Technology: Event-Driven Architecture for Scalable Processes

Event-driven architecture (EDA) publishes important state changes as events, and other services react to those events. It works well for long, multi-stage, and cross-system workflows.

Why event-driven improves scalability

• Decoupling: producers do not need to know their consumers.
• Asynchronous work: heavy processing can run in the background without blocking users.
• Extensible: add new consumers by subscribing to events without changing producers.

Common EDA components

• Event broker or message queue for distribution.
• Stable, documented event schemas.
• Idempotent consumers with retry strategy.
• Dead-letter queues for failed events.

Design decisions to make early

• Idempotency: repeated events must not corrupt data.
• Ordering: decide if event order must be preserved.
• Delivery semantics: at-least-once vs exactly-once and the trade-offs.
• Observability: trace events end-to-end from publish to completion.

When EDA is not a fit

If a process is simple and synchronous flow is enough, EDA can add unnecessary complexity. Use EDA when decoupling and async execution are clearly needed.

Gradual adoption

1. Start with one important event (for example, RequestCreated).
2. Build a simple consumer (for example, send notifications).
3. Add monitoring and processing metrics.
4. Expand use cases gradually.

With a clean design, EDA makes systems more resilient to spikes, easier to grow, and easier to audit through event trails.