RTS Questionnaire · Question 46 of 52 · file: answers/q46.html
Have you worked with distributed-system patterns such as CQRS, Event Sourcing, Transactional Outbox, Saga, Event-driven architecture, Idempotency, or Retry/Circuit Breaker? If yes, which patterns have you implemented and for how long?
PatternsDistributedArchitecture
✅ Yes — I have implemented most of these patterns in production, over roughly 6+ years of distributed-systems work.
🧪 Interactive proof: this answer has its own page with a live pattern inventory, the durations and trade-offs per pattern, the event-sourced aggregate and the failure-path tests behind it — open the Q46 distributed-patterns proof →
Technical detail
- 📚 CQRS — separated write model from read models/projections, optimised query paths (denormalised views, materialised reads) and kept the command side transactional and validated.
- 🗃️ Event Sourcing — append-only event logs as the source of truth with projections rebuilt on demand; useful for audit-heavy domains (financial movements, approvals, workflow history) where the full history matters.
- 📤 Transactional Outbox — atomic "state + event" writes with a relay/publisher, guaranteeing reliable publication to Kafka/RabbitMQ/Service Bus without 2PC; combined with inbox/dedup tables on the consumer side.
- 🔄 Saga — choreographed and orchestrated long-running transactions with compensating actions for order/payment/provisioning-style flows, plus timeouts and manual-intervention escape hatches.
- ⚡ Event-driven architecture — topics/queues with clear schemas, versioning and ownership; producers/consumers decoupled, replayable and observable.
- 🔁 Idempotency — idempotency keys, deduplication stores, conditional writes and unique constraints so at-least-once delivery produces exactly-once business effects.
- 🛡️ Retry / Circuit Breaker — Polly-style policies with exponential backoff and jitter, circuit breakers, bulkheads, timeouts and fallbacks so a failing dependency degrades gracefully instead of cascading.
🧠 I also apply the discipline around them: pattern choice justified in an ADR, failure paths tested (chaos-style and integration tests), and metrics/alerting that reveal backlog, retries and compensation events before customers notice.
🧾 CV evidence: CV: AWS event-driven architectural microservices, CQRS-ready hexagonal microservice assessment (2025), MQ systems (Kafka/RabbitMQ/ActiveMQ), resilience and idempotency patterns documented in technical assessments; AWS Step Functions orchestration.