Web Services are self-describing, modular applications. The Web Services architecture can be thought of as a wrapper for the application code. This wrapper provides standardized means for describing the Web Service and what it does, publishing it to a registry so that it can be easily located, and exposing an interface so that the service can be invoked - all in a machine-readable format. What is particularly compelling about Web Services is that they can be accessed by any client that understands XML, regardless of the platform, language, or object model. This book provides a snapshot of the current state of these rapidly evolving technologies, beginning by detailing the main standards that underpin the Web Services model (SOAP, WSIDL, and UDDI) and then putting this theory to practical use in a wide array of popular toolkits, platforms, and development environments. The technologies presented in this book provide the foundations of Web Services computing, which is set to revolutionize Distributed Computing as we know it. This book is for developers wanting to learn what Web Services are, and how to create, register, and deploy them. In teaching the core technologies, we assume a basic knowledge of XML from the outset.