title: State-of-the-art HTTP push: jQuery, cometd?
body: <p>There are various old questions in the stackoverflow archives, like <a href="https://stackoverflow.com/questions/136012/comet-and-jquery">this one</a>, which talk about cometd and friends. But I wanted to ask what the best technology is these days. Is it cometd?</p>
  
  <p>I want to implement basic server-side push using ruby, preferably rails (though eventmachine or similar is possible). What is the best way to do this? For the purposes of this question, imagine I'm building a browser-based chat service. I use jQuery.</p>
  
  <p>What do people use these days? Anyone know what kind of technology Facebook uses to push notifications to browsers? Priorities (in order) are:</p>
  
  <ol>
  <li>Ease of integrating with jQuery (or pure javascript) + Ruby-based server.</li>
  <li>Simplicity/elegance.</li>
  <li>Some degree of cross-browser compatibility (though not necessarily as old as IE 6).</li>
  <li>Performance.</li>
  </ol>