This is something I am looking for as well. In my case I'd like to integrate a REST API with a Push Notifications API in a unified API specification.
Today I have resorted to using JSON schemas/hyperschemas with custom templating using the Heroku's prmd tool. Works ok but has the drawback that it relies on my custom made templates...
Does anyone know of any API specs written for websocket APIs?
I am working on creating a websocket API and would like to at least look at a few other examples.