Ajax for Dummies - What is Ajax Technology and When to use it and when not to use it

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Ok, the title unintentionally become a little long as per my intentions but whatever. Sometime back I had written an article on What is Web 2.0 ? Meaning of Web 2.0 and What exactly it is IMO ? where I had put my thoughts on web 2.0 and why web 2.0 is not ajax(Ajax is just a part of web 2.0, it was there even before the term was coined actually)

Some facts about Ajax

Ajax – it’s the same with AJAX – is used for creating web applications that are interactive. Therefore, Ajax is a web development technique, which has become very popular in the last years. Ok, ok, now that you understood part of what Ajax is, you must be wondering why it is so good. Well, using Ajax with your web pages will make them feel more responsive by simply working “behind the scenes” (small amounts of data are exchanged with the server all the time). Why is this helpful? This way, whenever a user requests a change on a certain page, it will not have to be reloaded every time. The constant packet-exchange will do that without any reload. This will, of course lead to high usability, high speed, interactivity and functionality.

The acronym stands for Asynchronous JavaScript and XML. Now let’s see how each of those parts affects the programming language:

* Since it does not interfere with page loading, Ajax is considered to be asynchronous.
* Ajax function calls are made in JavaScript.
* Using this technique, the data retrieved is most often formatted using XML.

You might be also interested to know that Ajax is derived from XMLHTTPRequest Object(and that is why I said that ajax was there even before web 2.0 came), and that it is a cross-platform technique that can be used on various operating systems, web browsers and even computer architectures. This means that you can use it on your Mac, or on a PC, on Windows or on Solaris and you can use almost any browser you like from Firefox to Amaya.

So What are the advantages of using Ajax?

* Bandwidth usage – The bandwidth usage is rather small since the HTML content is generated within the local browser and it only brings down several JavaScript calls and the actual data. Because of this, most websites constructed with Ajax will load relatively quicker than others. You can test this with multiple pages of data.
* Separation of style and function – Ajax encourages all programmers to be clear and specific in their codes by teaching them to clearly separate everything (formats, methods). This is a less specific benefit, since it mostly concerns the programmer, rather than the end-user, but it is still considered an advantage.

What about the disadvantages? One of these disadvantages is the downside of the first advantage listed above. Since the content in the page is created dynamically, it does not register with the browser history engine, therefore the Back button will sometimes bring a less desired result. Infact while using gmail, I faces serious problem with it. So though ajax may look cool but I feels usability and performance should not be compromised over ajax.

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