Testing Web Services (WS) application systems is difficult and expensive. It imposes great challenges to existing testing methods, techniques and tools. This paper analyses the problems in testing WS applications and proposes a service oriented framework to solve the problems. It enables collaborations between various parties involved in the development of WS applications via service request and service providing. It also enables special testing services to be provided as WS to perform testing tasks on behalf of their customers. The key technical issues of the approach are discussed.