When working with webservices there is hardly a way to get arround WSDL, the Web Service Description Language. Still a lot of developers tend to think that they don’t need to know the interna, because tools like java2wsdl generate the WSDL file for them. So why bother with the details? Well, as long as you code first this might be true in parts, but the moment you have to hit a different development path, namely contract-first, things change. Now you have to create the WSDL file and respective XML schema first. Therefore it can’t be wrong to know how the WSDL clock ticks.
We will concentate on the WSDL 1.1 revision, even though version 2.0 is a W3C recommendation since March 2006 (but not wide spread one). After a short overview we will walk through the WSDL components by example. Please note, that you need to have a basic understanding of XML and XML schema for our walk.