AJAX (maybe?) Question regarding Facebook

[DragonFire-N[R]]

Alright, so I recently toyed around with Facebook's chat feature, and to my complete amazement, messages are sent instantly from one person to another. I would have expected a delay, thinking maybe the chat loaded every five seconds to see if a new message appeared, but this was certainly not the case. I had two computers on right next to each other and I sent a message, and the other computer received it instantly. I even tested it over different networks and it was still instant.

 

I have never seen anything like it where data could be received as quickly as this. Typically what I would expect is the page to check for new messages every few seconds and display them if they exist. I honestly have no idea how to do this instantaneous programming so any insight would be very much helpful!

[RichardRotterdam]

It's because facebook chat is using a push technique as opposite to pulling data periodically. Try and lookup "Comet" or "ajax push" to find more info.