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AJAX - A New Approach to Web Applications

 

Introduction

Web application designing has by far evolved in a number of ways since the time of its birth. To make web pages more interactive various techniques have been devised both at the browser level and at the server level. The introduction of XMLHttpRequest class in the Internet Explorer 5 by Microsoft paved the way for interacting with the server using JavaScript, asynchronously. AJAX, a shorthand for Asynchronous Java And XML, is a technique which uses this MLHttpRequest object of the browser features plus the Document Object Model and DHTML and provides for making highly interactive web applications in which the entire web page need not be changed by a user action, only parts of the page are loaded dynamically by exchanging information with the server. This approach has been able to enhance the interactivity and speed of the web applications to a great extent. Interactive applications such as Google Maps, Orkut, Instant Messengers are making extensive use of this technique. This report presents an overview of the basic concepts of AJAX and how it is used in making web applications.

Creating Web applications has been considered as one of the most exciting jobs under current interaction design. But, Web interaction designers can't help feel a little envious of their colleagues who create desktop software. Desktop applications have a richness and responsiveness that has seemed out of reach on the Web. The same simplicity that enabled the Web's rapid proliferation also creates a gap between the experiences that can be provided through web applications and the experiences users can get from a desktop application.

In the earliest days of the Web, designers chafed against the constraints of the medium. The entire interaction model of the Web was rooted in its heritage as a hypertext system: click the link, request the document, wait for the server to respond. Designers could not think of changing the basic foundation of the web that is, the call-response model, to improve on the web applications because of the various caveats, restrictions and compatibility issues associated with it.

But the urge to enhance the responsiveness of the web applications, made the designers take up the task of making the Web work the best it could within the hypertext interaction model, developing new conventions for Web interaction that allowed their applications to reach audiences who never would have attempted to use desktop applications designed for the same tasks. The designers' came up with a technique called AJAX, shorthand for Asynchronous Java And XML, which is a web development technique for creating interactive web applications. The intent of this is to make web pages feel more responsive by exchanging small amounts of data with the server behind the scenes, so that the entire web page does not have to be reloaded each time the user makes a change. This is meant to increase the web page's interactivity, speed, and usability. AJAX is not a single new technology of its own but is a bunch of several technologies, each ourishing in its own right, coming together in powerful new ways.

What is AJAX?

AJAX is a set of technologies combined in an efficient manner so that the web application runs in a better way utilizing the benefits of all these simultaneously. AJAX incorporates:

1. standards-based presentation using XHTML and CSS;
2. dynamic display and interaction using the Document Object Model;
3. data interchange and manipulation using XML and XSLT;
4. asynchronous data retrieval using XMLHttpRequest;
5. and JavaScript binding everything together.