Considering Ajax, Part 1: Cut through the hype

[Ronin]

Lately, interest in Ajax (Asynchronous JavaScript and XML) is high. Various Ajax applications provide a more interactive and rich client experience than traditional Web pages. Using Ajax, you can deploy new and innovative aggregation and presentation techniques in an unprecedented fashion. Inspired by Alex Bosworth's list of Ajax mistakes, Chris Laffra has compiled a set of discussion points for every developer to consider before using Ajax techniques for a Web site that he outlines in this two-part series. Some points are potential problem areas; most highlight Ajax's great potential.

The hottest topic these days on venture capital (VC) calendars and developer blogs is Ajax. Major ingredients of Ajax have been around for over a decade, so there really isn't much new to Ajax. However, the name Ajax,which stands for Asynchronous JavaScript and XML, is pretty new; it was introduced in 2005 by Jesse James Garrett of Adaptive Path. Leaning heavily on Dynamic HTML (DHTML), Ajax tries to avoid round trips to the server. When an Ajax application updates some information, it does not replace the entire page in the Web browser. Instead, JavaScript code sends an XML request to the server, and at some later point replaces a selected subset of the DOM to update the current page.

Before the advent of Ajax, DHTML was usually restricted to the implementation of menus or tables of contents, limited forms of animation, and tabbed folders. To make a DHTML Web site portable between various browsers is difficult. This created a market for companies like Bindowsâ„¢ that offer comprehensive abstractions for developing interesting rich clients; the online version of the Eclipseâ„¢ FAQs is a good example (see Resources for a link to this and other sites.)

Arguably, the most influential Ajax application so far is Googleâ„¢ Maps. It has generated a whole new computer science discipline. (A search at Google for "Hacking Google Maps" returns over 2 million hits; go figure.) Nice examples of Google Map hacks include transparent maps, Bus Monster, and HousingMaps.com. Personally, I am most intrigued by Google's personalization features, where you can use DHTML to drag and position existing and new content on a personalized home page. There is an inkling of custom mashup as users can perform any Google search and add a selected host to their home page.


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