WADL OpenSourced - Describing RESTful Web Services
By pelegri on Sep 30, 2006
Typed XML over HTTP has many benefits: it combines the properties of HTTP with the simplicity, flexibility and reusability of XML, and the type information (be it a XML Schema, Relax NG, the older DTD or just informal), provides isolation across customers and producers.
Simplicity is key: it is possible to quickly write a consumer or producer for this class of services in almost any language, including AJAX clients. And what has been missing is a simple, standard way to describe (WSDL is too complex) the services that can be used to advertise them and that can be used by different tools. WADL fills in this gap, and Marc just announced an Open Source project around this effort.
There are many opportunities for contributions; I personally would like to see tools for languages different than Java, and using annotations to further simplify the Map to Java. You could also help start cataloging more servicers available in the web; you do not even need to use XSD, WADL supports also Relax NG. And, if your site is a Web Services producer, I would encourage you to include a WADL description of your service.
Some people use the term REST to mean any typed XML over HTTP; the two are related but REST also implies some other architectural contraints, although WADL be very useful in implementing RESTful services. For more info, check older WADL articles, as well as Marc's blog.