Event-Driven Architecture

Event-driven architecture (EDA) is a design pattern where system components communicate by producing and consuming events — records of something that happened (e.g., "order placed," "payment received," "user registered").

Key components include event producers (services that emit events), event consumers (services that react to events), event brokers (middleware like Apache Kafka, RabbitMQ, or AWS EventBridge that routes events), and event stores (persistent logs of all events).

EDA enables loose coupling (producers don't know about consumers), scalability (consumers can be scaled independently), resilience (if a consumer is down, events are buffered), and real-time processing (react to changes immediately).

Patterns within EDA include event sourcing (storing state as a sequence of events), CQRS (separating read and write models), choreography (services react to events independently), and orchestration (a coordinator directs the flow). EDA is common in e-commerce, financial systems, IoT, and real-time analytics.