Web systems day 01-Topics: Ajax

What is the goal of the use of Ajax (Asynchronous JavaScript + XML) in a Web application?

Goal of Ajax is to provide Web-based applications with responsiveness approaching that of desk-top applications.

Non-Ajax applications often have only one or a few server-side response programs, each of which produces significant content.

Ajax applications often have a much larger number of response programs, each of which is small and handles only requests for changes in one small part of a web page (e.g. Google maps web app).

Ajax applications often return JavaScript code to the client. Such code could be modified by an intruder to include destructive operations. To protect against this, any JavaScript code returned by the server must be scanned before it is interpreted.

Ajax is much faster for web applications that require user and server interactions.

Ajax requests and receives a small part of a document, hence results in much faster responses.

Ajax does not use any new programming languages or markup languages

AJAX is a technique for creating fast and dynamic web pages.

• Client side: JavaScript, XML, XHTML, DOM, CSS
• Server side: any (PHP, servlets, ASP.NET, etc.)

AJAX is based on internet standards, and uses a combination of:

•     XMLHttpRequest object (to exchange data asynchronously with a server)
•     JavaScript/DOM (to display/interact with the information)
•     CSS (to style the data)
•     XML (often used as the format for transferring data)

References

Robert W. Sebesta (2010). Programming the World Wide Web (5th ed.). Pearson Education, Inc.
http://www.w3schools.com/ accessed date 7 July 2012