title: What way of client should I choose for Comet chat?
body: <p>I am going to implement a Comet chat. It is easy to make a choice for the server side but for the client side--I am really confused: long polling, callback polling, hidden iframe, http streaming, persistent http connection....</p>
  
  <p>I don't know much about the conceptions, and who can help me to make it more clear? I just want to choose the best way to implement a Comet chat client~</p>