Ports

The domain speaks through ports, never directly to infrastructure.

Ports are interfaces — they declare what the domain needs without specifying how. Driving ports accept commands from the outside. Driven ports request services from the outside. The domain owns both.

Context

• Adapters — Concrete implementations plugged into ports
• Hexagonal Architecture — The pattern that separates domain from infrastructure

Questions

How do you know when a port interface is at the right level of abstraction?

• What breaks when a port leaks infrastructure concerns into the domain?
• When should a single port split into multiple narrower interfaces?