Reverse Ajax

Abstract:

The Problem. But what if you want to build a highly interactive
application that adds updates to your page as soon as someone half way
around the world updates theirs? What if you are in a CMS interface and
you go to check out some content and find you colleague in marketing
checked it out 2 minutes ago, but the page you are looking at hasn't
been updated since then? What if you are writing an article on Reverse
Ajax using Writely and your technical editor just updated the paragraph
you were going to work on? These are essentially monitoring and
multi-user applications.

The browser does the asking. The
problem is that web servers can't easily contact web browsers. For one
thing firewalls will get in the way, and even if they didn't, browsers
only listen for answers to questions they've asked. So how is the web
server to get the message through?

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