Abstract: The development of Web service technology provides us a kind of platform-independent, self-described, localion-transparent software module. Utilizing Web service composition technology, business demand can be met ctuickly and flexibly. As Web service composition becomes more and more complexity, design of composition process became more and more error-prone. We put forward a model for Web service composition description based on extended colored Petri net. This model is independent of any process description languages, supports hierarchical process description and

Key words: Hierarchical colored Petri net, Model driven architecture, Web service composition, Correctness analysis