Ajax

I would like to learn about Ajax push and pull concepts. If there is any tutorial or book, I'd appreciate any suggestions.

What is AJAX Push?

Ajax Push allows the application to incrementally update any part of the page at any time, for any group of clients.

What is pull and push technologies?

Pull technology is used anytime the transfer of information is initiated by a request sent from a client to a server. Push technology, on the other hand, is implemented any time a transfer of information is initiated by a server without waiting on a request from a client.

Why use ajax?

AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page. Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.

Here is a nice A Comparison of Push and Pull Techniques for AJAX for you.