I have for quite some time wanted to see self-describing information/functionality akin to WSDLs for JSON-based web services/APIs. There's something quite nice

I have for quite some time wanted to see self-describing information/functionality akin to WSDLs for JSON-based web services/APIs. There's something quite nice about being able to have a program intelligently build up knowledge of how to interact with an API, and be able to build a set of objects from a definition to facilitate that interaction. It's a serious weakness in non-XML APIs. Full disclosure: I particularly do not like XML-based web services, so please don't misread this as a cheap shot at JSON APIs. I prefer JSON, but programming against APIs would be so much nicer if there were a WSDL for JSON APIs.