This document introduces websocket-rails, a gem for building real-time web applications using websockets in Ruby on Rails. It allows asynchronous full-duplex communication by using websockets instead of traditional HTTP requests. The gem maps websocket events to controller actions, and controllers can then trigger events that are broadcast to clients. This enables features like pushing new data to only interested clients in real-time. Code examples demonstrate setting up websocket-rails, defining event mappings and controllers, and binding to events from the client-side.

1. Websocket on rails
Building realtime webapps

3. I'm a Java
Developer
who likes to
ride the
rails!

4. The future is now!

5. What's so great
about Websocket?

6. HTTP is half-duplex

7. Asynchronous full-duplex
communication
Websocket is asynchronous & full-duplex

8. So, a little less of this...

9. So instead of this...
Or this...

10. Or this...

11. You tell me... what's new?

12. Push

13. So, how to ride the rails with this?

14. Introducing websocket-rails
1. echo "gem 'thin'" >> Gemfile
2. echo "gem 'websocket-rails'" >> Gemfile
3. bundle install
4. rails g websocket_rails:install

16. Ruby
eventmachine

18. Map events to controller actions
WebsocketRails::EventMap.describe do
# You can use this file to map incoming events to controller
actions.
# One event can be mapped to any number of controller
actions. The
# actions will be executed in the order they were subscribed.
namespace :rsvp do
subscribe :new, :to => RsvpController, :with_method => :
rsvp
end
end

19. Use rails-like controllers
class RsvpController < WebsocketRails::BaseController
def initialize_session
# initialize application scoped variables here
@rsvp_yes_count = 0
end
def rsvp
@rsvp_yes_count += 1 if message
broadcast_message :new_rsvp, @rsvp_yes_count
end
end

20. Trigger and bind to events in the
client
$ ->
dispatcher = new WebSocketRails('localhost:3000/websocket')
dispatcher.on_open = (data) ->
console.log "Connection has been established: #{data}"
$('#rsvp_yes').bind 'click', (message) =>
dispatcher.trigger 'rsvp.new', true
dispatcher.bind 'new_rsvp', (rsvp_yes_count) =>
$('#rsvp_yes_count').html rsvp_yes_count

21. Broadcast
to anyone
out there,
or...

22. ...only push to whom is interested

23. Use complex messages and channels
(1)
class RsvpController < WebsocketRails::BaseController
...
def rsvp
@rsvp_yes_count += 1 if message[:attending]
rsvp = {
:yes => @rsvp_yes_count
}
WebsocketRails[:rsvp].trigger 'new', rsvp
end
end

24. Use complex messages and channels
(2)
$ ->
dispatcher = new WebSocketRails('localhost:3000/websocket')
$('#rsvp_yes').bind 'click', (message) =>
rsvp =
attending: true
dispatcher.trigger 'rsvp.new', rsvp
channel = dispatcher.subscribe 'rsvp'
channel.bind 'new', (rsvp) =>
$('#rsvp_yes_count').html rsvp.yes

25. Demo

26. References
Websocket spec
● http://dev.w3.org/html5/websockets/
Websocket-rails project page
● http://danknox.github.com/websocket-rails/
My project
● https://github.com/jeroenr/followup
Ruby eventmachine
● http://rubyeventmachine.com/