Software testers are confronted with nice challenges in testing net Services (WS) particularly once group action to services owned by alternative vendors. They need to handle the of implementation techniques utilized by the opposite services and to satisfy a large range of check needs. A fictitious car insurance broker CIB is developing a web-based system that provides a complete service of car insurance. Addressing these problems, this paper proposes a framework of collaborative testing in which test tasks are completed through the collaboration of various test services that are registered, discovered, and invoked at runtime using the ontology of software testing STOWS. The composition of test services is realized by using test brokers, which are also test services but specialized in the coordination of other test services. The ontology can be extended and updated through an ontology management service so that it can support a wide open range of test activities, methods, techniques, and types of software artifacts.