Glossary · Automation software engineering and architecture
Hexagonal architecture
Also known as: Ports and adapters architecture
German: Hexagonale Architektur
In software engineering, hexagonal architecture, also called ports and adapters, is an architecture pattern that places the application's core logic at the center, independent of external technologies, and connects it to user interfaces, databases, devices and other systems through defined ports implemented by exchangeable adapters.
- Software engineering
In one sentence
Hexagonal architecture keeps core logic independent of external technologies and connects it through ports and exchangeable adapters.
Example
The core of a machine data service defines a port 'ReadMachineState'; one adapter implements it via OPC UA, another via a simulator used in tests.
How it applies
- Engineering: The core contains the domain logic and does not depend on frameworks, protocols or databases. Adapters translate between ports and concrete technologies, such as OPC UA, MQTT, REST or a database, and can be replaced without touching the core.
- Testing: Because external dependencies sit behind ports, the core can be tested with simple test adapters, and technology changes, such as a new protocol, affect only one adapter.
- Documentation: Document the ports as the core's interfaces, and each adapter with the external system and version it connects to. This structure maps well onto integration documentation: one section per adapter.
Hexagonal vs. layered architecture
In Layered architecture, dependencies point downward through layers, and the domain logic often depends on the data access layer. In hexagonal architecture, all dependencies point inward toward the core; infrastructure depends on the core, not the other way around.