AJAX allows for asynchronous data exchange in the background without interfering with the display and behavior of the existing page. It combines technologies like XML, JavaScript, HTML and CSS to retrieve data from the server to update portions of a web page without reloading the entire page. This improves usability, interactivity and performance of web applications.

1. AJAX Basics

2. History of AJAX
 Starts with web pages
 Static web pages
 Static html page is loaded
 No interaction with user
 Dynamic web pages
 html page is generated dynamically
 Interaction with user
 Becomes slower as functionality increases
 Speed becomes untolerable, so AJAX has been born

3. What is AJAX?
 Asynchronous JavaScript and XML (AJAX).
 Not a stand-alone language or technology.
 Combines a set of known technologies in order to create faster and
more user friendly web pages.
 Client side technology.
 Makes web pages more responsive by exchanging small amounts of
data.
 Allows the web page to change its content without refreshing the
whole page.
 Web browser technology independent of web server software.

4. What is So Cool about AJAX?
 Connection between client side script and server side script.
 Better user experience.
 More flexibility.
 More options.

5. AJAX Technologies
 Extensible Markup Language (XML)
 Hyper Text Markup Language (HTML)
 JavaScript
 Cascading Style Sheet (CSS)
 ASP or JSP (server side)

6. AJAX Examples
Google Maps
User can drag the entire map by using the mouse instead of clicking on a
button or something
Google Suggest
Google will offer suggestions.
Gmail
Gmail is a new kind of webmail, built on the idea that email can be more
intuitive, efficient and useful
Yahoo Maps (new)
Now it's even easier and more fun to get where you're going!

7. Why it is Popular?
 Google helped popularize, and legitimize it in Gmail.
 Increase Usability of Web Applications.
 Rich Internet applications without Flash.
 Save Bandwidth.
 Download only data you need.
 Faster interfaces.

8. Advantages of AJAX
 Better internet Application
 Requests only the content that needs to be updated
 Respond quickly to the input
 Page can be reloaded individually
 Reduces connections to the server
Prevents unnecessary reloading of a page

9. AJAX Browser Support
Internet Explorer Opera
Mozilla Firefox Flock
Safari Netscape

10. How AJAX Works?
 AJAX is based on Javascript, and the main functionality is to access
the web server inside the Javascript code.
 We access to the server using special objects; we send data and
retrieve data.
 When user initiates an event, a javascript function is called which
accesses server using the objects.
 The received information is shown to the user by means of the
Javascript’s functions.

11. Working…..
The client process the returned
xml document using JavaScript
Using JavaScript, an and updates the page content
instance of the xmlHttp
request is then sent
Internet
The Http Request is processed by
the server. A response is created
And returned as xml data to the
client

12. Working cont…..
XMLHTTPRequest Object
Heart of the AJAX Engine and it is responsible to carry the HTTP request
to the server asynchronously.
Talking with the Server
XMLHTTPRequest talks with the server with its appropriate methods and
properties asynchronously at the backside.
Server Response
As per the Server script is concerned the request from the XMLHTTPRequest is
just another HTTP request.
Dealing with the Server Response
Once after the AJAX Engine gets notified about the successful execution.
It modifies the data according to the functionality and keeps in place.

13. AJAX Server
AJAX is about creating clever applications that can use the data.
Requesting Text Files
Many AJAX applications requests pure text files to retrieve data for
the application.
Requesting XML Files
A very common AJAX method is to request XML files to retrieve
application data.

14. Requesting ASP or PHP Files
Requesting an ASP or PHP file is the most common way to access
database information.
Requesting HTML Files
Requesting HTML files is a common method for filling out different
information on a web page.
Submitting Forms
With AJAX you can easily submit form data without having to reload the
page.

15. Ajax Frameworks
Framework Framework Example
JavaScript Yahoo User Interface Library (YUI)
Java Google Web Toolkit
.NET ASP.NET AJAX
PHP Sajax
Python Pyjamas

16. Ajax Security
Server Side
AJAX-based Web applications use the same server side security
schemes of regular Web applications.
Client Side
Downloaded JavaScript code is constrained by sand-box security
model and can be relaxed for signed JavaScript.

17. Issues with Ajax
 Complexity is increased
 AJAX-based applications can be difficult to debug, test, and maintain
 Toolkits/Frameworks are not mature yet
 No standardization of the XMLHttpRequest yet
 No support of XMLHttpRequest in old browsers
 JavaScript technology dependency & incompatibility
 JavaScript code is visible to a hacker

18. Thank You