AJAX Web Programming, Part I

AJAX (Asynchronous JavaScript And XML) is a technology which can be used to improve the performance of Web applications. AJAX is currently a very trendy technology — by that I mean there are lots of new AJAX books, AJAX conferences, AJAX magazines articles, and so on. Technology is subject to trends just like anything else is. AJAX is not a programming language, it is a technique that uses existing languages in a new way. Before I explain how AJAX works, let me explain the problem that AJAX solves. Suppose you are at a Web page which displays maps, such as mapquest.com for example, and you click on a "North" icon to indicate you want to see the area to the north of the map section being currently displayed. Traditional (non-AJAX) Web technology would send an HTTP request to the mapquest.com Web server, then the server would find the map image you are requesting, then return that image to you, where your Internet Explorer Web browser would render the image. All of this would take quite some time (perhaps a second or two), which results in your Web page blanking out for a moment. AJAX is a way to solve this performance problem. Using a well-designed AJAX Web application, if you clicked on the "North" icon, you would get a very quick and smooth response to the next image. I’ll explain some of the details next time.

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