Research And Application Of Service Composition Based On Workflow In E-Government System

The E-Government is an effective way to enhance efficiency, improve service quality and share information for the government. With development of technologies for E-Government, a series of information systems have been developed, which are built on different developing platform by different programming languages. They normally operate independently and are hard to cooperate with each other and thus form many"information islands"which prevents E-Government from further developing. So it is urgent to integrate these isolated application systems, to share information and to avoid redundant construction nowadays.To solve the above problems, the E-Government systems should be integrated, but the traditional integration technologies are often platform-dependent, so it can't meet the requirement of loose couping for E-Government systems. Service-Oriented Architecture (SOA) is a component model that inter-relates an application's different functional units, called services, through interfaces and protocols between these services, thus realize loose couping integration. This paper took advantage of the idea of service composition, and defined the workflow process through extended XPDL, and carry out the workflow process definition through lightweight workflow engine based on related structure. Finally, this paper designed and implemented the major modules of this cooperative E-Government system.This paper has accomplished the following tasks:①It took research into related technologies about Web services and workflow. It analyzed various service composition methods, and their suitable situation.②It analyzed the Web service selection based on QoS, and improved the model of QoS parameter computing. It provided better results to meet the requirement of user through improved model of Qos parameter computing.③It extended XML Process Definition Language (XPDL), which is a standard specification of Workflow Management Coalition (WfMC). The extended XPDL supported the definition of Web services. Finally, this paper made a comparison between extended XPDL and BPEL.④It researched two traditional service implementation model: centralized service implementation model and peer to peer service implementation model. This paper proposed a service implementation model based on their advantages and disadvantages. ⑤It applied the Web service composition based on workflow in E-Government system. It designed a cooperative E-Government system framework according to practical requirement, analyzed and designed the major modules of this system.⑥It implemented the major modules of this system and verified the rationality and feasibility of the system framework through test and application, which proved that the intra-department cooperative office work and flexible business flow can be implemented by Web service composition based on workflow.