What is AJAX ...

Ajax (sometimes called Asynchronous JavaScript and XML) is a way of programming for the Web that gets rid of the hourglass. Data, content, and design are merged together into a seamless whole. When your customer clicks on something on an Ajax driven application, there is very little lag time. The page simply displays what they’re asking for. If you don’t believe me, try out Google Maps for a few seconds. Scroll around and watch as the map updates almost before your eyes. There is very little lag and you don’t have to wait for pages to refresh or reload.

Ajax is a way of developing Web applications that combines:

    * XHTML and CSS standards based presentation
    * Interaction with the page through the DOM
    * Data interchange with XML and XSLT
    * Asynchronous data retrieval with XMLHttpRequest
    * JavaScript to tie it all together

In the traditional Web application, the interaction between the customer and the server goes like this:

   1. Customer accesses Web application
   2. Server processes request and sends data to the browser while the customer waits
   3. Customer clicks on a link or interacts with the application
   4. Server processes request and sends data back to the browser while the customer waits

Asynchronous

This is the key. In standard Web applications, the interaction between the customer and the server is synchronous. This means that one has to happen after the other. If a customer clicks a link, the request is sent to the server, which then sends the results back.

With Ajax, the JavaScript that is loaded when the page loads handles most of the basic tasks such as data validation and manipulation, as well as display rendering the Ajax engine handles without a trip to the server. At the same time that it is making display changes for the customer, it is sending data back and forth to the server. But the data transfer is not dependent upon actions of the customer.

An Ajax framework is a framework that helps to develop web applications that use Ajax, a collection of technologies used to build dynamic web pages on the client side. Data is read from the server or sent to the server by JavaScript requests. However, some processing at the server side may be required to handle requests, such as finding and storing the data. This is accomplished more easily with the use of a framework dedicated to process Ajax requests

AJAX EXAMPLES :

http://maps.google.com/

http://www.flickr.com/

http://www.backpackit.com/

http://www.gmail.com/

source: avaricesoft.wordpress

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