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Ajax (programming) From Wikipedia, the free encyclopedia Jump to: navigation, search "AJAX" redirects here. For other uses, see Ajax. Move protected

Ajax, sometimes written as AJAX (shorthand for asynchronous JavaScript and XML), is a group of interrelated web development techniques used on the client-side to create interactive web applications or rich Internet applications. With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. The use of Ajax has led to an increase in interactive animation on web pages[1][2] and better quality of Web services due to the asynchronous mode. Data is retrieved using the XMLHttpRequest object. Despite the name, the use of JavaScript and XML is not actually required, nor do the requests need to be asynchronous.[3] Contents [hide]

* 1 Constituent technologies * 2 History * 3 Technologies * 4 Rationale * 5 Critique * 6 See also * 7 Notes * 8 External links

[edit] Constituent technologies

Like DHTML and LAMP, Ajax is not a technology in itself, but a term that refers to the use of a group of technologies. Ajax uses a combination of:

* HTML and CSS for marking up and styling information. * The DOM accessed with JavaScript to dynamically display and interact with the information presented. * A method for exchanging data asynchronously between browser and server, thereby avoiding page reloads. The XMLHttpRequest (XHR) object is usually used, but sometimes an IFrame object or a dynamically added tag is used instead. * A format for the data sent to the browser. Common formats include XML, pre-formatted HTML, plain text, and JavaScript Object Notation (JSON). This data could be created dynamically by some form of server-side scripting.

[edit] History

Jesse James Garrett thought of the term "Ajax" while in the shower,[4] when he realized the need for a shorthand term to represent the suite of technologies he was proposing to a client.[5] While the term was coined in 2005,[6] alternative techniques for the asynchronous loading of content date back to the mid 1990s. Java applets were introduced in the first version of the Java language in 1995. These allow compiled client-side code to load data asynchronously from the web server after a web page is loaded.[7] In 1996, Internet Explorer introduced the IFrame element to HTML, which also enables this to be achieved.[8] In 1999, Microsoft created the XMLHTTP ActiveX control in Internet Explorer 5. This is now supported by Mozilla, Safari and other browsers as the native XMLHttpRequest object.[8][9] On April 5, 2006 the World Wide Web Consortium (W3C) released the first draft specification for the object in an attempt to create an official web standard.[10]

[edit] Technologies

The term Ajax has come to represent a broad group of web technologies that can be used to implement a web application that communicates with a server in the background, without interfering with the current state of the page. In the article that coined the term Ajax,[6] Jesse James Garrett explained that the following technologies are required:

* XHTML and CSS for presentation * the Document Object Model for dynamic display of and interaction with data * XML and XSLT for the interchange, manipulation and display of data, respectively * the XMLHttpRequest object for asynchronous communication * JavaScript to bring these technologies together

Since then, however, there have been a number of developments in the technologies used in an Ajax application, and the definition of the term Ajax. In particular, it has been noted that:

* JavaScript is not the only client-side scripting language that can be used for implementing an Ajax application. Other languages such as VBScript are also capable of the required functionality.[3] * XML is not required for data interchange and therefore XSLT is not required for the manipulation of data. JavaScript Object Notation (JSON) is often used as an alternative format for data interchange,[11] although other formats such as preformatted HTML or plain text can also be used.[

http://en.wikipedia.org/wiki/Ajax_%28programming%29