gistfile1.rb

class My::Channel < EM::Channel
  attr_accessor :watcher, :logger
  def self.create!
    channel = new
    channel.logger = Logger.new 'sinatra.log'
    channel.watcher
    channel
  end

  def watcher
    @watcher ||= fork do
      redis = Redis.new
      redis.subscribe("foobar") do |on|
        on.message do |channel, message|
          self.logger.info message
          self.push "asdfasf"
          My::FakeWebSocket.settings.sockets.each do |s|
            self.logger.info "socket notified"
            s.send message
          end
        end
      end
    end
  end
end

gistfile2.rb

  set :channel, My::Channel.create!
  get '/' do
    request.websocket do |ws|
      ws.onopen do
        settings.sockets << ws
        subscriber_id = settings.channel.subscribe do |json|
          LOGGER.info "the channel spoke"
          LOGGER.info json
          ws.send json
        end
        settings.subscriptions << subscriber_id
      end
      ws.onclose do
        warn("closing websocket")
        settings.sockets.delete ws
      end
    end
  end