Datasheet

Chapter 1: Introducing Cairngorm

ModelLocator

The ModelLocator serves as a central repository for shared application data. It allows components of the

application to have access to the same set of data to ensure synchronization. Additionally, through Flex ’ s

data binding mechanism, it notifies views of any changes to the data so that the views can update

themselves to reflect those changes.

ServiceLocator

Most RIA applications require communication with a backend system. This communication with the

backend is generally accomplished with one of the remoting classes, such as HTTPService, WebService,

or RemoteObject. The ServiceLocator provides a centralized location for access and sharing such services

so that they do not have to be declared in each component that needs to access the service.

Commands

Command classes are triggered by Cairngorm event classes to trigger business logic and update the

ModelLocator. In standard Cairngorm practice only a command should ever update the ModelLocator.

Events

Event classes are used to trigger command classes and pass along any data they require.

FrontController

The FrontController provides a centralized location for defining how Cairngorm events are handled.

This class registers event - command relationships and triggers the registered command for a given event

when that event is fired.

Value Objects

Value objects are classes that represent conceptually related sets of data. Value objects contain public

properties that represent the individual pieces of data being represented. They are commonly used to

represent data in views by binding to their properties, and to transfer related sets of data between classes

in the application and the server.

Delegates

Delegates are classes responsible for accessing remote services. They serve as proxy objects that take care of

the details of accessing a particular service and return the data from the service via responder functions.

Basic Cairngorm Logic Flow

Now that you have a sense of the major components that make up Cairngorm, the following is a broad

overview of how logic is implemented in a Cairngorm application.

The basic chain of events in a Cairngorm application can be seen in Figure 1 - 1.

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