Can somebody please let me know how i can add long polling and other fallback support for websocket using Jetty 9?
I generally recommend using something like CometD (http://www.cometd.org) which will be releasing version 3 fairly soon which will support Jetty 9. Another option would be to look at the Atmosphere project.
Using a messaging framework like these let you have the framework handle finding the best protocol to use, be it SPDY, Websocket, HTTP/1.1 or even polling HTTP/1.0....and they isolate you from future protocols like HTTP/2 which is coming (slowly) which is based on spdy. Using CometD once that protocol lands and becomes available get it for free, no changes needed in your app.