Real-Time notification pop ups?

[mingalls]

I'm sorry to ask a vague question, but I can't find the answer to this anywhere. I have a site that involves users. What I would like to know is if there is a code or some type of programming that would notify a user of a different user's action. For example, USER A adds content to one section of my site, and USER B gets a notification "pop-up" I call it while he is looking at any other page on the site, without reloading the page, just popping up right when it happens. Things like, "USER A has just logged on". Any help would be GREATLY appreciated!

[Nile]

You might want to try ajax. Once you understand the basics, you can use Jquery Ajax to help you.

You would need a fall back for users that do not have javascript enabled.

[mingalls]

Would the AJAX actually be able to show something on another user's screen at the exact moment I do something on my screen? If we're on different pages of the site? That's the most important part. Thank you for your post to my question, EVERY bit helps me!!