AJAX web application model
Ajax isn’t a technology. It’s really several technologies, each flourishing in its own right, coming together in powerful new ways. Ajax incorporates:
- standards-based presentation using XHTML and CSS;
- dynamic display and interaction using the Document Object Model;
- data interchange and manipulation using XML and XSLT;
- asynchronous data retrieval using XMLHttpRequest;
The classic web application model works like this: Most user actions in the interface trigger an HTTP request back to a web server. The server does some processing — retrieving data, crunching numbers, talking to various legacy systems — and then returns an HTML page to the client.
How Ajax works
An Ajax application eliminates the start-stop-start-stop nature of interaction on the Web by introducing an intermediary.
Ajax engine between the user and the server. It seems like adding a layer to the application would make it less responsive, but the opposite is true.
The Ajax engine allows the user’s interaction with the application to happen asynchronously independent of communication with the server. So the user is never staring at a blank browser window and an hourglass icon, waiting around for the server to do something.
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 stalling a user’s interaction with the application.