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Event-Driven Architecture

Event-Driven Architecture focuses on reacting to events and propagating facts across system boundaries.

This page shows how ForgingBlocks abstractions can participate in an event-driven design.

Important

ForgingBlocks does not require an event-driven architecture.
This page presents it as a pattern, not a mandate.

Quick summary

Event-Driven Architecture focuses on reacting to events and propagating facts across system boundaries. This page shows how ForgingBlocks abstractions can participate in this design — not required.

Mapping:
- Domain Events — Facts that occurred (Event, past tense, immutable)
- Event Handlers — React to events (EventHandler, MessageHandler[EventType, None])
- Message Bus — Routes events between components (MessageBusPort outbound port)
- Loose coupling — Components don't call each other directly

Fits when: loose coupling required; asynchronous processing desirable; frequent external system integration.

Conceptual mapping

  • Domain events represent facts that occurred.
  • Event handlers react to those events.
  • Message buses route events between components.
  • Components remain loosely coupled.

The diagram below shows a canonical event-driven flow from the literature.

---
title: Event-Driven Architecture
---
graph LR
    Producer[Producer<br/>Use Case] -->|publish| EventBusPort[Event Bus<br/>Message Bus]
    EventBusPort -->|dispatch| ConsumerA[Consumer A<br/>Event Handler]
    EventBusPort -->|dispatch| ConsumerB[Consumer B<br/>Event Handler]

When this style fits

  • Loose coupling is required.
  • Asynchronous processing is desirable.
  • Integration with external systems is frequent.