The seventh factor is related to port binding, which is how the application is reachable, and exposed. A cloud-native application doesn't need any runtime, such as application servers or web servers; everything is embedded, and it's self-contained and exposes its services (such as APIs) through ports via the protocol that best fits its integration functionalities (HTTP, AMQP, MQTT, XMPP, and so on).

That also means, that if you expose your application, it can be a backing service for another application. The cloud infrastructure will provide routing capabilities.