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Infrastructure

Technical adapters

The Infrastructure block provides concrete implementations of outbound ports. It contains all technical details — I/O, serialization, networking, persistence.

Depends on Application (for port definitions), Domain (for aggregate types), and Foundation. Does not depend on Presentation.

How it works

Infrastructure adapters implement the contracts defined by Application outbound ports.

  • An InMemoryWriteRepository satisfies RepositoryPort with a dictionary.
  • An InMemoryEventBus satisfies EventBusPort with in-process publish/subscribe.
  • Each adapter encapsulates a technology choice behind a port interface.

The Application block only sees the port. You swap the adapter without touching application or domain code. A test injects an in-memory store. Production injects a PostgreSQL adapter. Same port, different implementation.

How to use

Start with in-memory implementations for fast feedback during development. They require no external services and run in tests. Graduate to real adapters when you need persistence, messaging, or external integration.

Adapters are composable:

  • A UnitOfWork wraps multiple repositories.
  • A MessageBus dispatches to multiple handlers.

Wire them together at startup — a composition root — and pass the resulting graph into the Application layer.

Core abstractions

What it does not do

  • Define business rules or domain logic
  • Orchestrate workflows
  • Make architectural decisions about port shape
  • Depend on Presentation

Glossary

Repository

Persists and retrieves domain aggregates. Implements RepositoryPort.

Unit of Work

Coordinates multiple repository operations within a transactional boundary.

Message Bus

Dispatches commands, queries, and events to registered handlers.

Event Store

Append-only event storage with optimistic concurrency for event sourcing.