cowboy_sub_protocol =================== The `cowboy_sub_protocol` behaviour defines the interface used by modules that implement a protocol on top of HTTP. Types ----- None. Callbacks --------- ### upgrade(Req, Env, Handler, Opts) -> {ok, Req, Env} | {suspend, Module, Function, Args} | {halt, Req} | {error, StatusCode, Req} > Types: > * Req = cowboy_req:req() > * Env = env() > * Handler = module() > * Opts = any() > * Module = module() > * Function = atom() > * Args = [any()] > * StatusCode = cowboy:http_status() > > Upgrade the protocol. > > Please refer to the `cowboy_middleware` manual for a > description of the return values.