Erlang socket.io server with supervisor - http

Question

I'm currently trying to create a simple chat server with socket.io-erlang. I just started learning Erlang so I have a few problems adapting their demo so it works with modules. Hope you can help me, here's what I have so far. It shouldn't have any features yet, this time I only want to make it work (I get a few crash reports after starting it, you can read them if you want).
App
-module(echat_app).
-behaviour(application).
-export([start/2, stop/1]).
start(_StartType, _StartArgs) ->
echat_sup:start_link().
stop(_State) ->
ok.
Supervisor
-module(echat_sup).
-behaviour(supervisor).
-export([start_link/0]).
-export([init/1]).
-define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}).
start_link() ->
supervisor:start_link({local, ?MODULE}, ?MODULE, []).
init([]) ->
application:start(sasl),
application:start(gproc),
application:start(misultin),
application:start(socketio),
{ok, Pid} = socketio_listener:start([{http_port, 7878}, {default_http_handler,echat_http_handler}]),
EventManager = socketio_listener:event_manager(Pid),
ok = gen_event:add_handler(EventManager, echat_socketio_handler,[]),
receive _ ->
io:format("sub received something"),
{ok, {
{one_for_one, 5, 10},
[]
}}
end.
Socket.IO Event Handler
-module(echat_socketio_handler).
-behaviour(gen_event).
-include_lib("socketio/include/socketio.hrl").
-export([init/1, handle_event/2, handle_call/2, handle_info/2, terminate/2, code_change/3]).
init([]) ->
{ok, undefined}.
handle_event({client, Pid}, State) ->
io:format("Connected: ~p~n",[Pid]),
EventManager = socketio_client:event_manager(Pid),
ok = gen_event:add_handler(EventManager, ?MODULE,[]),
{ok, State};
handle_event({disconnect, Pid}, State) ->
io:format("Disconnected: ~p~n",[Pid]),
{ok, State};
handle_event({message, Client, Msg=#msg{content=Content}}, State) ->
io:format("Got a message: ~p from ~p~n",[Msg, Client]),
socketio_client:send(Client, #msg{ content = "hello!" }),
socketio_client:send(Client, #msg{ content = [{<<"echo">>, Content}], json = true}),
{ok, State};
handle_event(_E, State) ->
{ok, State}.
handle_call(_, State) ->
{reply, ok, State}.
handle_info(_, State) ->
{ok, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
HTTP Request Handler
-module(echat_http_handler).
-export([handle_request/3]).
handle_request(_Method, _Path, Req) ->
Req:respond(200).

Answer 1

just a few things, no a specific answer to your question.
First, in general you start the dependencies before starting your app, rather than on the init of some supervisor.
Regarding the errors:
{error,{{noproc,{gen_server,call,
[socketio_listener_sup_sup,
{start_child,[[{http_port,7878},
{default_http_handler,echat_http_handler}]]},
infinity]}},
{echat_app,start,[normal,[]]}}}
This is the first one, it means that the code tried to call a gen_server named 'socketio_listener_sup_sup' , but that process did not exist. Given the name of it, I guess that is something that should be started by the socket.io-erlang application itself, so maybe it is not starting correctly for some reason. You can check that easily by checking the results:
ok = application:start(sasl),
ok = application:start(gproc),
ok = application:start(misultin),
ok = application:start(socketio),