Background jobs, domain events, and side effects

When to use: Queues and workers, domain event publishers, async notifications or projections, or not doing that work inside HTTP handlers.

Side effects and eventing

• Domain code emits domain events through domain-level publisher abstractions (ports), not ad-hoc calls from use-cases to email/HTTP/Slack.
• Workers handle notifications, integrations, projections, and other I/O asynchronously.
• Do not orchestrate side effects (fan-out integrations, “fire and forget” HTTP, etc.) inside HTTP handlers — enqueue / publish and return.

Domain event naming and publisher–consumer decoupling

Domain events represent facts that happened — state transitions on an aggregate — not instructions for what should happen next. The publisher must never know or care which handlers are subscribed.

Rules