The Study And Implementation Of Web Services Asynchronous Invocation Model

Along with the Intranet/Internet having been developed swiftly, computer technology has already got more and more widespread and thorough application in such aspects as production, management and commercial affair of enterprises. The demand of Service Oriented Architecture (SOA), Dynamic Electro-Business (DEB) and Enterprise Application Integration (EAI) is thereupon springing up. Web Services has got broad concern and support as the technology of a new basic platform of SOA, DEB and EAI, and has been been actually obtains many applications. But because Web Services, as a distributed computing platform, is still imperfect on its service call models which implemnets now, therefore has not got the large-scale industrial application throughout.Although Web Services can support many kinds of network communication protocols, because HTTP has many advantages such as widespread usage, ability of passing through firewall and etc, makes Web Services based on HTTP (Web Services/HTTP) become the most general adoption actually. But under this mode, the service call models have only been implemented in one-way and synchronous request/reponse model, and as to Asynchronous Invocation Model (AIM) and Message/Events Service (MES), it still have not uniform realization and standard. This thesis researches how to consummate AIM of Web Services/HTTP, designs and realizes the all of AIM including Callback, Polling, Callback with Acknowledge (ACK) and Polling with ACK.Referred to existing research results of Web Services AIM, the pattern based on MultiThreading Synchronous Invocation (MTSI), which includes network connection of each request and network connection pool subpattern, is designed and realized to implement AIM. Because the pattern of MTSI exists many shortcomings such as heavy threads load on client operation system, long system delay time, taking too many network resources and low resource usage rate, the novel pattern based on Asynchronous SOAP (Asyn SOAP), which includes service thread of each request and serice threads pool subpattern, is proposed and realized to overcome the defects of MTSI. Meanwhile, Petri Net is used to describe these two system designs of MTSI and Asyn SOAP, then the maturity theory of Petri Net is imported to analyse and prove the related properties of the system designs, which mainly includes: whether exists dead locks and live locks, and whether the system can achieves the final expected state as well as whether has the states which are not hoped. Through the analysis and verification, the correctness of these two system designs is proved.Then referring the user program interface of Asynchronous Method Invocation (AMI) in CORBA, the user interface of Web Services/HTTP AIM is defined. Based on existing tool of WSDL to client program stub of Web Services in java, the new expanded tool of WSDL2Java, which can automatically generate the corresponding client stub of AIM according to WSDL, is implemented. Finally, under the campus network of CERNET and the Internet of telecom, the functions and performance items (includes average system delay time, throughput of system and average client number that the server can accepts concurrently) of the two prototype systems based on MTSI and Asyn SOAP pattern are experimented, then the test result is compared and analyzed in detail. According to the function experiment, either pattern of MTSI or Asyn SOAP can correctly implements AIM, and the performance test result has proved that the pattern of Asyn SOAP is superior to MTSI in many aspects.