async_sinatra_example_1.rb

require 'async_sinatra'

class App < Sinatra::Base
  register Sinatra::Async

  aget '/' do
    timed_out = false

    timeout = EM::Timer.new(7) do
      timed_out = true
      body { '{"state": "not_found"}' }
    end

    completion = lambda do |result|
      timeout.cancel

      body { result } unless timed_out
    end

    work = lambda do

      # do something here to calculate result

      result
    end

    EM.defer(work, completion)
  end
end