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what is ajax?
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By nipun
[Hits: 29787]
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Hello,
We were getting a number of querries from our clients andfriends, asking about what AJAX is? With the development ofMicrosoft's Live, everyone is going crazy about AJAX. So, we atXaprio Solutions thaught of publishing this small article aboutAJAX, 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 technologiestogether. In fact, derivative/composite technologies basedsubstantially 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 betransferred between the client and the server, allowing a numberof Ajax applications to perform almost as well as applicationsexecuted natively on the user's machine. This has the effectthat pages need only be incrementally updated in the user'sbrowser, rather than having to be entirely refreshed. "Everyuser's action that normally would generate an HTTP request takesthe form of a JavaScript call to the Ajax engine instead", wroteJesse James Garrett, in the essay that first defined the term."Any response to a user action that doesn't require a trip backto the server -- such as simple data validation, editing data inmemory, and even some navigation -- the engine handles on itsown. If the engine needs something from the server in order torespond -- if it's submitting data for processing, loadingadditional interface code, or retrieving new data -- the enginemakes those requests asynchronously, usually using XML, withoutstalling a user's interaction with the application."
Traditional web applications essentially submit forms, completedby a user, to a web server. The web server does some processing,and responds by sending a new web page back. Because the servermust send a whole new page each time, applications run moreslowly and awkwardly than their native counterparts.
Ajax applications, on the other hand, can send requests to theweb server to retrieve only the data that is needed, and may useSOAP or some other XML-based web services dialect. On theclient, JavaScript processes the web server's response, and maythen modify the document's content through the DOM to show theuser that an action has been completed. The result is a moreresponsive application, since the amount of data interchangedbetween the web browser and web server is vastly reduced. Webserver processing time is also saved, since much of it is doneon the client.
The earliest form of asynchronous remote scripting, Microsoft'sRemote Scripting, was developed before XMLHttpRequest existed,and made use of a dedicated Java applet. Thereafter, remotescripting was extended by Netscape DevEdge at around 2001/2002by use of an IFRAME instead of a Java applet.
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