erlang - how can I send a param into websock connection using cowboy -

in cowboy websocket example in toppage_handler.erl

    handle(req, state) ->       {echo, req2} = cowboy_req:qs_val(<<"echo">>, req),       {ok, req, state}. 

i want param echo following function

for example:

localhost:8080/?echo=123

in ws_handler.erl

    websocket_init(_transportname, req, _opts) ->          %%how can use echo(123) here?          erlang:start_timer(1000, self(), <<"hello!">>),          {ok, req, undefined_state}. 

a simple workaround use path bindings :

in routes :

dispatch = cowboy_router:compile([     %% {hostmatch, list({pathmatch, handler, opts})}     {'_', [{"/echo/:echo", my_handler, []}]} ]), 

then in code :

{echo, req2} = cowboy_req(echo,req) 

it's best in websocket_handle because able send response socket. in init, have carry in state, :

websocket_init(_transportname, req, _opts) ->     {echo, req2} = cowboy_req:binding(echo,req),     erlang:start_timer(1000, self(), <<"hello!">>),     {ok, req2, {echo}}.  websocket_handle(_frame, req, {echo}) ->     {reply, {text, echo}, req, state}. 

as websocket designed handle long term connections, use bindings support information channels, user ids, etc. not data in "echo" because want send multiple different texts echo without closing , reopen websocket connection each time change url.