If you've ever used a library that has accurate MSDN-style API documentation, you know how useful it can be. There are lots of ways to create HTML documentation. But the easiest way that I've found is to use Sandcastle. It's an open source documentation generator from Microsoft that reads your assemblies (DLL or EXE files) and their XML Comments and automatically generates HTML documentation ...

WSDL is a specification defining how to describe web services in a common XML grammar. WSDL describes four critical pieces of data: In a nutshell, WSDL represents a contract between the service requestor and the service provider, in much the same way that a Java interface represents a contract between client code and the actual Java object.