flowchart TB
  subgraph CL["Clients"]
    subgraph webapplayer["Web App"]
    end
  end
  subgraph APIL["API"]
    direction LR
    ex["Express App"]
    subgraph routers["Route Handlers"]
      routes["Routes"] --- endpoints["Endpoints"]
      click routes routesCallback "Routers use the express.Router class to create route handlers."
    end
    ex --- routers
  end
  subgraph SL["Service Layer"]
    direction TB
    s["Application Services"]
    s --- uow["Unit of Work"]
    uow --- rep["Repositories"]
  end
  subgraph DL["Data Access Layer"]
    pg["PostgreSQL"]
  end
  subgraph DO["Business Domain"]
    dm["Domain Models"]
    dto["Domain Transfer Objects"]
  end
  CL --- APIL
  APIL --- SL
  SL --- DL
  SL --- DO