Ajax as Web application Development

AJAX is a web application development technique which encompasses different technologies which make it more interesting and fun. It has the following technologies :

1. JavaScript
2. XML
3. CSS
4. W3C DOM
5. XMLHttpRequest

Since it embraces so many technologies that's why it is neither easy nor tough. In AJAX, "A" stands for "Asynchronous" that means  sending data from the browser and  response send back from the server are not sequential. When user make requests then the server can do its own work or it may fulfill other requests. Similarly when server is busy in responding user may make further requests that means no request or response is synchronous or depending on each other. 

Data Exchange in AJAX

XML: In AJAX, data is exchanged with the help of XML files, there are many alternate techniques are also available like CSV, JSON etc.

Because of the simplicity of XML, it is becoming the new standard of  exchanging data between server and browser. XML is very easy to reformat, reuse.

DOM: The DOM (Document Object Model) is the object oriented representation of XML & HTML documents, and provides an API for changing the content, structure, and style. The DOM represents HTML & XML documents as object hierarchy, which is easy to parse by XML tools.

CSS: CSS (Cascading Style Sheet) is used in web site for designing purpose, we can use CSS in almost all aspects of the way the web pages look, size, color, width, length etc. of text box, input area,..etc. that means every attribute of every user interface. In AJAX it is very useful to use CSS, you can implement CSS as color changing on validation checking in a registration form and other.

XMLHttpRequest: Unlike other usual web pages, with  AJAX, JavaScript communicates with server using JavaScript's XMLHttpRequest object. With the help of XMLHttpRequest a web page can send request and get a response from the server without refreshing the page. This object is supported by all the leading web browsers.

JavaScript: We can say that JavaScript is the pivot point of AJAX . IT performs the following role in AJAX:

1. Handling  XMLHttpRequest made HTTP requests
2. Using DOM, XSLT or any other method, parsing the response come from the server.
3. Presenting the response from server to user interface.

Check out the examples in next page: