AJAX - Asynchronous JavaScript + XML

Have you ever wondered how does google's gmail updates the new mail received without refreshing the web page or when you try Google Suggest, type in anything that interests you and magically the drop-down list is populated with suggestions! Same with Google Map, you pan/zoom, things happens without refreshing the web page.

Before I go any further I must mention that AJAX acronym was coined by Jesse James Garrett of Adaptive Path. This all became known to everyone once he published his blog and talked about it.

All this is possible with something called AJAX. Basically its asynchronous XML data transfer that happens between the javascript in that web page and backend server using HTTP GET/POST with pure XML data. All this is enabled by XMLHttpRequest object that IE provided. Its not yet standard JavaScript object but supported by all the major browser.

This is going to be a major shift in traditional web programming. My main interest is on the server side that handles the HTTP GET/POST and responds with HTTP header type text/xml and some XML data. This all happens with the web services, where instead of SOAP Binding you provide HTTP binding and that's it, the web services engine don't talk in terms of SOAP, it just talks plain XML over HTTP! Google and Amazon already expose their web services endpoints thru WSDL and also XML Schema.

How AJAX fits into J2EE, see java blueprints catalog.