Web applications are traditionally deployed to a certain software stack. Java enterprise applications for examples are deployed to an enterprise or Servlet container whereas server-side scripting languages such as PHP run on top of a web server. The applications therefore depend on their immediate runtime.

This 12-factor principle advise to develop self-sufficient applications that expose their functionality via network ports. Since web-based enterprise applications will communicate via the network, binding services to ports is the way of least coupling.

Java EE applications that run in a container support this approach, only exporting a port which is used to communicate with the application. Containers only depend on the Linux kernel, the application runtime is therefore transparent. Container orchestration frameworks leverage this idea, connecting services to pods via logical names and ports, as shown in a previous example. Java EE supports the use of containers and therefore this principle as well.