Realtime Markdown preview with websocket

Gemfile

@@ -89,3 +89,4 @@ gem 'haml-rails'
 # for extension font
 gem 'font-awesome-sass'
 
+gem "websocket-rails"

Gemfile.lock

@@ -59,12 +59,19 @@ GEM
     coffee-script-source (1.9.1.1)
     columnize (0.9.0)
     crass (1.0.2)
+    daemons (1.2.3)
     debug_inspector (0.0.2)
+    em-synchrony (1.0.4)
+      eventmachine (>= 1.0.0.beta.1)
     erubis (2.7.0)
     escape_utils (1.1.0)
+    eventmachine (1.0.7)
     execjs (2.5.2)
     faraday (0.9.1)
       multipart-post (>= 1.2, < 3)
+    faye-websocket (0.10.0)
+      eventmachine (>= 0.12.0)
+      websocket-driver (>= 0.5.1)
     font-awesome-sass (4.3.2.1)
       sass (~> 3.2)
     gemoji (2.1.0)
@@ -84,6 +91,7 @@ GEM
       html2haml (>= 1.0.1)
       railties (>= 4.0.1)
     hashie (3.4.2)
+    hiredis (0.6.0)
     html-pipeline (1.11.0)
       activesupport (>= 2)
       nokogiri (~> 1.4)
@@ -173,6 +181,9 @@ GEM
       thor (>= 0.18.1, < 2.0)
     rake (10.4.2)
     rdoc (4.2.0)
+    redis (3.2.1)
+    redis-objects (1.2.0)
+      redis (>= 3.0.2)
     rinku (1.7.3)
     ruby_parser (3.7.0)
       sexp_processor (~> 4.1)
@@ -204,6 +215,10 @@ GEM
       activesupport (>= 3.0)
       sprockets (>= 2.8, < 4.0)
     sqlite3 (1.3.10)
+    thin (1.6.3)
+      daemons (~> 1.0, >= 1.0.9)
+      eventmachine (~> 1.0)
+      rack (~> 1.0)
     thor (0.19.1)
     thread_safe (0.3.5)
     tilt (1.4.1)
@@ -217,6 +232,18 @@ GEM
       binding_of_caller (>= 0.7.2)
       railties (>= 4.0)
       sprockets-rails (>= 2.0, < 4.0)
+    websocket-driver (0.6.2)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.2)
+    websocket-rails (0.7.0)
+      em-synchrony
+      faye-websocket
+      hiredis
+      rack
+      rails
+      redis
+      redis-objects
+      thin
     yajl-ruby (1.2.1)
 
 PLATFORMS
@@ -250,6 +277,7 @@ DEPENDENCIES
   sqlite3
   uglifier (>= 1.3.0)
   web-console (~> 2.0)
+  websocket-rails
 
 BUNDLED WITH
    1.10.4

app/assets/javascripts/application.js

@@ -15,3 +15,4 @@
 //= require_tree .
 //= require bootstrap-sprockets
 //= require jquery-textcomplete
+//= require websocket_rails/main

app/assets/javascripts/minutes.coffee

@@ -460,4 +460,9 @@ ready = ->
     else
       alert "No valid range is specified."
 
+  # Receiver
+  receiver = new WebSocketRails(location.host + '/websocket')
+  receiver.bind 'convert_markdown', (data) ->
+    $("#realtime-preview").html(data)
+
 $(document).ready(ready)

app/controllers/jay_markdown_controller.rb

@@ -0,0 +1,10 @@
+require "markdown_converter"
+
+class JayMarkdownController < WebsocketRails::BaseController
+
+  def convert
+    markdown = message()
+    html = ::JayFlavoredMarkdownConverter.new(markdown).content
+    broadcast_message(:convert_markdown, html)
+  end
+end

app/controllers/minutes_controller.rb

@@ -76,6 +76,9 @@ def destroy
     end
   end
 
+  def realtime_preview
+  end
+
   # for ajax search
   def search_by_tag
     unless tag = Tag.find_by(name: params[:tag_name])

