Nested Web Service Interface Control Flow Automata

The formal definition of NWCFA (nested Web service interface control flow automata) is presented as the model of web service compositions (possibly with recursion). WCFA (Web service interface control flow automata) are used to model individual Web services, which form a composition. WCFA focus on the control flow and service invocation behavior. Then a NWCFA will be constructed to describe the global behavior of the composition. NWCFA use the concept of nested words to deal with recursion. An example is used to illustrate the usage of WCFA and NWCFA. Temporal properties can be verified through an automata-theoretic method.