In order to improve the design and implementation quality of web service compositions,formal methods are used to model them and certain properties are verified.WCFA （web service interface control flow automata）is used to model web services,especially the control flow and possible interactions with other web services.A web service composition consists of a set of interacting WCFA.The global behavior of web service compositions is captured by NWA（nested word automata）.A variation of the depth-first search algorithm is used to transform a set of WCFA into an NWA.State formulae and call stacks at each node of NWA are computed by a path-sensitive reachability analysis.Safety properties,call stack inspection properties and pre/post-conditions of service invocations are described by assertions.Then verification of these assertions is carried out by an automated SAT tool.
In order to ensure e-government construction healthily,rapidly and orderly develop,an e-government maturity model（EGMM）is proposed based on a software capability maturity model （CMM）and a project management maturity model（PMMM）. Five levels of maturity in e-government development process are constructed,which include network infrastructure,information serving,information interactive,information sharing and comprehensive integrating.An index system of e-government maturity is put forward,and then an e-government maturity levels evaluation method is presented,which can provide clear,detailed and efficient decision information and investment directions of e-government for decision-makers.The EGMM and its maturity evaluation method are helpful for improving the construction of e-government.
