A comprehensive guide to implementing the Saga Pattern in Node.js using NestJS and gRPC to handle distributed transactions across microservices. Covers orchestrated sagas (vs choreography), state machine design with explicit statuses (STARTED, AUTH_PROVISIONED, COMPENSATING, etc.), idempotency via a provision records table, compensation-based rollbacks in reverse dependency order, and observability using a shared sagaId as a distributed trace key. Includes a concrete agency onboarding example with two services (agency-service and auth-service), full code snippets, a testing matrix, trade-offs, and guidance on when not to use the pattern.
Table of contents
Table of ContentsPrerequisites1. Introduction2. The Problem in One Picture3. Why You Need a Saga4. Choreography vs Orchestration5. The Example Project6. Architecture7. The Saga Flow, Step by Step8. The State Machine9. Implementing the Orchestrator10. Implementing the Participant11. Rollback (Compensation)12. Tracking, Idempotency and Observability13. Testing a Saga14. When NOT to Use a Saga15. Trade-offs and Lessons Learned16. Conclusion1.3K Impressions