WHAT IS AJAX?

                                 

Introduction:- AJAX stands for Asynchronous Javascript And XML. AJAX is used for fast creating dynamic web pages. It allow web pages to be updated asynchronously by exchanging some amount of data with the server behind the scenes. It is possible to update some parts of a web page without reloading the whole page. There are many web applications that run on ajax example:- gmail,facebook,twitter,google map, youtube etc.

Understanding synchronous and asynchronous:-

Synchronous:- The synchronous request blocks the client until the operation completes.

Asynchronous:-  Asynchronous request doesn’t block the client. At the time when the request is processing, user can perform another operation.

Some AJAX technologies:-

As we know ajax is not a technology but group of inter related technologies.some of the technologies is given below:

1.HTML/XHTML and CSS

2.XML and JSON

3.DOM

4.XMLHttpRequest

5.javascript

  1. HTML/XHTML and CSS:- These are the technologies which are used for developing front end of a websites and styling.
  2. XML and JSON:- It is used for carrying data to and from the server
  3. DOM:- It is used for dynamic display and interaction with the data.
  4. XMLHttpRequest:- It is used for asynchronous communication between client and server .
  5. Javascript:-It is a text based programming language used client side and server side both. Javascript allows to make the web pages imteractive.

HOW AJAX WORKS:-

AJAX communicates with the server using XMLHttpRequest. The user sends the request from the UI and the javascript call goes to XMLHttpRequest object. Then the Http request is send to the server. Then the server interact with the database and data is retrived. The server sends te data to the XMLHttpRequest callback function. And HTML and CSS data is displayed on the browser.

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