Today i read the description of WADL from wikipedia "The Web Application Description Language (WADL) is an XML-based file format that provides a machine-readable description of HTTP-based web applications".
Here what is the meaning of "Machine readable description of HTTP based web applications"?
WADL is for RESTful WS what WSDL is for SOAP-based WS. I think it's primarily used for WS implemented in Java; its home can be found at http://wadl.java.net/. The JAX-RS reference implementation Jersey uses it.