Friday, February 11, 2011

Programming in Ajax


AJAX stands for Asynchronous Javascript And XML. It is a group of interrelated web developmenttechniques used on the client-side to create interactive web applications.
# It is all about updating parts of a web page, without reloading the whole page.
# AJAX is not a new programming language, but a new way to use existing standards.
# Before you continue you should have a basic of HTML / XHTML, CSS and JavaScript/DOM.
# AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
# Google Maps, Gmail, orkut, Youtube, and Facebook are the excellent examples of applications implementing AJAX.

 In the classic web application, communication between the client (the browser) and the web server were performed directly, using HTTP requests.

   # Classic Web Application Model: When the visitor requests a page, the server will send the full HTML and CSS code at once. Every time user requests data, same process occur which creates delay in response.

    # AJAX Application Model: When using AJAX the page is loaded entirely only once, the first time it is requested. All requests for data to the sever will then be sent as JavaScript calls to this engine. The AJAX engine then requests information from the web server asynchronously. Thus, only small page bits are requested and sent to the browser, as they are needed by the user.


The engine then displays the information without reloading the entire page. This leads to a much more responsive interface, because only the necessary information is passed between the client and server, not the whole page. This produces the feeling that information is displayed immediately, which brings web applications closer to their desktop relatives.

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