What Is This Book About? This is a book about Web Services. Web Services are still more like a movement than a mature technology. The movement is motivated by a vision of a semi-auto- mated Web that can support long chains of interactions between autonomous agents. There are three important components to that vision. One is interoperabil- ity: a service can have clients (agents) from any platform, in any language. Another is autonomy: an agent can discover the services it needs from their published descriptions that include both what the service can do and how it does it (the interfaces of...