. In the solution Web services' description files are required to include semantic information and QoS metrics, so we set a QoS model for workflow tasks and Web services, and defined a semantically-based Web service markup language-S-WSML.This paper focuses on the definition of S-WSML, which is the language basis of WSDIBroker, and the Web services discovery algorithms used in WSDIBroker, including syntactical match algorithm, QoS metrics match algorithm, and semantic match algorithm. We also demonstrated the architecture of the prototype system WSDIBroker and its integration into the workflow system ISFlow.