Research And Implementation Of Web Service Dynamic Composition Mechanism

How to combine existing web services to meet more complex application requirements is an urgent problem to be solved in engineering practice.Web service composition can be divided into static composition and dynamic composition.Static composition has many problems,such as abnormal overall system function due to atomic service failure,composite service QoS can not dynamically meet user needs and so on.Therefore,it is necessary to study and build a service dynamic composition mechanism.In view of the above problems,this paper studies from the following three aspects:(1)The architecture design of web service dynamic composition mechanism and the construction of JUDDI research platform.Through the research and analysis of the current mainstream web service dynamic composition architecture,this paper designs a QoS based web service dynamic composition framework,which mainly includes:UDDI registry extension design,QoS guarantee component design,BPEL4 WS business process design,business process template library design,BPEL4 WS engine module design and database design.The experiment built a private JUDDI server and obtained a large number of real and effective web service data,which provided a rich set of candidate services for the combined coarse-grained web services.(2)Research and implementation of QoS driven web service dynamic discovery mechanism.This paper proposes a two-stage web service dynamic discovery mechanism based on keywords and quality of service.The first stage: from the perspective of function,screen out the correct web service that meet the needs of users through keyword search;In the second stage,based on the filtered service set,the QoS of web service is weighted according to user preferences,and then the QoS based user service recommendation is completed.Experiments show that the query efficiency of the two-stage service discovery mechanism is higher than that of the traditional keyword query method.(3)Design and application of dynamic composition mechanism of web service.Firstly,the improved genetic algorithm is used to obtain the approximate optimal solution of composite services under QoS global constraints;Secondly,taking tourism service as the application scenario,the module design of business process is carried out through BPEL4 WS process designer,the definition of business process template is realized,and the operation of composite services is realized through BPEL4 WS engine;Finally,a prototype system is used to test the dynamic service composition mechanism to verify its correctness and availability.Based on a large number of real and effective web service data and JUDDI experimental platform,this paper comprehensively studies and verifies the correctness of the proposed two-stage service discovery mechanism and QoS based web service dynamic composition framework,and preliminarily realizes the dynamic replacement of services after system functions are abnormal and the dynamic composition of services driven by QoS.