example of long polling using sinatra and jquery

longpoll.rb

require 'json'
require 'haml'
require 'sinatra'

get '/' do
  haml :view
end

get '/request' do
  content_type :json
  num = rand(6) + 1
  sleep(num)  # simulate work
  { :num => num }.to_json
end

__END__

@@view
!!!
%html
  %head
    %title longpoll test
    %script(type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js")
    :javascript
      var LongPoll = {
        ask: function() {
          $.ajax({
            url: '/request',
            success: function(data) {
              $('#test-box').append(data.num);
              LongPoll.ask();
            },
            timeout: 10000
          });
        }
      };
      $(document).ready(function() {
        LongPoll.ask();
      });
  %body
    %h3 test-box
    #test-box

This is not long polling, but short polling.