Part 3 of this series explained how to construct the user interface of an enterprise rich Internet application (RIA) using MXML and ActionScript. Most importantly, it explored an area of application development where Cairngorm imposes itself least—and where it provides the greatest degree of flexibility. After all, it is the user experience that differentiates RIAs from traditional web applications, and any attempt to impose a structure on constructing the view limits the richness of the application.

If an RIA is a conversation between man and machine, then Cairngorm is the interpreter. So far, we have described how Cairngorm enables the machine to talk to the user as it renders the application's state in a dynamic, visual way. Now consider the more important aspect of communication: listening (rather than talking). In this article, we explore the design patterns that Cairngorm uses to listen to the user. we describe how Cairngorm understands user gestures to determine what the user wishes to do in the application. As with Parts 2 and 3, this article will reference samples from the Cairngorm Store application.

In the Cairngorm Store, a user can browse a product catalog, select products, view details on selected products, drag products into a shopping cart, and purchase the products through a checkout process. Cairngorm encourages you to breathe interactivity into rich and immersive experiences, and it enables your application to respond to your users' every gesture, whether through a mouse click or keyboard stroke.

This article explores the most fundamental and innovative patterns of the Cairngorm microarchitecture: the Front Controller, Event Broadcaster, and Command patterns. Understanding how they collaborate will help you to rapidly and consistently develop RIAs with Flex.

• Part 1: Introducing Cairngorm
• Part 2: Keeping state on the client
• Part 3: Architecting the view
• Part 4: Feature-driven development
• Part 5: Server-side integration
• Part 6: Rapid and consistent development with Cairngorm and Flex

Requirements

In order to make the most of this series, you need the following software and files:

Flex Builder 3

• Try
• Buy

Cairngorm version 2.2

• Download Cairngorm version 2.2

Cairngorm Store

Throughout the series you will find references to code taken from an e-commerce application named Cairngorm Store. You may use this sample application to gain a better understanding of Cairngorm, but please consider it only as a guide. Adobe is not responsible for maintaining the Cairngorm Store application.

• Download Cairngorm Store (J2EE Container version)
• Download Cairngorm Store (non J2EE Container version)

Prerequisites

Read the previous articles in the series, starting with Developing Flex RIAs with Cairngorm Microarchitecture – Part 1: Introducing Cairngorm before reading Part 4.

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