youpy/server_push_with_xhr.rb

## server_push_with_xhr.rb
require 'rubygems'
require 'sinatra'

# doesn't work on thin and webrick
set :server, 'mongrel'

get '/' do
  <<HTML
<html>
  <head>
    <title>Server Push</title>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
    <script src="/js/server_push.js"></script>
  </head>
  <body>
    <h1>Server Push</h1>
    <div id="content"></div>
  </body>
</html>
HTML
end

get '/js/server_push.js' do
  <<JS
$(function() {
  var xhr = new XMLHttpRequest();
  xhr.multipart = true;
  xhr.onreadystatechange = function() {
    // 1->2->3->4->1->...
    $('#content').append("<p>readyState: " + xhr.readyState + "</p>");

    if(xhr.readyState == 4) {
      $('#content').append(xhr.responseText);
    }
  };
  xhr.open("GET", "/push");
  xhr.send(null);
});
JS
end

get '/push' do
  boundary = 'ThisRandomString'
  response['Content-Type'] = 'multipart/x-mixed-replace;boundary=' + boundary

  PushResponse.new(boundary, 'text/plain', 3) do
    "<p>#{rand.to_s}</p>"
  end
end

class PushResponse
  def initialize(boundary, content_type, interval, &block)
    @boundary = boundary
    @content_type = content_type
    @interval = interval
    @block = block
  end

  def each
    yield "--#{@boundary}\n"

    loop do
      yield "Content-Type: #{@content_type}\n\n" + @block.call + "\n--#{@boundary}\n"
      sleep @interval
    end
  end
end
	require 'rubygems'
	require 'sinatra'

	# doesn't work on thin and webrick
	set :server, 'mongrel'

	get '/' do
	<<HTML
	<html>
	<head>
	<title>Server Push</title>
	<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
	<script src="/js/server_push.js"></script>
	</head>
	<body>
	<h1>Server Push</h1>
	<div id="content"></div>
	</body>
	</html>
	HTML
	end

	get '/js/server_push.js' do
	<<JS
	$(function() {
	var xhr = new XMLHttpRequest();
	xhr.multipart = true;
	xhr.onreadystatechange = function() {
	// 1->2->3->4->1->...
	$('#content').append("<p>readyState: " + xhr.readyState + "</p>");

	if(xhr.readyState == 4) {
	$('#content').append(xhr.responseText);
	}
	};
	xhr.open("GET", "/push");
	xhr.send(null);
	});
	JS
	end

	get '/push' do
	boundary = 'ThisRandomString'
	response['Content-Type'] = 'multipart/x-mixed-replace;boundary=' + boundary

	PushResponse.new(boundary, 'text/plain', 3) do
	"<p>#{rand.to_s}</p>"
	end
	end

	class PushResponse
	def initialize(boundary, content_type, interval, &block)
	@boundary = boundary
	@content_type = content_type
	@interval = interval
	@block = block
	end

	def each
	yield "--#{@boundary}\n"

	loop do
	yield "Content-Type: #{@content_type}\n\n" + @block.call + "\n--#{@boundary}\n"
	sleep @interval
	end
	end
	end