Ajax has become one of the leading stars in online development, the technology behind is no
other then XML_HTTP_REQUEST & Javascript comining both of these, we get a delicous receipe. Just to give a little examples of what ajax is being used for can be seen at Google's Email service - www.Gmail.com. you can see after logging in you are quickly redirected to your Inbox folder; you can then check your emails, delete them. If you choose to delete them
they are deleted on-the-fly without refreshing the page. almost like a desktop application (Outlook for example). These are some neat functionality that have been seeked for such a long time and now everyone can enjoy them.
There are some down-falls though too, when using ajax based technology on your application people should also consider how it will impact their users (application users); there are many dial-up users who may surely have expereinced trouble using Ajax Applications because these ajax application requires High Speed Internet connection - those who don't have that see unexpectable results.
Ajax, which consists of HTML, JavaScript™ technology, DHTML, and DOM, is an outstanding approach that helps you transform clunky Web interfaces into interactive Ajax applications. The author, an Ajax expert, demonstrates how these technologies work together -- from an overview to a detailed look -- to make extremely efficient Web development an easy reality. He also unveils the central concepts of Ajax, including the XMLHttpRequest object.
However, Ajax is far more than just a fad; it's a powerful approach to building Web sites and it's not nearly as hard to learn as an entire new language.
Before I dig into what Ajax is, though, let's spend just a few moments understanding what Ajax does. When you write an application today, you have two basic choices:
- Desktop applications
- Web applications
These are both familiar; desktop applications usually come on a CD (or sometimes are downloaded from a Web site) and install completely on your computer. They might use the Internet to download updates, but the code that runs these applications resides on your desktop. Web applications -- and there's no surprise here -- run on a Web server somewhere and you access the application with your Web browser.
More important than where the code for these applications runs, though, is how the applications behave and how you interact with them. Desktop applications are usually pretty fast (they're running on your computer; you're not waiting on an Internet connection), have great user interfaces (usually interacting with your operating system), and are incredibly dynamic. You can click, point, type, pull up menus and sub-menus, and cruise around, with almost no waiting around.
On the other hand, Web applications are usually up-to-the-second current and they provide services you could never get on your desktop (think about Amazon.com and eBay). However, with the power of the Web comes waiting -- waiting for a server to respond, waiting for a screen to refresh, waiting for a request to come back and generate a new page.
Obviously this is a bit of an oversimplification, but you get the basic idea. As you might already be suspecting, Ajax attempts to bridge the gap between the functionality and interactivity of a desktop application and the always-updated Web application. You can use dynamic user interfaces and fancier controls like you'd find on a desktop application, but it's available to you on a Web application.
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