As the Web gradually evolves into the semantic web, the World Wide Web consortium (W3C) recommends that web ontology language (OWL) be used to encode semantic information content over the Web. Semantic web is an essential infrastructure to enhance Web to obtain better integration of information and intelligent use of web resources. Moreover, a web service is annotated by web ontology language for service (OWL-S) to form a semantic web service that, however, is a static description. The OWL-S based semantic web services thus are reactively invoked by users. How to dynamically coordinate, composite, or discover the services is an important issue.