Based On The Web Service Wsdl Replaceability Validation Studies

SOA (Service-Oriented Architecture), as a new generation of software architec-ture, has loosely coupled, open, platform and language independent features. It pro-vides an effective solution for reuse of services and business integration and interac-tion of the cross-platform and has obtained considerable attention from both research and practice realms. As SOA gradually matures, services emerge at an ever-increasing pace in Internet and many of them have same or similar functions.In the distributed environment, one overlooked potential downside to SOA is the high possibility of component service failure. And when a single component goes down, the whole application could wreak havoc. To prevent an application from such disaster, it would be best to exploit plenty services on the Internet and establish the appropriate substitution mechanism to substitute the defective component, so as to the largest extent to maintain the success of the composite service. So service substitution means, in the context of composite services, one primitive service is replaced with a new one, which still guarantees essential characters of the composite service. Service substitution becomes a scientific issue.However, domestic and international previous related studies mostly are based on the assumption that component services and composite services require some kind of formal description of service behavior. But in the web service application, the most common form in SOA, the standard service contract cannot guarantee to satisfy this necessary condition. According to the specification of W3C and the majority of prac-tices of existing SOAP-based Web services, validation analysis of the services pro-vider, requestor and third-partly can only obtains the invoked interfaces and the input and output messages described in WSDL. So in the case of limited information from WSDL, this paper begins the study of service substitution.Aim at the above-mentioned problems, this paper does the following two aspects of the study and obtains the corresponding research results.1. Automatically extracts the service interface information and designs validation mechanism based only on WSDL to determine whether the component of composite service satisfies the given test conditions;2. Further depth to the service interactive messages on the basis of the service in-terface, and in more detail to determine whether the component of composite service satisfies the given test conditions; 3. Developed a prototype system and done the validation experiments of service substitution.