1.3. Technologies of AJAX
If you search the Internet for AJAX, you are likely to notice a large number of items popping up under the AJAX name that don't seem to fit my definition. In most cases, these libraries provide the related functionality needed to finish your AJAX application, but other times, these libraries are just someone trying to jump on the AJAX bandwagon. When looking at these libraries and techniques, I divide them into three groups:
Most of the technologies directly related to AJAX are those that make up the "asynchronous" and the "XML" parts of the AJAX acronym. These are the libraries and techniques that provide the communication layer and the ways to encode the data that moves over it. In many cases, this is the XMLHttpRequest object, but IFrames are also popular, and cookies or embedded ActiveX/Java are yet another possibility. The "X" in AJAX is the technique used in the data encoding, and it's an area with a huge number of possibilities. Data can be transferred as plain text, HTML, XML, or any other type of format that might be convenient for the situation.