Phoenix-like channels in Rails, adapted from: http://www.chrismccord.com/blog/2014/05/06/how-to-build-an-elixir-chat-app-with-phoenix/

chat_channel.rb

class ChatChannel < ActionChannel::Base
  # join is triggered on user connect
  def join(channel, message)
    puts "JOIN #{channel}"

    # reply messages are sent only to the user invoking the action
    reply "user:welcome", salute: "Welcome to the channel #{message['username']}!!!"

    # broadcast messages are sent to all the users connected to the channel
    broadcast "user:entered", username: message["username"]
  end

  def new_message(message)
    broadcast "new:message", content: message["content"], username: messages["username"]
  end

  # leave is triggered on user disconnect, by default we can provide a no-op method 
  # and allow to users to override it
  def leave(channel, message)
    broadcast "user:left", username: message["username"]
  end
end

# Broadcast an outgoing message to this channel from a controller/model:
# ChatChannel.broadcast "new:message", content: "Hello from Rails controller", username: "ChanServer"

example.js

var socket = new ActionChannel("ws://" + location.host + "/ws");
var $messages = $("#messages");
var $messageInput = $("#message-input");
var $usernameInput = $("#username");

socket.join("chat", {}, function(chan){

  chan.on("user:entered", function(message){
    $messages.append("<br/>[" + message.username + "] entered")
  });

  chan.on("new:message", function(msg){
    $messages.append("<br/>[" + msg.username + "] " + msg.content)
  });

  $messageInput.off("keypress").on("keypress", function(e){
    if(e.keyCode == 13){
      chan.send("new:message", {
        content: $messageInput.val(),
        username: $usernameInput.val()
      });
      $messageInput.val("");
    }
  });
});

routes.rb

ChatApp::Application.routes.draw do
  socket "/ws" do
    channel "chat"
  end
end