How can I generate WADL for REST services

If you are using Jersey then url to wadl would be something like

http://localhost:8080/applicationname/application.wadl

You may need to add the resource base into the url e.g.

http://localhost:8080/applicationname/resources/application.wadl

http://{host}:{port}/{context_root}/{resource}/application.wadl 

substitute values for host, port, context root and resource.

In the past I've used Enunciate (GitHub repository).

It's a build-time tool that generates Interface Definition Documents (WADL, WSDL, etc) automatically for you. It's really easy to integrate it in your Maven build.