Abstract: In the traditional service-oriented environment,service customers and service providers need to complete service binding through the UDDI server which cannot provide a asynchronous,reliable and manageable process．This paper introduced NServiceBus which is a open source service bus to provide a kind of asynchronous communication model.The centralized management and service quality control for registration services can effectively improve the system service calls’ flexibility and extendability．In addition,this paper analyzed message forwarding mechanism of NServiceBus open source service bus,and proposed a kind of service response time model to forecast overload condition of current system in high concurrent access and provide overload protection.This paper also designed and implemented a kind of self-adaptive priority queuing to provide hierarchical scheduling of service request,to a certain degree to ensure service response time and improve the system response rate．Finally the evaluation experiment and contrast analysis in the application of actual project prove validity and practicability of this method to improve the performance of NServiceBus service.

Key words: SOA,Web services,NServiceBus,Overload protection,Message queue