This started as a  Skype chat room conversation between my colleague Anatole Tartakovsky and myself, and I thought that it would be a good idea to invite more Flex developers to this discussion.

Having said this, I’d like to make it clear that over my career, I’ve been developing frameworks and truly respect people who are capable of creating frameworks, and Anatole has huge experience in this area as well.  Here we’re just questioning the need to create frameworks not for a general-purpose language like Java, but for a domain-specific framework like Flex.

This is our dialog with minor editing. Your input and feedback are greatly appreciated.

Yakov: Why do people design Flex frameworks as opposed to reusable components?  One of the framework is called Cairngorm, the other one is called PureMVC. I’m sure there is more. It seems to me that such frameworks are unnecessary overhead over well-designed Flex frameworks. Are there any benefits here? Why bother creating all these singleton-based bottlenecks?

Anatole: First of all, PureMVC seems to be more of an  ActionScript Framework. It is not specifically a Flex framework and concentrates on the task of creating a generic framework for low-level AS objects. Flex comes with “prebuilt suggestions” of how a model/view controller might work - and it offers lots of hooks throughout the data and UI classes that help implement MVC.

PureMVC is also "server-agnostic". Flex made the Java implementation of a distributed Model that can provide dynamics to the distributed Web applications very efficient. PureMVC is more about making apps in a more traditional way.

Cairngorm was started as “Micro – Architecture” – a set of patterns that allowed the solving of certain problems in the application design – like Model Locator or Commands – and certain applications. It never appealed to me as it had a number of assumptions that required more coding. At best you would use one or two pattern implementations from Cairngorm, but it’s much easier to rip out the part you need and adjust it to your liking.

Yakov:  I can appreciate the fact that design patterns are useful in general, because they may help developers deal with repeating patterns in software constructions such as Singleton, Mediator, Model-View-Controller and the like. But when I look at some of the third-party frameworks built on top of Flex, I keep asking myself the same question, "Why build a framework on top of a framework? Are there any benefits to introducing a middleman between an application's views and an already existing Flex framework?