At the Forge - Beginning Ajax
However, we also see that there are security and efficiency problems with this approach. A better technique would be to send only the requested user name in the Ajax call and get a simple yes or no answer from the server, indicating whether the user name had been taken already. Next month, we will do just that, using an Ajax POST query instead of our GET query from this month, and replacing usernames.txt with a server-side program that works in conjunction with our Ajax call.
There has been an explosion of books and articles about Ajax programming in the last year, and I am slowly making my way through many of them. Two of the best that I've read are both published by O'Reilly. Head Rush Ajax is aimed at beginners and teaches the introductory material in a fun, effective way. Ajax Design Patterns, which I mentioned earlier in this article, is probably my favorite Ajax book so far (despite its design and editing, which aren't up to the usual O'Reilly standards). This latter book is a good introduction to the subject for experienced Web developers.
The Ajaxian.com Web site has a large number of links, tutorials and articles having to do with Ajax development on a variety of different platforms. If you're interested in Ajax development, it's worth keeping this site in your RSS reader or bookmarks.
Reuven M. Lerner, a longtime Web/database consultant, is a PhD candidate in Learning Sciences at Northwestern University in Evanston, Illinois. He currently lives with his wife and three children in Skokie, Illinois. You can read his Weblog at altneuland.lerner.co.il.