app/views/minutes/realtime_preview.html.haml

@@ -0,0 +1,2 @@
+%h1 Realtime Preview
+.markdown-body#realtime-preview

config/environments/development.rb

@@ -38,4 +38,7 @@
 
   # Raises error for missing translations
   # config.action_view.raise_on_missing_translations = true
+
+  # For websocket-rails
+  config.middleware.delete Rack::Lock
 end

config/events.rb

@@ -0,0 +1,16 @@
+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.
+  #
+  # Uncomment and edit the next line to handle the client connected event:
+  #   subscribe :client_connected, :to => Controller, :with_method => :method_name
+  #
+  # Here is an example of mapping namespaced events:
+  #   namespace :product do
+  #     subscribe :new, :to => ProductController, :with_method => :new_product
+  #   end
+  # The above will handle an event triggered on the client like `product.new`.
+
+  subscribe :convert_markdown, :to => JayMarkdownController, :with_method => :convert
+end

config/initializers/websocket_rails.rb

@@ -0,0 +1,63 @@
+WebsocketRails.setup do |config|
+
+  # Uncomment to override the default log level. The log level can be
+  # any of the standard Logger log levels. By default it will mirror the
+  # current Rails environment log level.
+  # config.log_level = :debug
+
+  # Uncomment to change the default log file path.
+  # config.log_path = "#{Rails.root}/log/websocket_rails.log"
+
+  # Set to true if you wish to log the internal websocket_rails events
+  # such as the keepalive `websocket_rails.ping` event.
+  # config.log_internal_events = false
+
+  # Change to true to enable standalone server mode
+  # Start the standalone server with rake websocket_rails:start_server
+  # * Requires Redis
+  config.standalone = false
+
+  # Change to true to enable channel synchronization between
+  # multiple server instances.
+  # * Requires Redis.
+  config.synchronize = false
+
+  # Prevent Thin from daemonizing (default is true)
+  # config.daemonize = false
+
+  # Uncomment and edit to point to a different redis instance.
+  # Will not be used unless standalone or synchronization mode
+  # is enabled.
+  # config.redis_options = {:host => 'localhost', :port => '6379'}
+
+  # By default, all subscribers in to a channel will be removed
+  # when that channel is made private. If you don't wish active
+  # subscribers to be removed from a previously public channel
+  # when making it private, set the following to true.
+  # config.keep_subscribers_when_private = false
+
+  # Set to true if you wish to broadcast channel subscriber_join and
+  # subscriber_part events. All subscribers of a channel will be
+  # notified when other clients join and part the channel. If you are
+  # using the UserManager, the current_user object will be sent along
+  # with the event.
+  # config.broadcast_subscriber_events = true
+
+  # Used as the key for the WebsocketRails.users Hash. This method
+  # will be called on the `current_user` object in your controller
+  # if one exists. If `current_user` does not exist or does not
+  # respond to the identifier, the key will default to `connection.id`
+  # config.user_identifier = :id
+
+  # Uncomment and change this option to override the class associated
+  # with your `current_user` object. This class will be used when
+  # synchronization is enabled and you trigger events from background
+  # jobs using the WebsocketRails.users UserManager.
+  # config.user_class = User
+
+  # Supporting HTTP streaming on Internet Explorer versions 8 & 9
+  # requires CORS to be enabled for GET "/websocket" request.
+  # List here the origin domains allowed to perform the request.
+  # config.allowed_origins = ['http://localhost:3000']
+
+end

config/routes.rb

@@ -7,6 +7,7 @@
   get "/sessions/logout", to: "sessions#logout"
 
   post "/minutes/preview", to: "minutes#preview"
+  get "/minutes/realtime_preview", to: "minutes#realtime_preview"
   get "/minutes/search_by_tag", to: "minutes#search_by_tag"
 
   resources :minutes