The Use of Ajax Programming in cnn july 7, 2008

William L. Waldock Jr.

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  In many cases, the pages on a website consist of much content that is common between them. Using traditional methods, that content would have to be reloaded on every request. However, using Ajax, a web application can request only the content that needs to be updated, thus reducing the number of server requests.
  
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  Because only sections of pages need to be reloaded, Ajax improves usability of web applications, giving users the feeling that changes are happening instantaneously.
  
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  The use of Ajax can reduce connections to the server, since scripts and style sheets only have to be requested once.
  

Disadvantages

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  Dynamically created pages do not register themselves with the browser's history engine, so clicking the browser's "back" button would not return the user to an earlier state of the Ajax-enabled page, but would instead return them to the last page visited before it. Workarounds include the use of invisible IFrames to trigger changes in the browser's history.
  
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  Dynamic Web page updates also make it difficult for a user to bookmark a particular state of the application. Solutions to this problem exist, many of which use the URL fragment identifier (the portion of a URL after the '#') to keep track of, and allow users to return to, the application in a given state.
  
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  Because most web crawlers do not execute JavaScript code, web applications should provide an alternative means of accessing the content that would normally be retrieved with Ajax, to allow search engines to index it.
  
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  Any user whose browser does not support Ajax or JavaScript, or simply has JavaScript disabled, will not be able to use its functionality. Similarly, devices such as mobile phones, PDAs, and screen readers may not have support for JavaScript or the XMLHttpRequest object. Also, screen readers that are able to use Ajax may not properly read the dynamically generated content.
  
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  The same origin policy prevents Ajax from being used across domains, although the W3C has a draft that would enable this functionality.
  
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  The number of HTTP requests to a web server can increase considerably, causing an increase in server load.
  

The use of AJAX programming could be really special for the CNN application. One of the leading criticisms of online news content the lack of a “stumble upon” effect that you have in a newspaper, i.e. you need to seek out almost all stories. In a news paper you have to browse various stories you may not seek out as you flip through the pages looking at various articles. With AJAX you could almost create a newspaper on the monitor that people can drag and pull. If you think about the evolution of monitors to a multi-touch platform you can see how AJAX programming in a news source could alone be worth switching from the incumbent news sources. Another cool thing to think about would be some sort of partnership with Apple since they are leading the way in multi-touch platforms. This could turn into Apply installing our web app on all their phones and new computers, as well as blackberry, which is closely following suit with a multi-touch screen in a mobile phone. I think this type of formatting could really lend itself to mobile applications since they are so hard to view on a small screen, being able to zoom and almost throw the news paper around on the screen could prove to be an awesome feature. The range of options that an AJAX style of programming would open up as far as presenting content is pretty awesome. It also provides a huge competitive advantage for the “early adoption” crowd and gets them to try out the site.