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AJAX Resources
What is AJAX?
AJAX is an acronym for Asynchronous JavaScript and XML. AJAX is really not a new technology, but instead combines several existing technologies to provide a foundation for rich Internet applications.
The key benefit of AJAX is that information can be exchanged between the browser and the server without refreshing the entire page. This means that applications running in a browser using AJAX can be faster and more responsive and thus more closely resemble applications running on the desktop.
Another key point is that almost all recent browsers support the techniques utilized for AJAX. This means that users do not have to download plug-ins or install other software to make AJAX work.
How Does AJAX Work?
To best describe how AJAX works, it is helpful to first look at how 'normal' web applications work. When a user clicks on a non-AJAX link, the result is usually a request to the server for a page (i.e. a chunk of HTML and script code) that replaces the current page. When navigating to a completely different page this is appropriate. However, when a page just needs to update a small part of its content, reloading the whole page is overkill. This is why for example just changing a value in a drop-down list can result in the all-too-familiar delay as the browser goes to the server, clears out the current page and reloads that same page with just a few items changed.
Enter AJAX. When a user clicks on an AJAX link or control, a different type of request is made on the server. This type of request uses a special JavaScript command that does not result in the page being reloaded. An AJAX request happens behind the scenes or more technically - asynchronously. The information sent back from the server is not an entire page, but instead is usually XML that contains just the information that has changed on the page.
How to use AJAX in an Application?
AJAX sounds perfect right? Well it looks that way, until one considers that most of the mechanism for sending an AJAX request, handling it on the server, returning the XML response and decoding it in the browser needs to be either developed from scratch or at least customized for every application. Reusable AJAX libraries are just starting to emerge and can reduce the work, but for the most part they still require the application developer to understand a lot of AJAX details.
AJAX and JavaServer Faces
At Simplica, we believe application developers should be spared the low-level AJAX details. The best way to do this is to utilize an overall application framework that encapsulates AJAX into its event system and component model. We think JavaServer Faces provides the best fit of power and flexibility to accomplish this.
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