Cairngorm. In a brief!

Here's a link straight from the horse's mouth as they say!

The Cairngorm - micro-architecture as a composition of design patterns, addresses three key areas that Adobe Consulting has long recommended as best-practices for their customers and partners:

- Handling user gestures on the client
- Encapsulating business logic and server interactions
- Managing state on the client and representing this state to the user interface

There are four key benefits that Cairngorm provides:

- Maintaining state on the client
- Architecting the user experience
- Implementing feature-driven development
- Invoking server-side services

Important Components

Following are the important components of Cairngorm:

A) Model - holds the data and the state.

Generally we create a ModelLocator as a composition class consisting of public static getInstance method returning a static singleton reference to itself. all the model objects are stored and refered to from this ModelLocator handle.

B) View - render data and watch the data changes with bindings. Views talk to controller with events.

C) Control - Control layer is implemented as following sub parts

a) Commands - implement execute method that crunches business logic and make use of the model. Create Responder by passing Remote Service Result Handlers and pass the responder to appropriate delegate in constructors. Then invoke asynchronous remote service operations on delegates.(implements com.adobe.cairngorm.control.ICommand).

Register the commands to Cairngorm framework in Front Controller by using addCommand(eventType, commandClass) method.

b) Delegates - Are like proxies for business service APIs. E.g. UserDelegate provides routing to Login, Logout, Registration. OrderDelegate provides Create, Update or Delete order.

To implement a delegate's service method, make use of ServiceLocator. Invoke the appropriate service and attach the responder to the async token of the service operation called.

c) Events - Make use of business events to trigger commands. Typically create one event for each command. Extend com.adobe.cairngorm.events.Event class.

d) Front Controller - Registry of Event to Command mapping. Intercepts dispatched business events and routes them to appropriate commands extends com.adobe.cairngorm.control.FrontController

e) Service Locator - Base your service locator mxml component on Cairngorm ServiceLocator (extend the com.adobe.cairngorm.business.ServiceLocator). Add service tags with id. In your delegate obtain reference as follows

var service:HTTPService=__locator.getHTTPService("UserService");
var token: AsyncToken = service.operation();
token.addResponder(responder);

General Benefits

- maintenance is easier
- debugging is easier
- feature additions and/or changes are easier
- automated testing of business logic and data access is easier
- using mock data-services is easier