Research On Web Service-Based Workflow Of Dynamic Virtual Enterprise

Aggravating market competition requests enterprises should enhance their own core competence according to their characteristic, concentrate their main attention on the research of core technoloties and manufacture of core products, reform their backward manufacturing pattern. It makes enterprises must outsource other non-core competence tasks to other enterprises. And virutal enterprise comes into being at this moment. The workflow technology is an effective method of controlling and managing the fixed business process of single enterprise. Along with the tendency of enterprise's globalization and rapid development of information technology, especially the Internet and the World Wide Web, business processes gradually extend outside the enterprise, many business processes need to be completed by several enterprises cooperatively. The traditional workflow technology that manages single business process within one organization, it can not support the cross business processes of virtual enterprise well and shows its limitations while it confronts with such business processes management requirements. The new features of business processes require the WFMS should have distributed and loosely coupled architecture and be able to deal with workflow processes which across multiple organizations in a process-oriented manner.As a distributed computing environment, SOA and Web Services can provide a communication infrastructure for implementing distributed workflow management system. Therefore the extension of workflow management systems to manage virtual enterprise business processes seems to be a promising solution.On the basis of analyzing many famous projects, products and specifications, we have done much research on some key technologies in web services-based workflow of dynamic virtual enterprise which includes the following aspects:(1) According to the new features of business process brought by macro trends in business and technology, the opinion that traditional workflow management systems must break through their limitations to satisfied the requirement of proeess management is expressed. In addition, it is stated that distributed architecture is the direction in workflow management system development. Furthermore, SOA and Web Services are proved as suitable infrastructure of fully distributed and loosely coupled WfMS.(2) Through analyzing the running mechanism of dynamic virtual enterprise workflow and realization mechanism of virtual enterprise, an information architecture of virtual enterprise based on Web services is proposed. By extending WfMC's WPDL, a web services-based workflow of dynamic virtual enterprise is also presented. The extension includes adding the concepts of events and rules into WPDL, introducing the connector construct and supporting Web services requests.(3) Based on the above workflow process model a code generator is designed. It generates run-time workflow structures and activity code. Workflow structures and activity can be modified at run-time. It can realize the flexibility of the workflow of dynamic virtual enterprise effectively.(4) Converting the problem of selecting virtual enterprise partner into the problem of dynamic selecting, binding and evaluating Web service resources. Web services and web service request is specified and registered according to the web service definition template. We adopt the syntax and semantics of the Constraint-Based Requirement Specification Language to specify attribute and inter-attribute constraints on the attributes of the web service. In case that there are multiple service providers can satisfy the requests, we take the non-function attribute of candidate Web services as evaluation criterion and select the optimum Web service based on the fuzzy analytic hierarchy process method.(5) Transaction management is introduced into the web service-based workflow of dynamic virtual enterprise. Based on the present research of the transaction of workflow, we find the tranditional transaction model is not suitable for web service-based workflow of dynamic virtual enterprise. So a new transaction model of workflow based on the direc relation and indirection relation is presented in the paper.