XML and the concept of objects and remote objects are the driving force behind Web Services. The concept of Web Services comes from the idea of Remote Procedure Call (RPC), which is a simple way of calling methods from across a network. The problem with RPC was that every vendor had a different standard for transporting the data. By using XML, the data in Web Services now moves in a predictable manner across a network or the Web.
Section I focuses on introducing you to the concepts and standards that make up Web Services. This ranges from how Web Services compare to other remote object technologies to the underlying XML standards that comprise Web Services such as WSDL, SOAP, and UDDI. The general concepts of XML are covered in Chapter 2 in order to give you a quick reference for the terms used in later chapters.