Let's start by reviewing the basics of the software fortress model. This much of the model should be familiar to everybody in your organization, from the CTO to the end user:
The software fortress is a trust boundary. Everybody in the fortress trusts everybody else in the fortress, and nobody in the fortress trusts anybody outside the fortress.
The software fortress consists of many close-knit systems, machines, and processes. These systems, machines, and processes work together to solve a significant business problem, such as accounts payable.
Every fortress has one or more places where fortress-critical data is stored. These are collectively referred to as data strongboxes.
Every fortress is ...