On PHPMaster.com today they've posted the second part of their series looking at creating a SOAP web service with NuSOAP. (Part one is here)

In this article we’ll talk about what WSDL files are and how to use them. I’ll show you how to quickly build your WSDL files with NuSOAP and incorporate a WSDL file into the SOAP server and client examples from the first part.

He introduces WSDL files, the specially formatted XML definitions that tell SOAP clients what's available on the service and includes some markup as examples. Creating one from scratch ca be a hassle, so it's handy that NuSOAP generates one for you from your server class. He includes sample code to create this generated file and how to create a SOAP client pointed to the PHP script to get the result.