Abstract: Current reliability evaluation approaches lack a formal semantic representation and the support of incomplete or uncertain information. To fill this gap, Web service reliability ontology (WSRO) was developed. WSRO is mapped to a probability graphical model, and on this basis, the Web service reliability evaluation results can be obtained by the eau- sality reasoning. This approach can solve the problem of the lack of semantic description, assess the reliability of Web service, and lay the foundation for Web service auto-discovery, auto-composition and auto-execution. Experimental re- sups show that the approach is feasible,apphcable and effective.

Key words: Web services, Reliability, Ontology, l3aycsian network