Ajax
" Group of interrelated web development techniques used for creating interactive
web applications or rich Internet applications. "
web applications or rich Internet applications. "
Ajax is a way of developing Web applications that combines:
- XHTML and CSS standards based presentation
- Interaction with the page through the DOM
- Data interchange with XML and XSLT
- Asynchronous data retrieval with XMLHttpRequest
- JavaScript to tie it all together
Ajax Acts as an Intermediary
The Ajax engine works within the Web browser (through JavaScript and the DOM) to render the Web application and handle any requests that the customer might have of the Web server. The beauty of it is that because the Ajax engine is handling the requests, it can hold most information in the engine itself, while allowing the interaction with the application and the customer to happen asynchronously and independently of any interaction with the server.
Asynchronous
This is the key. In standard Web applications, the interaction between the customer and the server is synchronous. This means that one has to happen after the other. If a customer clicks a link, the request is sent to the server, which then sends the results back.
With Ajax, the JavaScript that is loaded when the page loads handles most of the basic tasks such as data validation and manipulation, as well as display rendering the Ajax engine handles without a trip to the server. At the same time that it is making display changes for the customer, it is sending data back and forth to the server. But the data transfer is not dependent upon actions of the customer.
Ajax is Not New Technology
Ajax is instead a new way of looking at technology that is already mature and stable.
Benefits of Ajax
- Ajax provides a mechanism to mix and match xml with xhtml.
- Ajax significantly reduces having to continually fetch things from a server (remote iframe scripting is reasonably comparable here).
- Ajax overcomes some speed bottlenecks that traditional Web development has fallen prey too. In most instances an Ajax based site will load quicker than a comparable traditional Web site.
- When done well, Ajax significantly reduces initial load times.