The understanding of Heroku won't be complete without understanding the methodology that is an outcome of the evolution of the Heroku platform. The Twelve-Factor App (TFA) methodology underlines certain key design principles that the developers should use to develop truly powerful SaaS web apps. The methodology is a result of solidifying the best practices for developing web apps on a PaaS such as Heroku, which architecturally focuses on the two most significant goals of simplicity and extensibility.

The TFA methodology (http://12factor.net) formulates key design principles to be used for building modern day SaaS apps. The web app could be written in any programming language and the same principles would be applied. Heroku enables the development of web apps based on this methodology by providing the necessary architectural foundation in the platform. In this section, we review these principles and relate their significance to...