Building a .NET Web Service

Write a class with attributes (comments) that identify it as a web service with exposed methods.
.NET uses these to create WSDL document.
Client adds service as web reference in Visual Studio .NET, or runs WSDL.exe to create stubs.
.NET uses WSDL file to generate proxy (stub) classes.
Client instantiates proxy class and calls methods on it.
Proxy class converts it to a SOAP message and sents it.
Proxy class receives SOAP reply, parses it, and returns value to client.