In classical web applications, when we submit a form, although most of the page remains the same, whole page is reloaded from the server. This causes long waiting times and waste of bandwidth. The combination of a group of web technologies known as AJAX is come up with to create interactive web applications. With AJAX, web applications can retrieve data asynchronously from server while not refreshing the whole page.
AJAX is a shorthand for asynchronous JavaScript and XML. AJAX is not a technology in itself, but a term that refers to the use of a group of technologies together.
So what AJAX is made up of? Jesse James Garrett gave his definition:
1. XHTML and CSS for presentation
2. the Document Object Model for dynamic display of and interaction with data
3. XML and XSLT for the interchange, manipulation and display of data, respectively
4. the XMLHttpRequest object for asynchronous communication
5. JavaScript to bring these technologies together
Since AJAX was coined, however, there have been a lot of developments. JavaScript is not the only client-side scripting language used for AJAX application, other languages such as VBScript can also be used. And XML is not required for data interchange, JavaScript Object Notation(JSON) is often used as an alternative format for data interchange.
Here comes three examples of using AJAX to show you what can be done with.
1. Google Maps
You can drag & drop and resize the map, just like desktop applications.
2. Gmail
You can use all of the mail functions without leaving the Gmail page.
3. Flickr
Flickr is a photo storage and display program that uses AJAX.
Resources from the web
1. AJAX Basics is a presentation from Sang Shin.
2. AJAX introduces to you the essential of AJAX.
3. Mastering AJAX, Part 1 demonstrates how AJAX make extremely efficient Web development an easy reality.
4. AJAX Basics tells you how AJAX works, how to create cross-browser AJAX and how to send data using Head, Get, Post.
5. AJAX Tutorial for Java Programmer covers “Hello, World” to “Optimization Issues”.
6. 70 Popular Ajax Applications’ Demo and Source Code shows what AJAX is capable of by examples.
7. JavaScript Tutorial: AJAX Tutorial provides two examples with source code.
8. There are various AJAX tutorials and other resources in the site of ajaxprojects.
9. 60 More AJAX Tutorials is intended for you who learn best by examples.
10. There are various AJAX Lessons, Tutorials and Workshops in the site of ajaxlessons.
