AJAX (Asynchronous JavaScript And XML) is the latest buzz

AJAX (Asynchronous JavaScript And XML) is the latest buzz word taking the world of web development by storm. Apart from its fancy name, it actually represents a technique for creating interactive web applications that are faster and smoother by using JavaScript to communicate with the server behind the scenes (“asynchronously”).

One difference between desktop and web applications is that unlike in the desktop environment, one often has to wait for an entire web page to load each time the user requests an operation. I'm sure we have all gotten slightly annoyed when having to wait for especially slow websites!

Technical details aside, JavaScript uses a method called XMLHttpRequest that enable us to communicate directly with the server, instead of loading another HTML page to get the information we need. Data retrieved in this way is commonly formatted using XML (eXtensible Markup Language).

The term AJAX itself was first coined Jesse James Garrett (founder of Adaptive Path, an information architecture and user experience firm) in February 2005, when he wanted a shorthand term to represent the suite of technologies he was proposing to a client. Although the term AJAX itself is new, the technologies behind the technique have been around for nearly a decade now, starting with Microsoft's initiatives in developing Remote Scripting.

Despite the numerous advantages that AJAX brings, in-terms of improving the speed and user friendliness of a web application, it also poses numerous challenges to web developers. One huge drawback of AJAX is that the dynamically created pages do not register themselves with the browser history engine, so "Back" button of the users' browser is rendered useless. In addition, AJAX relies on JavaScript heavily, but JavaScript implementation differently in the various browsers we have today, and care must be taken to ensure that the AJAX application is cross-platform compatible. AJAX also poses usability issues as users who have JavaScript disabled (a common security measure in many corporate environments) will be unable to use the application, unless a fallback is provided for these users.

If you want to get down and dirty with AJAX, here are a few good places to start off with. Please not however that AJAX can be confusing to someone with little web programming experience. So it is highly recommended that you are familiar with HTML and JavaScript before attempting these tutorials:

AJAX tutorial from TIZAG:

http://www.tizag.com/ajaxTutorial/

AJAX, what is it good for?

http://dhtmlnirvana.com/ajax/ajax_tutorial/