Although I have used AJAX my Comet (general word for technology allowing web server push) theory is very weak.
When using XHR object can you use multiple instances on the same connection (I imagine yes like websockets) and if you can how is this possible on one connection and one port, is it multiplexing?
How does XHR streaming work and could I have a very simple bit of AJAX code to see.
JSON explanation i.e. compared to XML and how has it anything to do with being an alternative to comet as I thought it was just like XML - a way to describe data?