IntelliJ Idea Flex and Actionscript 3 Workflow: [Part 1] Creating a Flex Project
I've been using IntelliJ Idea 9 quite a bit in both production and personal work lately. It is a great IDE, with lots of useful features. This is going to be a series of short screencasts that highlight the workflow in Idea for Flex/Actionscript development. The first is a quick introduction and how to set up a Flex project. If you have any questions or requests for future videos in the series please feel free to leave them in the comments.
direct link to the video (42mb QT)
Resources
IntelliJ IDEA EAP Download Page
Jesse Freeman's IDEA Workflow series on InsideRIA
Robotlegs, AS3-Signals and the SignalCommandMap Example
Robotlegs and AS3-Signals play really well together. Both apply solid object-oriented principles to accomplish their respective goals. Signals is extremely well suited for automated Dependency Injection. By combining Signals and Robotlegs you are able to eliminate the use of Flash Events in the framework layer of your application. Eliminating Events means eliminating the ambiguity that can accompany Events and their String registry based approach to the Observer pattern. Signals provides a strongly-typed object-oriented approach to this same pattern.
With the standard Robotlegs MVCS implementation you leverage the events provided by Actionscript 3 to communicate amongst the various actors of an application. From models and services dispatching notifications of their actions to triggering commands, events are a core piece of the implementation. To facilitate the use of Signals within MVCS it was necessary to create an extension to allow for Signals to be registered as Command triggers. This need spawned the SignalCommandMap utility.
The SignalCommandMap extends the normal MVCS context and creates a SignalContext. The SignalContext instantiates and provides access to the SignalCommandMap alongside the other maps that are standard to Robotlegs. The SignalCommandMap allows you to map Signal classes and instances to commands that will be executed when the Signal dispatch() method is called. The value objects that are passed in the dispatch are then injected into the command alongside any other mapped injections you have created.
Let's take a look at a simple example that makes use of the SignalCommandMap and discuss some of the underlying code to see how it works:
Robotlegs Image Gallery Example using AS3-Signals and the Presentation Model
Jason Crist posted a thought provoking request for his upcoming presentation comparing Robotlegs and Swiz. He's got a clever knack for stirring the framework ant pile and getting developers eyes off their IDEs long enough to discuss their passions. In this case the developers include Ben Clinkinbeard, Shaun Smith, Jesse Warden and myself.
These conversations are always good natured. While we work on (or use) "competing" frameworks there is always a sense of mutual respect. We like our tools but have obvious inclinations towards the projects that we've invested our hearts and souls into.
Ben Clinkinbeard has pointed out (several times!) that Robotlegs is all about extending the MVCS classes. My stock answer is that there is a clear separation between the framework and the concrete MVCS implementation. To paraphrase Ben, "Well show it to me then!"
All of the "official" Robotlegs examples are making use of the MVCS implementation. Why? Because it is solid, recognizable, and fairly easy to get one's head around. It provides a common ground for developers and a set architectural structure which is a huge advantage in any team environment. It is important to make the distinction between the framework and the MVCS implementation. What does that even mean? At the core, Robotlegs is a modular set of tools to provide a convenient mechanism for wiring applications. Robotlegs is not doing class reflection. Robotlegs is not an automated dependency injection solution. Robotlegs is an adapter to a dependency injection solution,by default the lightweight SwiftSuspenders library. Through a set of tools, namely the MediatorMap, CommandMap, ViewMap, and the injection adapter Robotlegs provides a robust starting place to begin coding your application.
The MVCS implementation is a set of base classes loosely modeled on PureMVC. At the heart of the implementation is the Context. The Context creates instances of the various mapping classes, the injection adapter, and gives the developer a centralized IEventDispatcher that can be used for messaging between application tiers.. The other three classes, Actor, Mediator, and Command, reduce boiler plate and provide convenient access to injected dependencies typically used in the the MVCS tiers.
What if you hate PureMVC, don't want to extend any framework classes, or generally just want to work in a different way outside of a prescribed MVCS architecture?
No problem.
Here's the deal. Robotlegs, the framework, is a set of interfaces. You can effectively do whatever you want with these interfaces. You can make use of the base concrete implementations of the core interfaces, use a class from the MVCS implementation, implement your own concrete classes based on the framework core, bring in other libraries or any combination you can think of. In terms of a framework, Robotlegs can be whatever you want/need it to be.
Man Joel, that was a long intro. Where's the freaking code??!?
Continuous Scrolling Thumbnail Component for Flex
This post continues to be the most popular on this space after a year and a half. I've never been particularly fond of the implmenetation. Tightly coupled to very specific data sets and not really anything like a Flex component. It is setup more like an application (because it was pulled out of an application and generalized).
I've finally found the opportunity to rewrite the continuous scrolling thumbnail view portion of the slideshow and I am much happier with the results. Now, instead of resembling an application it is structured like a standard Flex 3 List based component. You supply it with a dataProvider and an itemRenderer (IListItemRenderer) and it acts as you would expect it to.
This approach is much nicer, as the data is cleanly decoupled from the component implementation and it opens up the doors for reuse.
The code is available on Github. If you have any suggestions or would like to add to the component, fork it and let me know!
