AJAX is a new term, but it referes to a collection of technologies that have been complete since around 2004. It’s use has been popularized through the groundbreaking work of Microsoft, Google, and smaller firms such as AdaptivePath, who coined the term. AJAX adds the capability of getting new data from a server once a web page has been generated, in hopes of reducing screen refresh, lowering bandwidth utilization; additionally, developers hope to increase user interactivity of web based applications to the level of a regular desktop application. All of this has come at a cost though, including increased complexity, reduced accessibility, and new security threats.

Literature on AJAX

Little academic literature that focuses on AJAX exists, as most of its components have been the result of previous academic and industry work. Much of the literature that exists is in the form of white papers, recommendations, and industry practitioner guidelines. One of the first such guidelines comes from Microsoft, where they discuss using ASP to do server callbacks after the web page has been generated[1]. Microsoft did not coin the usage of the term AJAX; that was done well by Garrett et al. at Adaptive Path, who wrote the root article that contributed to common understanding of how AJAX applications are to be structured, and how they differ from regular web applications[2]. If you’re interested in determining whether AJAX is in fact a model you should be pursuing in developing your own application, there is no shortage of expert opinion on the pros and cons of the technology [3].

Specifically in terms of security concerns, which are always heightened when developing web-accessible applications, there are a whole new set of things to think about [4]. Good industry examples are abound. A great collection of these examples is Ajaxian[5], a website run by seasoned web developers. The components that make up AJAX are not anything that web developers have not used before. The Wikipedia entry on AJAX programming [6] defines these components, and gives context to their use: JavaScript, XMLHttpRequest Class in JavaSctipt, XML as a data transport, and the Document Object Model (DOM) for manipulation of the static web page. Historical information on how AJAX got to the point it did points to an evolution from DHTML, as well as Microsoft’s work in Remote Scripting [6].

For guidance on implementing AJAX within your own work, Apple’s Developer Connection entries [7] are thorough and explore issues related to browser incompatibility. Though, in order to stay on top of all of the browser related issues, a developer can rely on a variety of frameworks and libraries that are kept up to date with functionality and security updates:

• Dojo. An open-source framework being supported by IBM and Sun.
  http://dojotoolkit.org/
• Atlas. The Microsoft AJAX framework that employs ASP.
  http://ajax.asp.net/Default.aspx
• Google Web Toolkit. Googles official AJAX toolkit (as seen in Google Mail and Google Maps).
  http://code.google.com/webtoolkit/
• Prototype. A decidedly simpler library than any of the above.
  http://prototype.conio.net/

You can download my presentation here: Presentation: Ajax – A new hero for the Web?. Some images used in the presentation are sourced from [2].

References

1. Esposito, D. “Cutting Edge: Script Callbacks in ASP.NET.” MSDN Magazine. (August 2004).
   http://msdn.microsoft.com/msdnmag/issues/04/08/CuttingEdge/
2. Garrett, JJ. “Ajax: A New Approach to Web Applications.” Adaptive Path, LLC. (February 2005).
   http://www.adaptivepath.com/publications/essays/archives/000385.php
3. Downes J, Walker J. “Pros and Cons of using Ajax in a CMS.” CMS Watch. (February 2006).
   http://www.cmswatch.com/Feature/143-Direct-Web-Remoting
4. Twynham, S. “AJAX Security.” IT-Observer. (February 2006).
   http://www.it-observer.com/articles/1062/ajax_security
5. Ajaxian. (October 2006) http://ajaxian.com/
6. Wikipedia contributors, “Ajax (programming),” Wikipedia, The Free Encyclopedia. (November 1, 2006). http://en.wikipedia.org/wiki/Ajax_%28programming%29
7. Apple Computer, Inc. “Dynamic HTML and XML: The XMLHttpRequest Object.” Apple Developer Connection. (June 2005).
   http://developer.apple.com/internet/webcontent/xmlhttpreq.html