RIA technologies provide a framework for enterprises and independent software vendors (ISV) to create applications that have the look-and-feel of traditional installed applications, but with the deployment benefits of Web applications. RIAs are centrally managed and deployed, and are typically accessed via a Web browser.

RIAs differ from traditional Web applications in providing additional presentation and messaging options - just what Linux developers could use for desktop applications. RIA technology can be applied to classes of applications where HTML/JavaScript does not work well, such as those requiring intensive interactivity, the ability to manipulate large and/or real-time data sets, reliable and predictable messaging, or the ability to start and run disconnected from the network.

RIA technologies address the problems associated with the "last mile" of an application - from the middle-tier to end users' desktops. This tends to be the most expensive part of an application's development and deployment. In today's global, heterogeneous environments, enterprises must accommodate disparate end-user desktop environments (different operating systems, Web browser, etc.) and network access methods (dial-up, broadband, etc.).

RIA technologies are intended to handle those diverse environments, while providing a uniform framework upon which an enterprise developer can create an application without needing to research and test every possible combination of client platform and network type - that is part of the value-add of the RIA technology vendor. In addition, RIAs are deployed within application servers, typically J2EE, and can all interact with Web services, JDBC, and middle-tier business logic.

The RIA sector is already rich in choice. There are four basic architectural approaches that RIA companies use, each with its strengths and weaknesses for creating Web-based, enterprise-class GUI applications on Linux.

HTML/JavaScript/AJAX-Based
AJAX, which stands for Asynchronous JavaScript and XML, is a new name for a design model that has been around for years. AJAX provides a way for an HTML/JavaScript-based Web application to incrementally update the contents of the Web page by using the threading capability of the Web browser to make a background (asynchronous) request to the server for more data while allowing the user to continue interacting with the application. This makes traditional Web applications behave more like desktop applications by eliminating the "click-wait-refresh" problem, but also reduces browser compatibility due to differing JavaScript implementations. However, AJAX does not address enterprise requirements for server-initiated interactions with the client, improved reliability or offline access.

Flash-Based
RIA approaches that utilize Macromedia Flash enable developers to create visually rich UIs with multimedia content like transition effects and animation. Flash is most widely applicable for consumer-facing or data visualization applications like guided selling, guided forms, and dashboards. Besides being a proprietary technology, Flash relies on ActionScript, which limits its suitability for enterprise-class programming efforts. Most Flash-based applications also require each user to download and install the latest version of Flash (currently Flash 7).

Java-Based
Traditional Java offers a fundamental advantage of scripting-based approaches by virtue of being more amenable to enterprise-scale development and maintenance. But, as previously discussed, Java offers no role for the non-programmer and has little support for simplified GUI development. Finally, Java applications can have a large client footprint and/or require a specific Java Runtime Environment (JRE) version. Despite these concerns, enterprises often choose Java applet-based approaches for mission-critical applications where performance, maintainability and scalability are paramount.

.NET-Based
.NET offers an object-oriented programming model and can be used to create rich applications. However, .NET applications have a large client footprint and require that client systems have an appropriate Common Language Runtime (CLR) installed. Both these concerns make .NET-based RIAs a lackluster choice for enterprises looking to save on deployment costs. And for Linux desktops, a proprietary .NET solution does not compute.

The company I currently work for, Nexaweb Technologies, Inc., offers an RIA platform built on an open foundation of Java, XML, and Web standards. The Nexaweb Platform combines comprehensive, built-in services with a declarative GUI development model suitable for non-programmers. Nexaweb-enabled RIAs are inherently platform- and browser-neutral and provide centralized, no-install deployment.

Nexaweb has learned two valuable lessons about enterprise requirements from the Web and Visual Basic. First, enterprises want a way for non-developers to create and maintain screens using simple declarative (not code) mechanisms. Second, enterprises are looking for a component or plug-in framework that allows scarce senior developers to create reusable visual components that can be easily incorporated into the screen designs maintained by non-programmers.

The Time Is Now
SOA (service-oriented architectures) presents an opportunity for the Linux community to gain an advantage. As enterprises accelerate SOA initiatives, they seek to abstract many existing legacy systems into services that will allow them to eliminate older systems. Many of today's user-facing applications will need to be re-written to utilize these new systems.

This is the perfect opportunity for Linux to seize the high ground. If these new applications are written in a portable fashion, using RIA technologies, then enterprises will have the freedom to choose the right desktop operating systems based on their business requirements, not the system requirements of the application.

The benefits of this approach for enterprises are not just cost savings relative to the maintenance of their desktop systems; they will also benefit from increased agility by being able to respond more quickly to new market conditions with rapid development and deployment of enhanced versions of their applications.

Summary
As much as we'd like the whole world to just move to Linux, this is unlikely to happen. What is most appealing to enterprises about a Linux desktop is that it offers an alternative to Windows - not a replacement. Enterprises want choice and flexibility; the ability to choose based on business requirements versus application technology.

Therefore, in order to make inroads against the entrenched Windows desktops of today, Linux needs what Windows needed to displace UNIX: an application framework to make business application development faster and cheaper, especially by enabling non-developers to create GUI front ends.

However, because enterprises still remember those painful lessons about vendor lock-in that they relearned when they replaced UNIX with Windows, Linux GUI development frameworks need to support multi-platform applications. Finally, no alternative will dislodge today's GUI application that does not leverage the cost advantages of the Web for low-cost, universal reach and no-install deployment.

Rich Internet Application (RIA) platforms offer developers a way to bring the benefits of Web-based, enterprise-class applications to the Linux desktop. With enterprises rewriting many applications to implement SOAs, now is the time for the Linux community to capitalize on this opportunity to bring Linux to the desktop.

Resources

• www.bricklin.com/visicalc.htm
• www.iseran.com/Win32/FAQ/history.html
• www.li.org/linuxhistory.php
• www.w3.org/History.html
• www.developer.com/design/article.php/3526681