Service Oriented Computing(SOC) is becoming a major paradigm for developing next generation of software systems, and one of the major challenges of Service Oriented Computing is testing interactions and collaborations among the distributed and dynamically integrated web services. To support automated test of web service‟s collaborations, a formal specification is needed. This thesis proposes a specification of web services collaborations based on Web Services Choreography Description Language (WS-CDL). We identify the basic constructs that can be found in any web services collaboration, and we mapped them to the new WS-CDL based language (WS-CDL+). Finally, A scenario of web services collaboration is developed and specification in WS-CDL+ is provided. This work builds a foundation for automated web services testing in a service oriented computing environment.