Introduction

Ajax is the current rising star in the web development field. Several popular company already started using Ajax, including: Google (Gmail, GMaps, GSuggest, GGroups), Amazon (A9.com), Flickr, and Orkut.

Ajax is not a new technology. It’s a new developing approach, based on the following existing technologies:

• XHTML and CSS for standard presentation,
• DOM (Document Object Model) for dynamic and interactive presentation,
• XML and XSLT for data exchange and manipulation, and
• XMLHttpRequest for asynchronius data retrieval

The foundation of Ajax is XMLHttpRequest object. It was first implemented by Microsoft on Internet Explorer 5 as an ActiveX object. Later, Mozilla engineers developed a compatible native version for Mozilla 1.0 (and Netscape 7), followed by Apple on their Safari 1.2 browser.

In short, the purpose of this XMLHttpRequest object is to handle data request asynchronously in the background for any web application who need to exchange and manipulate data on-the-fly without reloading the page. In traditional data processing, user submits the data through form, browser sends the data to the server, then server return the output through a new page, so browser need to load that new page in order to display the result to user.

To see what Ajax looks like, just login to your GMail account (if you don’t have one, get it free here ), and check your inbox. You’ll see a “Loading” message on the top right of the screen. Then the message disappear, and a list of your inbox message is displayed. All of them happen without reloading the page. Compare the process with Yahoo! Mail or HotMail. Google’s GMail used Ajax, and that’s what you get with Ajax implementation. Cool, huh? :))

On the next page, we will discuss more about XMLHttpRequest object.