RESTful Services - WSDL Equivalent

Question

I have been reading about REST and SOAP, and understand why implementing REST can be beneficial over using a SOAP protocol. However, I still don't understand why there isn't the "WSDL" equivalent in the REST world. I have seen posts saying there is "no need" for the WSDL or that it would be redundant In the REST world, but I don't understand why. Isn't it always useful to programmatically bind to a definition and create proxy classes instead of manually coding? I don't mean to get into a philosophical debate, just looking for the reason there is no WSDL in REST, or why it is not needed. Thanks.

Answer 1

The Web Application Description Language (WADL) is basically the equivalent to WSDL for RESTful services but there's been an ongoing controversy whether something like this is needed at all.

Joe Gregorio has written a nice article about that topic which is worth a read.

Answer 2

WSDL describes service endpoints. REST clients should not be coupled to server endpoints (i.e. should not be aware of in URLs in advance). REST clients are coupled on the media-types that are transfered between the client and server.

It may make sense to auto generate classes on the client to wrap around the returned media-types. However, as soon as you start to create proxy classes around the service interactions you start to obscure the HTTP interactions and risk degenerating back towards a RPC model.