Gemfile

## Gemfile
source :gemcutter

gem 'goliath', :git => 'git://github.com/postrank-labs/goliath.git'
gem 'em-synchrony', :git => 'git://github.com/igrigorik/em-synchrony.git'

## index.html
<!DOCTYPE html>
<html>
<body>
  <h3>Hello SSE!</h3>
  <script>
    var source = new EventSource('/events');

    // new connection opened callback
    source.addEventListener('open', function(e) {
      console.log('connection opened');
    }, false);

    // subscribe to unnamed messages
    source.onmessage = function(e) {
      console.log(e);
      document.body.innerHTML += e.data + '<br />';
    };

    // listen for signup events
    source.addEventListener('signup', function(e) {
      console.log(e);
      document.body.innerHTML += e.data + '<br />';
    }, false);

    // connection closed callback
    source.addEventListener('error', function(e) {
      if (e.eventPhase == EventSource.CLOSED) {
        console.log('connection closed');
      }
    }, false);

  </script>
</body>
</html>

## Procfile
web: bundle exec ruby sse.rb -sv -e prod -p $PORT

## sse.rb
require 'goliath'

class SSE < Goliath::API
  use Rack::Static, :urls => ["/index.html"], :root => Goliath::Application.app_path("public")

  def response(env)
    EM.add_periodic_timer(1) { env.stream_send("data:hello ##{rand(100)}\n\n") }
    EM.add_periodic_timer(3) do
      env.stream_send(["event:signup", "data:signup event ##{rand(100)}\n\n"].join("\n"))
    end

    streaming_response(200, {'Content-Type' => 'text/event-stream'})
  end
end