near-real-time

I'm about to develop a website that has near real time chat. I know that it can be implemented using xmpp or websocket protocols. I know also that the xmpp protocol has been developed in 1999 , and I guess it should be mature nowadays .On the other hand , the websocket protocol has been developed in 2011. What was the need for websocket if xmpp was good in handling real time conversations? What are the major differences between the 2 protocols? And when should I choose one of them over the other? The short answer is 'both'. XMPP is a set of application protocol for doing real-time chat (and