Understanding the self-containment design pattern

Systems that employ the self-containment reactive design pattern are not reliant on non-system components. This design pattern can also be applied at the system component level. In that instance, a system component would be self-contained and not rely on other system components.

To examine the self-containment reactive design pattern, let's first consider a system diagram depicting a lack of self-containment. As you can see from the next diagram, the Financial Services API is the only system component with access to the Payment Gateway and the related database. Both the New Vehicle Sales and service department sales shown by Service Dept Sales nodes, rely on the Financial Services API for access to its sub-components:

System in need of the self-containment design pattern

This architecture is not advised, as the reliance that...