Verification for Time Consistency of Web Service Flow

Non-functional property verification (such as time consistency) for Web Services (WS) flow has become indispensable since many WS for e-business exist in real world with temporal context and depend on many external restrictions like executing time and consuming cost etc. Unfortunately, current researches mainly focus on the modeling, analyzing and verifying of WS process, while ignoring the non-functional factors. Aiming at verifying time constraints in service flow, the paper presents a method for verifying time constraints consistency in WS flow. By building time ontology based on DAML_Time, the OWL_S(Ontology Web Language for Web Services) is extended with time constraints, which expresses time information of WS flow clearly and roundly. Then the annotated OWL_S is transformed to formal model TCPN (Time constraints Petri Net). By verifying property of TCPN, the time consistency of WSflow can be verified according to the result of verification algorithm. A composite WS is taken as an example to illustrate the process of verification.