In this post I want to discuss how legacy projects evolve and discuss some ways to help projects to scale effectively. Many projects I see are organised in a way seemingly advocated by the frameworks they use. This approach is generally: src/ Command/ CleanOrdersCommand.php Controller/ PlaceOrderController.php Form/ SubmitCartForm.php Entity/ Order.php This is a good way to get started. Right!? You have a command, put it in the Command directory. You have a Doctrine Entity, put it in the Entity folder.