Abstract: A net unit model of service cluster was defined and a Web service discovery method based on the model was proposed. First, service clustering was completed based on the semantic similarity of functional description and the pa- rameters. Second, the net unit models of service clusters were built with the unified labels of service parameters, and then service cluster parameter matrix was constructed with standardize treatment. And finally, service discovery was re- alized by using the service cluster parameter matrix On the base of Petri net, the formal model of service cluster was proposed for the first time, and a quick service discovery was realized. I}he results indicate that the model to construct service clusters is effective and reasonable. Compared with the traditional service discovery methods based on the pa- rameter matching, this proposed method can effectively reduce the number of parameters matching times and improve the service discovery efficiency.

Key words: Parameter uncertainty, Semantic similarity, Service clustering, Net unit model, Parameter matrix, Service discovery