Question

I would like start a long poll request from javascript which is fine and i expect my ruby prog to stream multiple body sections to the javascript. Why doesn the following (pseudo)code work?

require 'rubygems'
require 'sinatra/async'
require 'eventmachine'
require 'thin'
require 'json'

    class Test < Sinatra:Base
      register Sinatra::Async

      aget '/process' do
        for c in 1..10
          body {
            { :data => [ "this is part #{c}" ] }.to_json
          end
        end
      end

      run!
    end

Maybe i misunderstood what long polling and async is supposed to do, but my expectation is that i get multiple bodies sent back to the client ? Do i need to use eventmachine or something?

thanks

Answer 1

require 'rubygems'
require 'sinatra/async'
require 'thin'
require 'json'

class Test < Sinatra::Base
  register Sinatra::Async

  class JSONStream
    include EventMachine::Deferrable

    def stream(object)
      @block.call object.to_json + "\n"
    end

    def each(&block)
      @block = block
    end
  end

  aget '/process' do
    puts 'ok'
    out = JSONStream.new
    body out
    EM.next_tick do
      c = 0
      timer = EM.add_periodic_timer(0.3) do
        c += 1
        out.stream :data => ["this is part #{c}"]
        if c == 100
          timer.cancel
          out.succeed
        end
      end
    end
  end

  run!
end

See also: http://confreaks.net/videos/564-scotlandruby2011-real-time-rack