Generating test cases for web services using data perturbation

Web services have the potential to dramatically reduce the complexities and costs of software integration projects. The most obvious and perhaps most significant difference between Web services and traditional applications is that Web services use a common communication infrastructure, XML and SOAP, to communicate through the Internet. The method of communication introduces complexities to the problems of verifying and validating Web services that do not exist in traditional software. This paper presents a new approach to testing Web services based on data perturbation. Existing XML messages are modified based on rules defined on the message grammars, and then used as tests. Data perturbation uses two methods to test Web services: data value perturbation and interaction perturbation. Data value perturbation modifies values according to the data type. Interaction perturbation classifies the communication messages into two categories: RPC communication and data communication. At present, this method is restricted to peer-to-peer interactions. The paper presents preliminary empirical evidence of its usefulness.