Transaction Script

Transaction Script organizes business logic as procedures, each handling one request or business transaction. It is a good default for simple domains where a rich object model would add ceremony without reducing complexity.

src/app/
├── interface/
├── transactions/
└── data_access/

Complete Configuration

deply:
  paths: ["."]
  exclude_files:
    - '.*/\.venv/.*'
    - '.*/tests?/.*'
  layers:
    - name: interface
      collectors:
        - type: directory
          directories: ["src/app/interface"]
    - name: transactions
      collectors:
        - type: directory
          directories: ["src/app/transactions"]
    - name: data_access
      collectors:
        - type: directory
          directories: ["src/app/data_access"]
  ruleset:
    interface:
      disallow_layer_dependencies: [data_access]
    transactions:
      disallow_layer_dependencies: [interface]
    data_access:
      disallow_layer_dependencies: [interface, transactions]

Transaction scripts may call data access directly. Move behavior into a domain model or service layer only when duplication and business invariants make the procedural model difficult to maintain.

Deply can enforce the package direction, but it cannot determine whether a transaction script has become too complex or whether its transaction is atomic.

Validate

deply validate --config=deply.yaml
deply analyze --parallel --config=deply.yaml

Reference: Fowler’s Transaction Script.