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Ajax

By Roy Tennant - Posted on December 1st, 2005
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Executive Summary

Ajax refers to the use of several technologies to create highly interactive web sites. Rather than completely reloading a web page when the user clicks on something, a request is sent out to the server by Javascript, using an XML-based protocol, with the resulting response processed and displayed by the Javascript directly in the web page already displayed to the user.

What It Is

Ajax actually refers to three technologies used in concert to enable interactive web pages and web pages that combine content from two or more sources in one display. Javascript is the programming language that enables web developers to control the action. XMLHTTPRequest is the protocol that is used to send the user input (such as clicking on a control) to a remote server and receive information back. Web Services is what defines the type of information package that is delivered for the Javascript code in the web page to process and dynamically update the web page.

What Can Be Done With It

Using Ajax technologies, you can create web pages that are very interactive and responsive, since a web page reload is not required to update content on the page. You can also use Ajax to pull data or content in from other sites, combining it with other data or content to create a new presentation (see, for example, the Chicago Crime site below under Examples). The best way to get a sense of what Ajax can do is to see how it is used in practice (see Examples below).

Examples

Who Should Be Using It

Those who wish to create interactive web pages and can either do so in a manner that does not violate web accessibility guidelines or who do not care if such guidelines are violated.

Related Technologies

  • Javascript
  • XMLHTTPRequest
  • Web Services

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