ddd-event-driven

Event-driven architecture is a design paradigm where microservices communicate asynchronously through domain events, enabling decoupled systems. It uses event streams for state changes, allowing bounded contexts to operate independently while maintaining scalability.

To implement domain events in microservices, you model state changes as discrete events and publish them to an event stream. This allows bounded contexts to react to changes asynchronously, ensuring clear communication without tight coupling between services.

Use event sourcing in distributed systems when you need an immutable audit log or the ability to reconstruct past states. It uses append-only event streams as the primary source of truth, ensuring resilience and enabling complex temporal queries.

CQRS works effectively with event sourcing by separating command execution from query models. This pattern optimizes read and write operations independently, allowing distributed systems to scale efficiently by using tailored data stores for each operation.

Common event patterns for decoupled systems include Event Notification, Event-Carried State Transfer, and Event-Based Choreography. These patterns define how microservices exchange domain events to coordinate workflows without direct synchronous dependencies.

Use event-driven architecture over synchronous microservices to achieve higher scalability and resilience. By relying on asynchronous domain events, systems avoid blocking calls, reduce cascading failures, and allow bounded contexts to process state changes independently.