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Problem statement: With fast spreading of web services technology over the Internet, the quality aspects of a web service has received significant attention to the practitioners. The quality of web service includes both functional and nonfunctional details. In order to provide the correct and meaningful information to web service consumer, sometimes there is a need to compose existing web services in order to create new web service. Approach: We have proposed a Quality of Service (QoS) broker based process model for Dynamic Web Service Composition (DWSC). The QoS broker in the proposed model is responsible for web service collection, selection, optimization and composition based on the service consumer's requirements. It also verifies and certifies the functional and QoS specifications provided by service provider at the time of web service registration before publishing it in Universal Description, Discovery and Integration (UDDI) registry. The detailed working of QoS broker is also presented in the study with functionality of each component. We will also discuss the process flowchart for new web service registration and web service composition at runtime. Results: The proposed QoS broker based model for dynamic web service composition solves the problems associated with quality of web service. It also prevents the central repository from malicious service provider to publish wrong information. Conclusion: The QoS broker-based process model for dynamic web service composition guarantees the quality of delivered service to web service consumers and improve the efficiency of composition.

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Web service composition has gained tremendous interest with emerging application development. Automatic service composition is a key aspect in overcoming runtime problems that arise due to dynamic nature of runtime environment. In SOA, applications are formed through the combinations of independently developed web services that lead to emergence of different dependencies among the component services. The challenge of web service composition is to manage such kind of dependencies among web services when there is large number of services. In this paper, an inheritance based Bully Election approach is proposed for analyzing dependency among services and generating automatic service composition plan. It also identifies the coordinator service on which the execution of other services is dependent. Experimental result shows that the proposed approach is able to reduce the composition time complexity by including only the selected services on the composition plan.