Software Fortresses: Modeling Enterprise Architectures

8.1. A Treaty between Two Fortresses

My morning usually starts at my local Starbucks. I am often there at 5:30 A.M. In fact, I am often there earlier, but until 5:30 A.M., I am forced to sit outside looking pitiful. When I get in, I need my doppio macchiato, I need it bad, and I need it made without mistakes.

Thinking of Starbucks in terms of fortresses, the counter forms a natural boundary between me and the Starbucks corporation. Starbucks is one self-contained fortress, and I am another. We interact across the counter. Each interaction goes through a drawbridge, and the sequence of interactions is defined by a treaty. I'll call this treaty the Purchase treaty.

Because both Starbucks and I are self-contained fortresses, we don't ask each other ...