The Research Of A Web Service Description And Selection Mechanism Based On QoS Similarity

With the rapid development of Web Services,the number of Web Services is increasing very fast.For a capability Web Services request,usually there are a lot of Web Services fit for the need. But how to select one meets the user's quality need,the current Web Services discovery methods may not solve this problem.Therefore a new method based on Quality of Service(QoS) gains more and more people's attention.Now,the researches of QoS-based Web Service discovery are still in preliminary phase.They mainly focused on QoS quantitative match,but they are short of semantic match.So they have drawbacks in coverage and accuracy.By studying Web Services and the Semantic Web,based on the researches we have already had, we propose a Web Service description and selection mechanism based on QoS similarity(WSDSMQS).The main efforts are as followings.Initially we specify a QoS ontology(OWL-Q) and its vocabulary to describe QoS parameters. Using ontology as a bridge,both service providers and service requesters can describe the services clearly,which refines the match result in a semantic level.Then,the paper proposes a formal description model of QoS parameters for candidate services and requests.In the model,considering the users may not be experts in Web Service,we distinguish the necessary QoS parameters and optional QoS parameters,so the users won't miss any important parameters.Based on that,we propose a Web Service selection mechanism based on quality similarity (WSSMQS) which combines semantic match and quantitative match together.First by using the QoS ontology we constructed before,we process the different QoS parameters provided by providers and requesters semantically.Then we quantize all QoS parameters and choose suitable candidate services to construct a matching matrix.Because different QoS parameters have different value range,so we use three formulas to normalize the matrix.Then according to different weights,we calculate quantitative match degrees.Finally we rearrange the results in descending order,and give the result back to the requesters.In order to prove the feasibility and effectiveness of WSDSMQS,we implement a demo program(WSSDQS) to carry out simulation experiment.The experiment's result shows that the mechanism proposed in this paper can not only guarantee the correctness,but also improve the coverage.