Rich Internet Applications

From the first day that a non-technical end user started using a custom web application developers and users alike have been pining for web applications that behave like traditional client side desktop applications. The high volume sites out there like Dell.com, Amazon.com, Google, etc all stick to basic standard web application navigation and behaviors. They use links for navigation and simple lists for order items on a screen. Most of the sizzle is just animation or video displayed within the Adobe flash player. There is a reason for this… these techniques work and work well for what the web provides.

Still, users and developers are constantly trying to bring more desktop application style behavior to the web. This effort has resulted in a class of web applications known has Rich Internet Applications (RIA). Google made this popular by using existing technologies that have been available in the major internet browsers for a long time but just hadn't been utilized. Web developers shied away from these because they had been bit by browser rendering inconsistencies for so long that they avoided it to make their life simpler. Over time the common browsers got more mature and this functionality became more consistent and sites like Google started taking advantage of it.

The technique Google and others began using was given the name AJAX. It is a combination of Javascript , XML, and Asynchronous calls from the browser back to a url or service on a server to update and get new data. Multiple Javascript libraries ( such as Dojo and Prototype ) became popular because they provided a common framework for presenting desktop like behavior such as drag and drop and other visual effects in a web page.

Another technique for providing RIA's is found in the Google Web Toolkit (GWT) and OpenLazlo. These two tools follow the same basic architecture. They created a Java framework that contains User Interface Components with behaviors that mimic the behavior of their Javascript based framework that gets deployed in a web application. To develop in these environments all the user interface functionality is coded and tested using namespaces and components in the Java framework in a Java IDE like Eclipse. Then when the application is ready to deploy a utility supplied in the toolkit converts the source to Javascript that utilizes the Javascript version of the same user interface components. The Javascript is what gets deployed to the web server.

The third technique for providing RIA's consists of having a runtime component that runs as a plug in to the browser on the client. The three more popular tools for doing this are Adobe Flex which utilizes the Adobe Flash player, Microsoft's Silverlight which uses the Silverlight plug in, and Curl which utilizes the Curl RTE. Also a fourth option is the new JavaFX which utilizes the java runtime plugin for the browser in the same fashion that Java Applets would execute in a web page.

All four of these solutions have the advantage that development can occur in an IDE much in the same fashion as a desktop application would be developed. They all provide support for multimedia as well as straight UI and forms development. Some of these solutions (Adobe Flex, Curl, JavaFX) provide the capability of running the applications from a server or they can also run from the desktop. All of these solutions provide the capability to interact via Javascript with other elements on a web page.

Deciding which one of these is right for your RIA can depend on multiple elements. If you are a Microsoft shop then Silverlight is going to be the way to go because if you have Visual Studio 2008 or plan to upgrade soon you have all the tools you need. If you already work artists and web designers that use Adobe products you may want to lean towards Adobe Flex because the interchange of graphics between the designers and developers will be easier. If you are a Java shop you have multiple options. GWT, OpenLazlo, and JavaFX are all Java centric and may be an easier transition.

If you want your web application to stand on its own and not require any kind of a runtime then GWT, OpenLazlo, or straight Ajax using a framework like Dojo or Prototype may be the way to go. Before you get too hung up on requiring a runtime though consider that most people have already accepted the Adobe Flash player plug in their browser because so many sites use it for multimedia functionality. Microsoft through their automatic updates are going to make sure that Silverlight is on everyone's Windows machine so chances are they won't have to install it to view your web site. Also these concerns are only if you have an Internet facing site, if you are considering these for an Intranet site where the desktop environments are controlled then requiring a run time plug in shouldn't be an issue.

There are a couple of software development guidelines that should be followed when using RIA's regardless of which one is chosen. The first key thing is that only use the tool (Ajax, GWT, Adobe Flex, Silverlight, etc) for User Interface. I can't emphasize this enough. ALL business logic should reside back on the server and be accessed via services calls. Do not try and put all your application code in Javascript, ActionScript(Adobe), Silverlight (C# or VB.Net). I have seen many RIA projects fail because they try and put the whole application in the RIA environment and just make data CRUD style calls back to the server. The RIA solution should be used for seamless, flashy, or sizzle type user interface effects or functionality and not for handling invoice transaction logic.

Another key factor is to keep the User Interface side of the code separated by visual components and artifacts and coding logic. Adobe Flex and Silverlight do a nice job of this just based on how these tools are architected. If you are using an AJAX type solution then that separation is done totally through development project management and not necessarily inherent in the tool.

So what are you waiting for try one of the technologies mentioned above and code away.