CODEWITHSUNDEEP
httperlangsocket.iogen-event
Luis
Luis

Reputation: 211

Erlang socket.io server with supervisor

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).

Upvotes: 0

Views: 1097

Answers (1)

ppolv
ppolv

Reputation: 1319

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),

Upvotes: 1

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