The DHTML/JavaScript approach fits well with existing HTML Web applications. It is natural for an existing HTML developer to write JavaScript, and the least expensive way of adding interactivity to an existing HTML application. In general, this approach requires the download of (potentially large) JavaScript libraries to compensate for the differing capabilities of the client browsers. The resulting applications are as rich as the underlying browser will allow. This approach can be problematic in large scale business applications due to difficulties developing and maintaining JavaScript, as well as performance/functionality limitations of DHTML.
The Flash-based approach is good for applications that require a "sexy" look and feel. It is a natural option for graphics designers. Flash enables developers to create very rich user interfaces, given Flash's heritage as a "movie engine." To date, Macromedia has targeted Flash for three use cases in the context of applications: guided selling, guided forms, and dashboards—primarily consumer facing or data visualization applications. Flash applications can access Java and .NET objects running on the server asynchronously. The major limitations of this approach are ActionScript and the limited capability of the Flash engine. ActionScript is a proprietary scripting language developed by Macromedia. It is easier to do scripting than programming for simple tasks, but developing and maintaining many scripts is difficult and expensive for more complex applications. Flash is not an industrial-strength virtual machine like JVM or .NET CLR; as a result, there are functionality and performance limitations for Flash-based applications.
There is no doubt that all three approaches are viable and each has success stories to prove it. However, choosing the wrong approach for the job also can be devastating.
Taking AJAX a Step Further
AJAX addresses some of the problems of the Web today, but there are still significant problems that AJAX does not address. For example, how do you make Web applications offline available? How do you enable server-initiated communications? How do you guarantee consistent performance, as well as reliability for Web applications, given that HTTP is not reliable and Internet performance is inherently limited by network conditions?
AJAX itself is not the destiny, but rather a leading indicator of how the Web application model is evolving. All of the above problems must be addressed for the Web to become a truly available, reliable, and performance infrastructure for software applications.
Conclusion
AJAX represents a generic application model that would enable more interactive, more responsive, and smarter Web applications. AJAX is not tied to a particular programming language, data format, or network object and is defined by two core attributes: partial screen update and asynchronous communication. There are three approaches to build and deploy AJAX applications: DHTML/JavaScript (Asynchronous JavaScript + XML), Java (Asynchronous Java + XML), and Flash (Asynchronous ActionScript + SWF). Each approach has its strengthes and weaknesses; as such, customers should evaluate and choose carefully.
Endnote
1. http://www.adaptivepath.com/publications/essays/archives/000385.php
About the Author
Coach K. Wei, Founder and CTO, Nexaweb Technologies combines in-depth IT industry expertise with extensive education and research experience at MIT to provide the vision for Nexaweb. He founded Nexaweb in 2000 and served as CEO until summer 2003. At Nexaweb, Coach is responsible for driving technology innovation and business direction that successfully enables enterprises to securely migrate large-scale enterprise applications to the Web — commonly known today as Rich Internet Applications (RIAs).
Before founding Nexaweb, Coach architected and designed enterprise software for managing storage networks at EMC Corporation. As a graduate researcher at MIT, Coach developed software and hardware systems for non-destructive evaluation as well as signal/image processing algorithms. Coach was a finalist in the 1999 MIT $50K entrepreneurship competition and is the holder of several US Patents. He holds an MS in Information Technology from MIT.
Coach has published numerous articles on various topics including AJAX, J2EE and .NET, RIA development, XML, signal/image processing, composite materials, ultrasonic imaging and software. Additionally, he has spoken at leading industry events, such as JavaOne and Web Services Edge. You can contract Coach Wei at cwei@nexaweb.com
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