Rich Internet Application becomes the popular term nowadays. RIA has the features and functionalities similiar with Desktop Application. It fulfills the limitations of typical application:

- Stateful data: Http is a stateless protocol, it can not maintain the status across pages while navigation at client side

- Network efficiency: Almost data proccessing belong to server side (client side is responsible for validating data and tune message format only). It can causes the bottleneck at server side because the client try to send many requests to server

- Offline: most of current applications can not run offline and synchronize data with server when connect to Internet. It limits user only run services while online. Thought there are some efforts (one comes from Google Gear) to make the application can run offline but it is hard to use only scripting language to make the application can run offline totally.

- Look and feel: web application support users can custom look and feel via CSS. CSS is a powerful tool for web designer can change color, font etc but it is hard and require deep experience to make Web UI looks similar desktop application

- Browsers: web application can run differently in different browsers, write a portable java script is not an easy tasks of any developers. Whenver the new browser release, they must re-test to make sure their application can run on new browser.

Client in RIA plays as thick/rich client not thin client in traditional web application. It shares the workload with servers, it can handle business rules, cache data in client side and run without server (synchronize data later). It is not doubt that RIA will becomes more popular in future and all web applications in future will be RIA.

There are four main technologies support RIA now; They are ajax (GWT), Flash (Open Laszlo, Flex), Java (JavaFX) and Microsoft (Silverlight). Each technology has advantages and disadvantage, it is depended to developers choose the right platforms meet their needs:

- Ajax: There are more than 200 ajax frameworks now!!! Ajax provide the capacity to enhance existing web applications by asynchronous invocation to save network bandwidth. Many ajax libraries such as yahoo UI, dojo provide web designers more tools to make web application theme looks like desktop. However, offline still be hard to implement in ajax world also there is no visual design tool that help designers drag-drop UI controls similar in Desktop Application.

- Flash: the most mature RIA platform today. At the beggining, Flash just be the platform to run annimation with 3D-effects but it becomes the powerful RIA platform now. With powerful programming language is ActionScript 3.0 and Flash Runtime is installed almost PCs in the world (and Flash Runtime size is smaller than JRE or Silverlight) that makes Flash platform is ready for RIA right now.

- Java: Applet is the first technology that help developers can build RIA though the RIA term occurs after the first Applet version. The JRE's size is too big for download and Sun JVM is not included in OS distribution is the main root causes make Applet is a failure besides L&F of Applet application is not good enough also be another reason. Java Web Start also be next failure due to the same reason. I doubt the success of the new RIA platform of Java is JavaFX. It is clear that JavaFX still be unmature. No book about JavaFX, several articles teach how to use FX to build desktop application. JavaFX is the one for Java lover examine the new platforms, developing the critical applications base on JavaFX should be waited for a long time (at least 1 year later)

- Microsoft: The monster of software industry come to RIA world rather late. But the future of Silverlight is promising and there may be the debate in future between Silverlight (Flash killer?) and Flash. Though the new Silverligh is at alpha stage but their roadmap is excellent. With .NET framework is installed in all Windows PC, the Silverlight runtime could be installed into IE default in future, it is no doubt that users use Microsoft products have a ready client environment to run RIA and utilize the powerful of .NET framework at client side.

In the next post, I will evaluate some platforms to develop RIA they are OpenLaszlo, ZK, Silverlight, Flex and the platform we decide the build our RIA on it.