Server Polling - Reverse AJAX

I am starting to feel a bit old or old-school. I know the concepts of AJAX but never had enough time (or project) to get my hands dirty doing AJAX. So I decided to make time and learn AJAX by doing.

I joined the 10-Week Free AJAX Programming (with Passion!) online course organized by Sang Shin from Sun Microsystems. This course is in its second week now and the homework was:

"... to write one or two paragraphs describing an "interesting" AJAX related technology/feature you find while you are playing with the online demos or while reading AJAX articles on the net"

I though that it would be good to share my point of view with you. So, here I go.

Title: Server Polling - Reverse Ajax)
URL: http://ajaxian.com/archives/reverse-ajax-with-dwr

Keeping the displayed information up-to-date was always difficult in web world. Before AJAX, one had to use JavaScript or META Refresh tag to get the page refreshed. This was quite annoying from the user experience point of view. However it was not as annoying as something that I experienced few days ago on one of the banks website (a bank in Australia). I was filling out the form and there were couple of select boxes on the page. I selected an option in the select box and moved onto next field just to realize that as I was typing, the page has been reloaded and all data entered past that select-box was gone and had to be re-typed again. Very, very annoying - and it's AJAX age already!

Server polling, in my humble opinion, is a great feature of AJAX. There is no need to refresh the whole page to obtain the required information. With AJAX, it is possible to:

• update the forms with information as the user moves through the form (e.g. country - state - city)
• get the feedback about a long server-side or transport process (e.g. progress bar showing the percentage of the uploading file)
• fake the push of the updated data from the server (think stock prices, weather, traffic info)

I am sure that I will come across more coolness when I start writing more and more Ajax code!