Symfony2 Videos Playlist
What is Symfony2?
When I ask people what Symfony2 is for them, most of them say something along the lines of: Symfony2 is a full-stack web framework written in PHP. Some also add that this is an MVC framework. And some others add that this is a decoupled framework. This is all fine and correct. But my definition is a bit different. Let me tell you what it is and why I think it matters.
Symfony2 is really about two different things.
First, Symfony2 is a reusable set of standalone, decoupled, and cohesive PHP components that solve common web development problems.
Then, based on these components, Symfony2 is also a full-stack web framework.
Depending on your project and depending on your needs, you can either pick and choose some of the Symfony2 components and start your project with them, or you can use the full-stack framework and benefit from the tight integration it provides out of the box. And choosing between the two different approaches is really up to you.
Is Symfony2 an MVC framework?
If you look around, every single framework seems to implement the MVC pattern. And most of them are advertised as MVC frameworks... but not Symfony2. Have a look at the documentation, and you will see that the MVC pattern is only mentioned once or twice, but Symfony2 is never defined as being an MVC framework. Why?
Because I really don't care whether Symfony2 is MVC or not. Probably because the MVC word is so overloaded and because nobody implements exactly the same MVC pattern anyway. The separation of concerns is all I care about. And if you like to call Symfony2 an MVC framework, then you should know that Symfony2 is really about providing the tools for the Controller part, the View part, but not the Model part. It's up to you to create your model by hand or use any other tool, like an ORM. Of course, tight integration exists for the most well known ORMs like Doctrine2 and Propel; but they are optional dependencies. The Symfony2 core features do not and will never rely on any ORM.
I don't like MVC because that's not how the web works. Symfony2 is an HTTP framework; it is a Request/Response framework. That's the big deal. The fundamental principles of Symfony2 are centered around the HTTP specification.
I don't like MVC because the web has evolved a lot in the recent years and some projects are much different than projects we had some years ago. Sometimes, you just need a way to create a REST API. Sometimes, the logic is mostly in the browser and the server is just used to serve data (think backbone.js for instance). And for these projects, you don't need an MVC framework. You need something that handles a Request and returns a Response. You need a framework that implements the HTTP specification. HTTP streaming is yet another example that does not fit well with the MVC pattern.