Ajax Programming

Asynchronous JavaScript and XML, in short AJAX is a web development model to create interactive web applications using a combination of technologies to dynamically display and interact with the information presented.

As a coming together of several technologies in powerful new ways, 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.

As part of the projects for our clients, we have developed several AJAX modules over the time some of which can be checked at the locations below.

A Brief overview of the concept of AJAX

Contrary to the classic web application model where most user actions in the interface trigger an HTTP request back to a web server with the server - after processing - returns an HTML page to the client, this model introduces an intermediary layer - an AJAX engine.

Instead of this additional layer between the user and the server rendering the system less responsive, it makes way for a whole way new approach towards web interaction.

At the start of the session, instead of loading a webpage, the browser loads an Ajax engine - written in JavaScript and usually tucked away in a hidden frame. This engine is responsible for both rendering the interface for the user and communicating with the server on the user's behalf. The Ajax engine allows the user's interaction with the application to happen asynchronously - independent of communication with the server.

The response to a user action that doesn't require an HTTP request trip back to the server - such as simple data validation, editing data in memory, and even some navigation - is handled by the AJAX engine itself. If the engine needs something from the server in order to respond - if it's submitting data for processing, loading additional interface code, or retrieving new data - the engine makes those requests asynchronously, usually using XML, without temporarily suspending the user's interaction with the application.

As a result of this, the user never has to stare at a blank browser window and an hourglass icon, waiting around for the server to do react.