by Amila Mendis

In the previous article, I talked about how the architecture of the web applications changed by the time and according to the requirements of the people.

Now let’s talk about the Rich Internet Application in more details.

Rich Internet Applications can be defined as “a cross between Web applications and traditional desktop applications, transferring some of the processing to a Web client and keeping (some of) the processing on the application server”. Traditional web applications keep all the processing instructions in the server side and client side is used only for presentations. There are several features that can be identified in the Rich Internet Applications which cannot be seen in the traditional web applications. They can be mentioned as follows.

·     Responsiveness and interactivity

In RIA most of the processes are done in the client side that reduces the network traffic and that provides a faster response as the application leverages the client CPU. And these applications are communicating with the server asynchronously, when a button is clicked only the corresponding part of the application is reloaded not the whole page. This feature provides a continuous reference to the users as they are not distracted by the changing interface.

·     Rich user Interface

Rich Internet applications provide a user friendly rich interface to the user as the normal desktop applications provides. Those interfaces are consists of graphical elements, audio, video and other visual effects.

·     RIA capitalizes on the broad reach of the Internet, allowing application to be assessed any time any where by any authorized user.

·     Real time communication

Rich Internet Applications allows users to communicate and share information on the Internet through real time communication channels such as messenger, audio and video conferences etc.

Technology behind RIA

Rich Internet Application is a collection of technologies that are worked together in order to

build Rich Internet Applications. The main contenders are Adobe Flash, java applets and the

collection of web technologies called Ajax.

Java: Java is a programming language that supports server side programming and client side

programming. So java can be used to create any kind of a rich client application. Java is now several years old and has very comprehensive support for building form-based UIs. In addition to the user interface components found in the Java Foundation Classes (JFC/Swing), developers can also use the Standard Widget Toolkit (SWT) from the Eclipse Project and a raft of other third-party toolkits. Java 2D package can be used for graphics and also java supports XML also. But java can be more complex in programming because even a simple form or graphic needs dozens lines of codes.

Flash and Flex: Flash is a mature commercial product for bringing interactive graphics to Web pages. It has recently been upgraded to include features for building forms-style applications. Flash has got ability to build very interactive animations. Flash uses the scripting language called Action Scripts which is more similar to the JavaScript. Flex is a collection of technologies released by the Adobe for development and deployment of cross platform rich internet application. Flex adds the XML language to the Flash so the user interfaces can be compiled and rendered o the fly by the flash player which is used to represent the Flash contents in the browser. Flex proves the workflow and the programming model that is familiar to the

programmers. MXML, an XML-based markup language, offers a way to build and lay out graphic user interfaces and Action Script is used for the programming part.

Ajax: Ajax stands for Asynchronous JavaScript and XML which is a technology that combines other technologies such as JavaScript, HTML and XML. Ajax based web applications combines.

·   XHTML and CSS standards based presentation.

·   Interaction with the page through the DOM

·   Data interchange with XML and XSLT

·   Asynchronous data retrieval with XMLHttpRequest.

·   JavaScript to tie it all together

In Ajax the client communicate with the server asynchronously. There for no page reload is needed. Because page reloading is the main drawback in the traditional web applications. Ajax technology brings the solution for that. Ajax uses the XMLHttpRequest object to communicate with the server. Specialty of the Ajax is it can be integrated with any kind of a language such as java, PHP, Asp etc. JavaScript combines all the related technologies in order to work as a whole. Therefore no matter what programming language is used, Ajax can be used in the application. That is the main advantage of the Ajax. Other than these basic technologies XUL which is a

XML based UI language also used in the developing Rich Internet Applications.