Analyzing the Evolution of Web Services Using Fine-Grained Changes

In the service-oriented paradigm web service interfaces are considered contracts between web service subscribers and providers. However, these interfaces are continuously evolving over time to satisfy changes in the requirements and to fix bugs. Changes in a web service interface typically affect the systems of its subscribers. Therefore, it is essential for subscribers to recognize which types of changes occur in a web service interface in order to analyze the impact on his/her systems. In this paper we propose a tool called WSDLDiff to extract fine-grained changes from subsequent versions of a web service interface defined in WSDL. In contrast to existing approaches, WSDLDiff takes into account the syntax of WSDL and extracts the WSDL elements affected by changes and the types of changes. With WSDLDiff we performed a study aimed at analyzing the evolution of web services using the fine-grained changes extracted from the subsequent versions of four real world WSDL interfaces. The results of our study show that the analysis of the fine-grained changes helps web service subscribers to highlight the most frequent types of changes affecting a WSDL interface. This information can be relevant for web service subscribers who want to assess the risk associated to the usage of web services and to subscribe to the most stable ones.