?WSDL for ReSTful applications?

One of the more useful things about web services endpoint is normally you can stick "?WSDL" on the end and get a description of the service. Now for rest full services you find that WSDL does work to described resource based services so sun came up with the WADL language.

The Jersey implementation will automatically generate this description for you simply GET application.wadl from the root of your service, here is an example for a simple hello world example: (More complicated example)

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<application xmlns="http://research.sun.com/wadl/2006/10">
    <doc xmlns:jersey="http://jersey.dev.java.net/" jersey:generatedBy="Jersey: 0.9-ea 08/22/2008 04:48 PM"/>
    <resources base="http://localhost:7101/Application1-Project1-context-root/">
        <resource path="/helloworld">
            <method name="GET" id="getClichedMessage">
                <response>
                    <representation mediaType="text/plain"/>
                </response>
            </method>
        </resource>
    </resources>
</application>

You can also request the WADL for a particular resource; but you have to use the OPTIONS method rather than a GET, here is a quite screen grab in the HTTP Analyzer. Annoyingly enough it doesn't use pretty formatting:

It is possible to use this description to generate a java client; but this is part of Jersey rather than part of the JAX-RS standard to be aware it is more subject to change.

Update: For those in the MS world the WCF REST framework uses a /help postfix to generate similar information. In a human rather than computer readable format from what I can see.