First of all AJAX is not a single technology…its a combination of many technologies which are working together in their own way to bring out powerful ways of designing web applications.
AJAX mainly includes
— Usage of all web standards using XHTML and CSS.
— Changing data and managing those data using XML and XLST.
— Using the XMLhttpRequest Object for asynchronous data retrieval.
— Bringing dynamic display and interaction using DOM (Document Object Model).
How is it different from the Old web model?
Here mainly I have to go for the negative points of our usual web environment and its bad affects. Firstly we are making our clients or users to wait for long at the time loading .The only solution for making our web application fast is to compare our web application with the usual windows based application and compare the form loading speeds. And the best method will be to restrict the HTTP requests to the web server whenever there is a processing. So that will be including processing in client side itself if we can.
What AJAX provides?
Here we have found an end to the up down up down communication to the web server and the client machine when we use a web application. Users don’t have to go to the web server to do some processing every time they do anything on the server.
Here there is an introduction of a “AJAX ENGINE ” which now plays a role in between the user and the web server. The AJAX engine is loaded when the web session starts .It is responsible for rendering the user interface by communicating with the web server on the user’s behalf. The Ajax engine works in a way so that the users interaction with the web server happens asynchronously – independent with the communication with the web server.
The following image will make my points a bit more clear.