| |
| |
Ajax |
AJAX
Asynchronous JavaScript and
XML
Speed and Dexterity for futuristic web enabled applications…
A conventional web application
essentially submits forms, filled by users to a web server, web
page back. As re slowly.
Ajax on the other hand enables web applications to respond more
quickly to numerous types of user interface and to avoid continually
transferring unchanged information across the network. Ajax technologies
are open and therefore are compatible with all JavaScriptenabled
browsers regardless of the operating systems.
What is Ajax?
Ajax is a blend of several technologies. Ajax stands for-Asynchronous
JavaScript and XML. It is a technique used to develop web based
applications. It incorporates:
|
Features:
 |
XHTML and CSS for marking up and styling information. |
|
The Document Object Model, which is manipulated through JavaScript
to dynamically demonstrate and interrelate with the information
presented |
|
Retrieval of asynchronous data using XMLHttpRequest |
|
XML is generally used, though any format works; counting preformatted
HTML, plain text, JSON and even EBML.
Web applications developed on Ajax technology can perform most of
the functions that the native application of the user’s system
can. This is because while interacting with the server on which they
reside, a very small amount of data is exchanged back and forth at
a time. This leads to pages being updated in the user’s browser
only, rather than being refreshed completely. It’s a model modified
from the web’s unique use as a hypertext medium.
Functional
aspects:
In applications developed through this technology every user’s
action that would generally generate an HTTP request gets transformed
into JavaScript and summons the Ajax engine.
To enhance the functional timing, any reaction to user’s action
that does not need a trip back to the server – such as simple
data confirmation, data edition in memory, and a few navigations –
are handled by the engine on its own.
If the engine requires some information from the server so as to present
a response, such as: submission of data for processing, loading added
interface code, or recovering new data — the engine places these
requests synchronously, generally using XML, without delaying a user’s
interaction with the application.
Accessibility:
Using Ajax technology in web applications proves to be a major challenge
for developers involved in adhering to WAI convenience guidelines.
Developers need to offer fallback options for users on other platforms
or browsers, as most methods of Ajax execution rely on characteristics,
present only on desktop graphical browsers.
Web developers employ Ajax in some cases to offer content only to
particular portions of a web page, allowing data management without
incurring the cost of re-rendering the complete page on the web browser.
Numerous famous applications have been developed by deploying the
Ajax such as: Google Maps and Gmail, Yahoo’s Flicker, America
Online’s AIM Mail, 24SevenOffice and Microsoft’s Virtual
Earth. These prestigious examples of Ajax usage demonstrate flexibility
and effectiveness of the web programming model.
Browsers
Supporting Ajax:
|
Apple Safari 1.2 and above |
|
Microsoft Internet Explorer 5.0 and above |
|
Mozilla/Mozilla Firefox 1.0 and above |
|
Netscape 7.1 and above |
|
Konqueror |
|
Opera 7.6 and above |
|
Opera mobile browser 8.0 and above |
How is Ajax Different?
An Ajax application reduces the interaction time on the web
by introducing a mediator – an Ajax engine – connecting
the user and the server. Rather than loading a webpage, at the start
of the session, the browser loads an Ajax engine which is written
in JavaScript and generally stored in a hidden frame. This engine
is responsible for both depicting the interface the user sees as well
as communicating with the server on the user’s behalf.
The Ajax engine allows the user’s communication with
the application to happen asynchronously without affecting communication
with the server. This leads to users never staring at a blank browser
window.
All user actions that would generally create an HTTP request
take the form of a JavaScript call to the Ajax engine. Any reply to
a user action that doesn’t necessitate a trip back to the server
is handled by the engine on its own. Such actions include: simple
data validation, editing data in memory, and even some navigation.
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. |
| |
|
|
About us 
