On the surface, Ajax is the acronym for Asynchronous Javascript and XML. However, the acronym doesn’t describe an object, but a technique for web development. The definition incorporates a suite of technologies working in conjunction for web development. These techniques help produce more responsive and interactive web applications. Increased interactivity is required by web applications since so much of the marketplace and the services they require are currently electronic (the “e-market”) and conducted through the Internet.
Web applications allow applications to be accessed through web browsers rather than requiring software to be installed on individual computers. Webapps, as they are commonly referred to, are used to install and run many of the web-based activities that are now part of everyday life. For example, webapps are used to run Webmail, which includes all major e-communication applications that operate through a web browser, like Yahoo!Mail, Hotmail, and Gmail.
Webapps also help run on-line retail sales, auction sites, wikis, and Webblogs. They are essential to the many uses of the Internet we currently take for granted. The webapps supported by Ajax increase speed, interactivity and usability. By allowing web pages to exchange small bits of information with the server without the user’s knowledge, Ajax helps web applications seem more responsive and user-friendly. The entire page doesn’t need to be re-loaded every time a request is made. The ‘refresh’ function takes place behind the scenes.
This article will provide a general discussion of Ajax, its components and uses.
Background
The term Ajax was coined in 2005 by Jesse James Garret to describe a suite of technologies and approach he was presenting to a client. However, the impetus behind the development of Ajax was remote scripting initiated in 1995 by Microsoft. Remote scripting made it possible for interpreted programming languages to carry out functions through another program rather than by a computer processor that hardwired processing instructions.
Remote scripting allows scripts running inside a browser to communicate with and exchange information with a server. Microsoft’s Remote Scripting (MSRS, 1998) allowed for asynchronous loading of specified content without requiring full web page reload, similar to Ajax. Java applets allowed clients to communicate through Javascript, thereby facilitating asynchronous loading through a common language. This developed into Microsoft’s XMLHttpRequest which was introduced in 2000 on Microsoft’s Internet Explorer 5.
Online collaboration in the web development community through newsgroups and blogs, helped XMLHttpRequest replace Java applets for asynchronous web content loading. XMLHttpRequest is an API (application programming interface) that Javascript and certain web browser scripting languages use to move data between web servers (server-side) and users (client-side) using “http” (hypertext transfer protocol). This made communication easier, more standardized and, therefore, more translatable. It is one of the primary components of Ajax technology. However, there is much more technological collaboration that makes Ajax possible.
Components
The technological components that collaborate to make up Ajax technique are various. But, they all work together to increase web page user-friendly accessibility. XHTML is a markup language that provides a more rigid syntax than HTML. It is an intersection of HTML and XML. This provides a broader impact by using the standard XML library to communicate document content. Ajax also requires JavaScript or other client-side scripting language. Client-side scripting languages allow web pages to tailor their content according to user specifications. As previously mentioned, XMLHttpRequest allows asynchronous data exchange with the web server. XML provides a standardized format for client-server transfer of data.
Points of Interest
The primary reason for the development of Ajax was to by-pass existing page-loading requirements through HTML/HTTP-defined web pages. Ajax redefines user web-page interfaces as dynamic, intelligent and based on data. Web pages usually require the heavy operation of reloading the entire page each time a user needs a different dataset to request a different function. Ajax intuitively requests and uses data, through XMLHttpRequest, to make loosely coupled web pages act like tightly coupled applications.
The only interference is the lag time required for the communication to pass though the web browser and this happens almost instantaneously. This allows for a more intelligent recruitment of data based on user specifications. Perhaps the most popular applications of Ajax are observed in Google applications like Google Maps, Google Suggest, and Gmail.
