Using websockets with rails, and also using node servers with rails.

1. Rails and Sockets

2. Websocket Rails Gem
https://github.com/websocket-rails/websocket-rails

3. Steps
● Add Gem “websocket-rails”
● bundle install
● rails g websocket_rails:install
● config.middleware.delete Rack::Lock
● rails server

4. B
Client
var dispatcher = new WebSocketRails('localhost:3000/websocket');
Initialize the socket
File: application.js

5. Bind for changes
channel = dispatcher.subscribe('posts');
channel.bind('new', function(data) {
console.log('a new post about '+data.title+'
arrived!');
});
File: application.js

6. Server
rails g scaffold posts title:string description:string
In some_action (create)
WebsocketRails[:posts].trigger 'new', latest_post
File: posts_controller create action

7. Events from clients

8. Event Router - Client
var success = function(res) { console.log("Created: " + res.post.title);
}
var failure = function(res) {
console.log("Failed to create post: " + res)
}
dispatcher.trigger(‘create_event', post, success, failure);
File: application.js

9. Event Router - Server
WebsocketRails::EventMap.describe do
# using a Hash to specify the target
subscribe :create_event, 'sockets#create_from_socket'
end
File: config/events.rb

10. class SocketsController < WebsocketRails::BaseController
def create_from_socket
post = Post.new message
if post.save
trigger_success post: post
else
trigger_failure post: post.errors
end
end
end
Event Router - Server
File: sockets_controller

11. ● sinatra-websocket
● webmachine-ruby
● faye-websocket
● tubesock
Few more!

12. Rails and Node
http://liamkaufman.com/blog/2013/02/27/adding-real-time-to-a-
restful-rails-app/

13. Basic Flow

14. Node and Redis
Prerequisites

15. Setting up Rails Server
gem 'redis'
gem 'socket.io-rails'
File: gemfile

16. Initializing Redis on Server
$redis = Redis.new(:host => 'localhost', :port=> 6379)
File: initializers/redis_init.rb (manually_created)

17. $redis.publish 'rt-change', @post.to_json
Publishing from rails to a channel
File: posts_controller.rb

18. Setting up Node Server
Listen and subscribe to changes in rt-change (rails)
channel
var io = require('socket.io').listen(5001),
redis = require('redis').createClient();
redis.subscribe('rt-change');
io.on('connection', function(soc){
console.log(soc.id);
});
});
File: app/<folder>/<file-name>.js

19. Setting up Node Server
Publishing changes to client channel
redis.on('message', function(channel, message){
io.sockets.emit('client-channel',JSON.parse(message));
});
File: app/<folder>/<file-name>.js

20. Setting up Rails Client
Include //= require socket.io in application.js
socket = io.connect("http://0.0.0.0:5001");
socket.on("client-channel", function(message){
alert(message);
});
File: application.js

21. Rails - rails s
Node - node <folder>/<file-name>.js
Start the servers
File: app/<folder>/<file-name>.js

22. redis_pub = require('redis').createClient();
redis_pub.publish('my_callback', JSON.parse(message));
Callback from node
File: app/<folder>/<file-name>.js

23. $redis.subscribe("my_callback") do |on|
on.message do |channel, message|
puts message.to_s
end
end
A task to listen on
callbacks from node
File: app/lib/tasks/<file-name>.rake

24. Load distribution.
Easy integration with APNS,MPNS and GCM services.
Also has queuing systems.
Advantages

25. Few ways to manage
node server
Forever - https://github.com/nodejitsu/forever
PM2 - https://github.com/Unitech/pm2

26. Questions?

27. https://github.com/shrikanthkr/wsrails
https://github.com/shrikanthkr/redis-socketio
Samples

28. Thank You!