WebSocket — the future AJAX PlatformWebSocket is a protocol providing full-duplex communications channels over a single TCP connection. Designed to be implemented in web browsers and web servers, it can also be used by any client or server application for fastest possible communication.
and therefore the most suitable platform for AJAX solutions.
Please read  and then:
- Wang, Salim, Moskovits: The Definitive Guide to HTML5 WebSocket (Apress, 2013).
- Comparison of WebSocket implementations
- WebSockets and how to use them
- More ...
See also Kaazing's JMS Software, a Cookbook for it, and an Echo Test Server.
Based on WebSocket are:
stw4141WSAJAXHTML — WebSocket . AJAX . HTML5 — News?
Plus + B G E + More
PHP and WebSockets
HTML5 WebSocket: A Quantum Leap in Scalability for the Web