Michael Morrison [Michael Morrison] - Negus Live Linux Series Ajax Construction Kit: Building Plug-and-Play Ajax Applications

In lieu of the rapid ascent of Ajax, it is worth putting things into perspective as we chart a path into the future. One thing for certain is that many of us in the tech industry still have not learned our lesson from the dot-com bubble bursting of the late 90s. The term irrational exuberance has been used to describe the mentality that lead to unchecked rises in tech stocks during that period. A big part of the problem had to do with people latching on to the next big idea as if it was going to change the world as we know it. Of course the Internet as a whole has changed the world a fair amount, but many of us have a tendency to hype each new advance as if it alone holds the promise of unimaginable progress, efficiency, riches, etc. Ajax is one of these new advances.

When observed with a bit more perspective, it becomes apparent that Ajax is but one advance in the evolution of the Web. Im not attempting to understate the significance of the advance, but I am cautioning that we all shouldnt get carried away in the excitement of the newness. Ajax indeed offers the promise of a more responsive and ultimately more usable Web, and that is worthy of some excitement. But at the same time, lets not forget that it solves a very specific problem that isnt necessarily an issue with every Web application. Ajax is not a magic bullet that you fire at every Web page you develop.

As we venture into the uncharted future of the Web plus Ajax, the degree to which we restrain the usage of Ajax may ultimately play a critical role in Ajaxs continued success. This has to do with a variety of reasons, one of which is the fact that Ajax can actually put more of a workload on servers despite the fact that less information is typically being transferred. Sure, youve eliminated an entire page of data being sent with each request, but youve opted to fire off a couple dozen requests instead of just one. Depending on the specific server configuration, multiple small requests can potentially present more of a bottleneck than a single large request.

All this is to say that you should approach future Web projects knowing that Ajax is an incredibly handy tool, but its ultimately still just a tool. The old saying that to a hammer every problem looks like a nail certainly applies here. Just because you have the knowledge and code to inject Ajax into everything you do doesnt necessarily make it right. At the same time, even the smallest properly structured Ajax application can be incredibly compelling and dramatically improve the usability of the app. If we all use Ajax with a tiny bit of creative restraint, the Web of the future will certainly be a more enjoyable place to live and work.

Although the major premise of this book is to empower you to use Ajax without having to immerse yourself in the nitty-gritty details of asynchronous JavaScript coding, you may get motivated enough by the examples to dive into Ajax programming. If so, you will need to understand the XMLHttpRequest object inside and outthis object houses the primary functionality responsible for making Ajax work. This appendix provides you with a concise reference to the XMLHttpRequest object, along with a few helpful hints about how to best use its methods and properties. For a complete reference on all of the objects supported by the core JavaScript language, please refer to http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference.