Research And Implementation Of Human Task Performing System Based On Asynchronous Pattern In Bpel

As the development of the web technology and enterprise informationization, more and more enterprises are using Service-Oriented Architecture (SOA) to intergrate their existing information systems, achieving the sharing of information and the collaboration of working among different systems. Web Service is the core technology of SOA. Interaction between heterogeneous systems in the enterprise can be achieved by web service. The function of a single web service is limited. It is necessary to compose several web services to provide stronger functions in many real-world applications. BPEL is a kind of language which describes web service composition as a business process. It composes several independent services together and constructs a business process. BPEL focuses on the automatical running of business process, but do not support the interaction between processes and users. However, many processes in real-world applications are not fully automatical operation, which require user involvement.To solve the problem that BPEL doesn't support user interaction, this paper improved the language used to define human tasks and the human task performing system architecture in the existing research. A human task transformation program was designed and implemented to automatically transform human task into an asynchronous invocation to a human task manager outside of the BPEL engine. The process definition file can be deployed into any engine that support the standard BPEL and it is needless to modify or extend the engine. The human task manager was also designed and implemented to maintain human tasks and act as a bridge between the process and user.This paper has accomplished the following tasks:①It analyzed the current domestic and international researches about the user interaction and related technologies of BPEL. It analyzed the advantages and disadvantages of related researches.②It analyzed the process of user interaction, and improved the human task definition language in BPEL of the existing research, adding the definition of the deadline of the waiting of BPEL process, task claiming and task escalation.③It researched the synchronous and asynchronous pattern of the invocation to web services in BPEL, and improved the human task performing system architecture in the existing research. In this system there was a human task manager outside of the BPEL engine to maintain human tasks. Processes interacted with human task manager with aysnchronous message pattern which can support the long-term running of human tasks better.④A transformation program was designed and implemented which could be used to transform the invoke activity including human task definitions into into an asynchronous invocation to the human task manager. The system prototype of the human task manager was designed and implemented too. JAX-WS was used to encapsulate functions of the human task manager as a web service which could be called by processes and clients.⑤A car loan approval process which need user interactions was used to verify the system. The result proved that the system is reasonable and feasible, and user can affect the running of processes.