Asynchronous Java Script and XML (Ajax): Technologies, Advantages, Utilities and some disadvantages
Ajax (Asynchronous Java Script and XML) it isn’t a technology itself. Ajax embraces a diversity of web technologies which are able to communicate with the server without disturbing with the current state of the page. Since 2005 Ajax has been improving its techniques for the asynchronous of content and recently Ajax is more powerful thanks to the Microsoft Remote Scripting. Ajax is capable to run scripts inside browsers such as Mozilla, Internet Explorer and others and then communicate with the server acting as a faster and more elegant technique. The data loaded in the page is inserted by a java applet.
Which technologies are represented by Ajax?
There are a large group of technologies which are part of the scope of Ajax. These technologies are XHTML, CSS, Document Object Model, XML, XSLT, XMLHttpRequest, JavaScript, VBScript, iFrame, Java Script Object Notation. I would like describe all these more in detail:
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XHTML & CSS: Both are used to define the presentation of the page.
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Document Object Model: It is used to interact with data and provide dynamic display of information.
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XML & XSLT: The first is for the interchange of data and the second one is used for manipulate the data.
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XMLhttpRequest: This is a great technology consisting in an object for asynchronous communication.
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JavaScript: It is the script that can put together all the aforementioned technologies.
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IFrame: HTML element capable of embed a document of HTML in other one.
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JavaScript Object Notation: Is used as an alternative to interchange information. It represents simple data structures that can be applied in applications based in Ajax.
Advantages and utilities:
We can start mentioning that Ajax is based on an open standard which has a great significance for users and developers. These standards support a wide variety of browsers, applications and platforms and are one of the most important advantages of Ajax.
Furthermore, with the traditional techniques the content would have to be loaded again on every request but Ajax only reloads the content that requires to be updated. Moreover, web browsers can interact faster with clients through the asynchronous request responding quickly and reloading the sections of the pages individually. Ajax can reduce the connections to the server; even by using CSS the connection is produced only one time.
Some disadvantages:
Ajax is good but unfortunately has some disadvantages that users don’t like. For instance if you try to go back in your browser it won’t be possible because the pages created dynamically do not register themselves with the browser. On the other hands it is complicated to bookmark a specific state of an application. Also the W3C don’t recommend Ajax to be used across domains. Finally, something that occurs frequently is that users having disabled the JavaScript in their browsers or browser which can’t support JavaScript will not be able to use this functionality.
