What Is AJAX?

There have been quite a few complaints about the name "Ajax" being applied to a Web tool, not the least of which point out that many people grew up with bathroom cleanser with the same name. For the more literate, it is also the name of the second greatest Greek warrior in The Iliad (Achilles being number one, of course) and the only one who fought without direct assistance from the gods. So how did this venerable name get attached to something that helps net surfers?

On the serious side, Ajax got its name the way a lot of techie things do, as an acronym for a suite of technologies used together. Just as "LAMP" is an abbreviation for Linux, Apache, MySQL and PHP, Ajax stands for Asynchronous JavaScript And XML, although it actually contains a few extras. Here are the components and a brief description of their functions:

HTML and CSS, which are used to present information graphically (copy, images, etc.);

JavaScript, for dynamic interactivity with the information that is presented; and

XML, XSLT and the oddly named "XMLHttpRequest" object, for manipulating data asynchronously with the Web server, which means that processes proceed independently, "in the background," while others can start before the asynchronous process finishes.

Exceeding the sum of the parts

The first question that presents itself is, Why bother with creating Ajax when HTML, CSS, JavaScript and the rest have been around since Web Day One (well, almost). The difference is in those "few extras" mentioned previously, specifically the XML. That particular acronym stands for eXtensible Markup Language, and it's the extensibility (expandability, customizability) that makes Ajax a Web tool of mythological proportions to its fans. The major, "flavor-changing" ingredient is XML, an environment that allows consistent tagging and identification of information buried in a Web site's pages and hierarchies.

Within that environment, XSLT is essentially a version or variant of XML that updates, manipulates and/or transforms XML documents via database-type queries - and does so "in place." The final piece of the puzzle, XMLHttpRequestor, is an application programming interfaces (API) set that allows Web applications to use the standard, garden-variety HTTP protocol for data transfer with a Web server. The various pieces work together, enabling JavaScript scripts (can we just agree to say, "JavaScript's"?) to request and receive data from the server without loading or reloading pages.

How it works

If you ever had the feeling that there was some unseen, unplanned browser-and-server interactivity taking place just out of sight, on every page you visit - well, you were right. Ajax also makes possible a whole lot of things that you do notice, too, such as the Google Maps views that drag, pan, zoom and swoop. Ajax's nuanced abilities also show up in Gmail's use of self-contained, swift table sorting. For a serious Web developer, Ajax is a must.

When you are putting it all together on the Web, the Ajax advantage comes down to its flexibility and ability to offer you shortcuts that don't shortchange. Users get that "rich" and "personalized" experience that they want, because Ajax functionality - in the form of special "gadgets" and "widgets" and, of course, the invisible helpers - means immediacy and relevance for Web users. Since graphical and textual updates do not have to cost the user time in page loads and reloads, the entire experience is smoother and more accelerated.

Benefits of Ajax

For serious Internet users, a consistent, ongoing chain of events that save users a second or two each time add up to a lot of hours over the course of a month, not to mention a year or two. The most important things to users, of course, are speed, usefulness and predictability - they want things quickly, they want things that they really need and they want to know that they can keep getting them whenever they want. For all kinds of companies with all kinds of Web sites, Ajax and other tools allow them to satisfy their visitors' needs for up-to-the-second information that is delivered seamlessly.

It's hard to recall, but the Internet "era" began when a graphical user interface, or GUI, was added to what was previously a text-based "online bulletin board." The World Wide Web, in fact, is technically a "layer" of the Internet. In fact, many of the first Web destinations were simply old bulletin board systems with some pictures and color added. Real-time page updates without reloading? Instant information that is always current? No way, not then, and not until some intervening technological advances made possible such Web warriors as Ajax.