Abstract
Web Services are a set of technologies designed to support the invocation of remote services by client applications, with the key goal of providing interoperable application-to-application interaction while supporting vendor and platform independence. The goal of this work is to study the real level of interoperability provided by these technologies through a massive experimental campaign involving a wide set of very popular frameworks for web services, implemented using seven different programming languages. We have tested the inter-operation of eleven client-side framework subsystems with three of the most widely used server-side implementations, each one hosting thousands of different services. The results highlight numerous situations where the goal of interoperability between different frameworks is not met due to problems both on the client and the server side. Moreover, we have identified issues also affecting interactions between the client and server subsystems of the same framework.