what is ajax?
Hello,
We were getting a number of querries from our clients and
friends, asking about what AJAX is? With the development of
Microsoft's Live, everyone is going crazy about AJAX. So, we at
Xaprio Solutions thaught of publishing this small article about
AJAX, which will help you guys understand it better.
Like DHTML, LAMP, or SPA, Ajax is not a technology in itself,
but a term that refers to the use of a group of technologies
together. In fact, derivative/composite technologies based
substantially upon Ajax, such as AFLAX, are already appearing.
The Term AJAX refers to, Asynchronous JavaScript and XML.
For a number of tasks, only small amounts of data need to be
transferred between the client and the server, allowing a number
of Ajax applications to perform almost as well as applications
executed natively on the user's machine. This has the effect
that pages need only be incrementally updated in the user's
browser, rather than having to be entirely refreshed. "Every
user's action that normally would generate an HTTP request takes
the form of a JavaScript call to the Ajax engine instead", wrote
Jesse James Garrett, in the essay that first defined the term.
"Any response to a user action that doesn't require a trip back
to the server -- such as simple data validation, editing data in
memory, and even some navigation -- the engine handles on its
own. If the engine needs something from the server in order to
respond -- if it's submitting data for processing, loading
additional interface code, or retrieving new data -- the engine
makes those requests asynchronously, usually using XML, without
stalling a user's interaction with the application."
Traditional web applications essentially submit forms, completed
by a user, to a web server. The web server does some processing,
and responds by sending a new web page back. Because the server
must send a whole new page each time, applications run more
slowly and awkwardly than their native counterparts.
Ajax applications, on the other hand, can send requests to the
web server to retrieve only the data that is needed, and may use
SOAP or some other XML-based web services dialect. On the
client, JavaScript processes the web server's response, and may
then modify the document's content through the DOM to show the
user that an action has been completed. The result is a more
responsive application, since the amount of data interchanged
between the web browser and web server is vastly reduced. Web
server processing time is also saved, since much of it is done
on the client.
The earliest form of asynchronous remote scripting, Microsoft's
Remote Scripting, was developed before XMLHttpRequest existed,
and made use of a dedicated Java applet. Thereafter, remote
scripting was extended by Netscape DevEdge at around 2001/2002
by use of an IFRAME instead of a Java applet.