Robotlegs MVCS: Walkthrough of an AIR Twitter Client
Here is the "completed" project on Github.
This is a roughly 25 minute walkthrough of wiring together a Twitter client using the Robotlegs AS3 Micro-Architecture MVCS implementation. It covers setting up the context, using commands, mediating composite view component, granular view component mediation, and retrieving data from a service.
Apologies in advance for the ambient noise. 4 kids, 2 dogs, and a busy wife does not make the perfect sound booth 
I am considering expanding on this example and creating a start to finish video series creating a full Twitter client with Robotlegs. This would cover the actual component building, wiring everything together, working with data models (local storage, etc), and refining the application to use the advanced features available with the Twitter API using TDD the whole time for development. Is this something that you'd be interested in?
Robotlegs IoC/DI Flex Framework Examples Updated
Live demos are available on robotlegs.org here
Acme Widget Factory:
The Acme Widget Factory is modular example and deals with loading multiple modules into a shell and communicating between those modules. The shell and each module has its own context.
Lazy Stack:
Lazy Stack is an example of deferred instantiation of Flex components, and how this is handled by the Robotlegs framework.
Wheres Window:
Where's Window is a simple example to show how to mediate and communicate between a set of instances of the same view component that have individual mediators. In this case, the view components are windows in an AIR application. This uses a proxy to register and manage the currently open unique windows. I am going to write a more detailed breakdown of this particular example soon.
The Elevator Pitch
Robotlegs is an IoC/DI container that is modeled on the PureMVC application structure. It is designed to be MVCS, model-view-controller-service, providing metadata dependency injection across these layers. While following the well organized approach of PureMVC, it eliminates the use of framework singletons and takes full advantage of the Flash Platform to keep the dreaded boiler plate code to a minimum. Eliminating these singletons makes unit testing and TDD much easier, which can be a real struggle when trying to isolate classes for testing where these singleton dependencies exist. Robotlegs is fast, clean, and perhaps more importantly fun to work with. There is a smorgasbord of architectural frameworks available for Flex/AS3, but Robotlegs is worth a look even if you are sick of looking at architectural frameworks.
Unit Testing: IoC/DI, Robotlegs and FlexUnit 4
I've been reviewing the various IoC containers available for Flex/Actionscript. One of the benefits of IoC and DI is that it greatly facilitates unit testing. By injecting our dependencies into our applications actors, we are effectively isolating them from the other classes that make the application function. "So what?"
In computer programming, unit testing is a software verification and validation method in which a programmer tests that individual units of source code are fit for use. A unit is the smallest testable part of an application. In procedural programming a unit may be an individual program, function, procedure, etc., while in object-oriented programming, the smallest unit is a class, which may belong to a base/super class, abstract class or derived/child class.
Ideally, each test case is independent from the others: substitutes like method stubs, mock objects, fakes and test harnesses can be used to assist testing a module in isolation. Unit tests are typically written and run by software developers to ensure that code meets its design and behaves as intended. Its implementation can vary from being very manual (pencil and paper) to being formalized as part of build automation. -wikipedia unit testing entry
To effectively unit test classes, we want them to be as isolated as possible. The class needs to stand on its own and have its functionality vetted to ensure that it behaves as expected. When we start to test how our classes behave together, we have entered the land of integration testing. Integration testing is a worthwhile pursuit also, but before we get to that point, we really want to ensure that our classes are solid by themselves.
Using the example in this Robotlegs Image Gallery demonstration, we are going to test a couple of the classes that make up the application. The demo isn't complex. It has a very simple model, a single service, and just a few views. In fact, it might even seem like a waste of time to unit test a simple example such as this, but the concepts are applicable to larger applications where the benefits of this type of testing really start to pay off.
FlexUnit 4 is the framework that is used here. It provides very handy asynchronous testing, meta data support, and a whole bucket of stellar features that I won't even begin to scratch the surface of. FlexUnit 4 also comes with a graphical testrunner interface:
Robotlegs AS3: A Dependency Injection Driven MVCS Framework for Flash/Flex – Inspired by PureMVC
The quest for a Dependency Injection container continues. The most recent stop on this exploration of the available options has been Robotlegs. Robotlegs AS3 is a DI driven MVCS framework for Flash/Flex inspired by PureMVC. Being a huge fan of PureMVC, this caught my attention immediately. Robotlegs professes to be a framework like PureMVC, but without all the Singeltons, Service Locators, casting and boiler plate we have all come to love. Better yet, it delivers on these claims.
Source for this demo available on github...
Inversion of Control and Dependency Injection with Flex using the Parsley Application Framework – Part 2
This is the second part in a series exploring Inversion of Control and Dependency Injection containers available for Flex. In the first part of the series we discussed what IoC and DI are and how they can benefit our applications. In this part, we will explore the Parsley IoC Container through a simple image gallery application.
Here's the source on github...
Piping the Machine: PureMVC Multicore with Pipes and the Finite State Machine (FSM)
This is going to be a walkthrough of making use of PureMVC Multicore (AS3). To help in building a PureMVC Multicore application, we are going to make use of the StateMachine utility for initial setup and configuration as well as the Pipes utility for communication between cores.
