Clean Architecture: A Craftsman's Guide to Software Structure and Design

25LAYERS AND BOUNDARIES

It is easy to think of systems as being composed of three components: UI, business rules, and database. For some simple systems, this is sufficient. For most systems, though, the number of components is larger than that.

Consider, for example, a simple computer game. It is easy to imagine the three components. The UI handles all messages from the player to the game rules. The game rules store the state of the game in some kind of persistent data structure. But is that all there is?

HUNT THE WUMPUS

Let’s put some flesh on these bones. Let’s assume that the game is the venerable Hunt the Wumpus adventure game from 1972. This ...