[erlang-questions] Push a message to cowboy websockets

[Barco You]

Hi Magnus,

Thank you very much!

Then, if broadcasting to all other clients except self, how to do it with
gproc?

Regards,
Barco

On Sat, Apr 7, 2012 at 10:02 PM, Magnus Klaar <magnus.klaar@REDACTED>wrote:

> Hi!
>
> This is the line where the crash is occuring at:  {reply, {text,
> <<Msg>>}, Req, State, hibernate}. The last message in was: {<0.113.0>,
> {websocket_handler, "broadcast"},<<"hello server!">>} Where Msg is bound to
> the <<"hello server!">> term in the message. The <<Msg>> expression
> attempts to pack this binary as a one-byte value which will not work.
> Remove the <<>>-s around Msg and you should be good to go. I also don't see
> why you have defined the ?BC macro/constant as a string, an atom would
> suffice.
>
> TLDR; replace {reply, {text, <<Msg>>}, Req, State, hibernate}.
> with  {reply, {text, Msg}, Req, State, hibernate}.
>
> MVH Magnus
>
> On Sat, Apr 7, 2012 at 3:50 PM, Barco You <barcojie@REDACTED> wrote:
>
>> Hi AD,
>>
>> I also tried to implement a websocket broadcast as you did in this mail.
>> but I got crash in websocket_info as following. Could you please show me
>> your complete code? thanks!
>>
>> my code is:
>>
>> websocket_init(_Any, Req, []) ->
>>     gproc:reg({p, l,{?MODULE, ?BC}}),
>>     Req2 = cowboy_http_req:compact(Req),
>>     {ok, Req2, undefined, hibernate}.
>>
>> websocket_handle({text, Msg}, Req, State) ->
>>     broadcast(Msg),
>>     {reply, {text, << "You said: ", Msg/binary >>}, Req, State,
>> hibernate};
>> websocket_handle(_Any, Req, State) ->
>>     {ok, Req, State}.
>>
>> websocket_info({_Pid, {_Module, ?BC}, Msg}, Req, State) ->
>>
>>     {reply, {text, <<Msg>>}, Req, State, hibernate}.
>>
>> broadcast(Msg) ->
>>     gproc:send({p, l, {?MODULE, ?BC}}, {self(), {?MODULE, ?BC}, Msg}).
>>
>>
>>
>> ** Handler websocket_handler terminating in websocket_info/3
>>
>>    for the reason error:badarg
>> ** Message was {<0.113.0>,{websocket_handler,
>> "broadcast"},<<"hello server!">>}
>> ** Options were []
>> ** Handler state was undefined
>> ** Request was [{socket,#Port<0.940>},
>>                 {transport,cowboy_tcp_transport},
>>                 {connection,keepalive},
>>                 {pid,<0.113.0>},
>>                 {method,'GET'},
>>                 {version,{1,1}},
>>                 {peer,undefined},
>>                 {host,undefined},
>>                 {host_info,undefined},
>>                 {raw_host,<<"localhost">>},
>>                 {port,80},
>>                 {path,undefined},
>>                 {path_info,undefined},
>>                 {raw_path,<<"/websocket">>},
>>                 {qs_vals,undefined},
>>                 {raw_qs,<<>>},
>>                 {bindings,undefined},
>>                 {headers,[]},
>>                 {p_headers,[]},
>>                 {cookies,[]},
>>                 {meta,[{websocket_version,13}]},
>>                 {body_state,waiting},
>>                 {buffer,<<>>},
>>                 {resp_state,done},
>>                 {resp_headers,[]},
>>                 {resp_body,<<>>},
>>                 {urldecode,{#Fun<cowboy_http.urldecode.2>,crash}}]
>> ** Stacktrace: [{websocket_handler,websocket_info,3,
>>                     [{file,"src/websocket_handler.erl"},{line,39}]},
>>                 {cowboy_http_websocket,handler_call,7,
>>                     [{file,"src/cowboy_http_websocket.erl"},{line,389}]}]
>>
>>
>
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