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What is Ajax?
both something old and something new - old because already existing technologies
are used, but new because it combines these existing technologies into
techniques that very few considered previously.
" Ajax is a technology that complements Web 2.0
and the integration of many web services at once."
Ajax is a technique for creating fast and dynamic web pages. In
other words, Ajax allows web pages to be updated asynchronously by exchanging
small amounts of data with the server behind the scenes. This means that it is
possible to update parts of a web page, without reloading the whole page.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and
What is the need of Ajax?
information from a database or a file on the server, or send user information to
a server, its important to make an HTML form and GET or POST data to the server.
Wait for the server to respond, then a new page will load with the results when
clicking Ok button to send the information. Because the server returns a new
page can make a request to, and get a response from a web server - without
reloading the page. The user will stay on the same page, and he will not notice
that scripts request pages, or send data to a server in the background. By using
the XMLHttpRequest object, a web developer can update a page with data from the
server after the page has loaded. The XMLHttpRequest object is supported in
Internet Explorer 5.0+, Safari 1.2, Mozilla 1.0 / Firefox, Opera 8+, and
History of Ajax-
During browser innovation, Netscape added a feature known as Live Script
small scripts in web pages so that they could continue to do things after
youâ€™d downloaded them.
Ajax came when the Internet Explorer introduced the concept of IFrame
element. Microsoft introduced another technique, called as Microsoftâ€™s Remote
Scripting that technique involved the pulling of data through means of Java
Applet which communicated with the client side using scripting language like
As soon Microsoft introduced new XMLHttpRequest object that acts as an
ActiveX control in the Internet Explorer. Finally, in the year 2006, the W3C
(World Wide Web Consortium) announced the release of the first draft that
included the specification for the object (XMLHttpRequest) and made it an
official web standard.
AJAX (first coined in the year 2005) is not a new programming language but
a relatively new technique for creating faster, better and dynamic web
applications. If you have the basic understanding of HTML, XHTML, XML and
In Figure there is a browser. The
browser has two pieces of content: Content 1 and Content 2. Each piece of
content is fetched from a different server. Content 2 is fetched from a server
that also has two pieces of content, which are also retrieved from separate
servers. From an architectural point of view, Ajax implements the Pipes and
The data is fetched from the server by using a
Representational State Transfer (REST) architecture style. The essence of REST
is to create a simpler web services architecture by using Hypertext Transfer
Protocol (HTTP). REST is used solely for the transfer of data, and in particular
is used extensively with Ajax applications. The overall idea is to generate
content and to have that content filtered and processed. The filtered and
processed content serves as an information basis, where another process acts as
a client that filters and processes the information. The filtered and processed
information acts as an information basis for another client. Content is fluid
and constantly modified.
How Ajax Works?
Advantages of Ajax-
Architecture with user participation
Use of Web as the platform
Software delivered as a service instead of packaged software
Disadvantages of Ajax-
Requests ActiveX to be enabled in IE 5 and 6 Is only available in newer
versions of Opera and Safari has small implementation differences between
Prohibits no synchronous requests doesn't work with large requests/results
requires server pages to be designed to work with cookie requests requires
polling on the client Can make only GET HTTP requests
Ajax on Mobile-
Pocket PC and Smart phone Devices (2003 and later) support
AJAX. By storing an AJAX application on the mobile phone and allowing
XML-communication with a Web-server, the traditional bandwidth constraints
become less of an issue. This also enables transparent updating of information
pushed to the mobile phone.
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