Igor Wiedler has a new post to his site today talking about scaling Silex-based applications (a microframework based on Symfony components) and using it for more than just the basic applications.
One common misconception about silex and microframeworks in general is that they are only suited for small, simple apps, APIs and prototyping. Of course, those use cases are the main selling point, but they are by no means the limit of what is possible.
He shares some code that's the common "first steps" for someone using the framework, but points out a better way - moving your controller handling out into separate files instead. With a built-in feature of Silex, you can specify the "path" to another class file that will handle the request and return the response back to the main app. He also suggests extracting even more of the functionality out into "service" classes to handle the processing, cleaning up the controllers even more. He finishes off the post with a brief comparison between Silex and a full Symfony2 application, noting that Silex is a bit more "free form" when it comes to structure where Symfony2 apps are pretty well defined and have their conventions.