| By Mike Padilla |
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| December 5, 2007 10:30 AM EST |
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Ever since Jesse James Garrett coined the term AJAX to describe the collection of existing technologies that allow increased responsiveness and interactivity of webpages, its adoption has been embraced across the Web. But have designers and developers gone overboard? Is everything a nail to be pounded with the AJAX hammer? Some of the fundamental technologies that AJAX is based on, including HTML, CSS, and JavaScript, can sometimes offer simpler, more elegant solutions that are better suited to certain user experiences.
To optimally prescribe the use of AJAX, we need to understand the benefits and drawbacks, similarities and differences, and key interaction characteristics associated across the spectrum of static HTML to dynamic HTML to AJAX.
AJAX Ancestry
In the beginning, there were static webpages. Then along came dynamic HTML (DHTML), the combination of HTML, JavaScript and CSS. Webpages became more interactive and were able to change a small degree without requiring a page refresh. Yet the interaction was fundamentally constrained to the amount of data that could be reasonably pulled down to the client per page load. Finally, AJAX arrived and greatly increased the responsiveness and interactivity of webpages by asynchronously exchanging small streams of data with the server in the background in coordination with interactive DHTML.
Page level interaction was freed from the constraint of requiring a page reload to communicate with the server. But DHTML did not replace HTML and AJAX did not replace DHTML. Instead each technique represents a progressive collection of technologies that builds upon one another. More importantly, each technique, in of itself, with unique benefits and drawbacks, still offers suitable solutions for particular design problems.
Peeling the AJAX Onion
HTML is the core technology of the website presentation tier. As old as it is, it’s still the backbone of most everything that we see on the Web today. In of itself, HTML can be used to create static webpages that link to one another, automatically provide a page state model (easily bookmarked and shared, reside in the history object), are accessible, and are easily indexed by search engines. That’s all pretty powerful stuff that accomplishes most of what the Web is primarily used for – information retrieval.
Mike Padilla is a user experience manager at Vanguard. He has led front-end development efforts for such companies as Fleet Credit Cards, Mellon Private Asset Management, The Bank of New York, Radian Guaranty, and Bessemer Trust. Macromedia has featured his usability designs. He received a B.S. in mechanical engineering, focusing on ergonomics, from Cornell University.
Padilla is an ardent advocate of high-fidelity prototyping during requirements development. In his spare time, he designed and developed Protonotes, a free AJAX web service that allows project team members to discuss system functionality, design, and requirements directly on prototypes with "sticky notes".
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