event-driven-architecture

Event-driven architecture enables decoupled microservices by using publish-subscribe messaging or event brokers. Services emit events when state changes occur, and other services consume those events independently, eliminating direct dependencies and allowing each service to scale and evolve separately.

Event sourcing stores the complete history of state changes as immutable events rather than current snapshots. This provides a full audit trail, enables temporal queries, supports event replay for debugging, and works naturally with eventual consistency patterns required in distributed systems.

Saga coordination patterns manage distributed transactions by breaking them into compensating steps. When a step fails, compensating actions reverse previous changes. Event-driven sagas use events to trigger and track these steps across services without requiring a central transaction manager.

Yes. Event-driven systems handle real-time data streams and high throughput through event brokers that decouple producers from consumers. Idempotent processing, versioned event schemas, and eventual consistency allow systems to scale horizontally while maintaining data integrity.

Eventual consistency improves availability and scalability but introduces temporary state divergence between services. Event-driven systems mitigate this through correlation IDs for tracing causation, immutable event logs, and careful event design to ensure all services eventually reach consistent state.

Reliable event processing requires idempotent handlers, an event store for persistence, correlation and causation tracing via IDs, and versioned schemas. These mechanisms prevent duplicate processing, enable recovery from failures, and maintain causal ordering critical for eventual consistency.