event_stream.rb

require 'rack'                                                                  
require 'json'                                                                  
require 'torquebox-messaging'                                                   
                                                                                
class EventStream                                                               
  def self.call(env)                                                            
    path = Rack::Utils.unescape env["PATH_INFO"]                                
    [200, {                                                                     
      'Content-Type' => 'text/event-stream',                                    
      'X-Accel-Buffering' => 'no',                                              
    },                                                                          
    TopicStreamer.new(path)]
  end                                                                           
                                                                                
  class TopicStreamer
    def initialize(route)                                                       
      name = "/topics#{route}"                                                  
      TorqueBox::Messaging::Topic.start(name)                                   
      @topic = TorqueBox::Messaging::Topic.new(name)                            
    end                                                                         
    def each(&blk)                                                              
      blk.call("retry: 1000\n")                                                 
      while true                                                                
        msg = @topic.receive(:timeout => 20_000)                                
        blk.call(msg ? "data: #{msg.to_json}\n\n" : ":\n")
      end                                                                       
    end                                                                         
  end                                                                           
end