Building Idempotent Services: What Took Me So Long?

In early 2014, I began a focused push to make all critical services idempotent by design. Up until then, some retry mechanisms were "best effort."

But distributed systems don't forgive ambiguity. If you can't guarantee side-effect safety on retries, you don't have resilience.

What helped: - Using client-provided or auto-generated request IDs - Keeping state transitions explicit and tracked - Pairing with distributed tracing to validate call integrity

You don’t need idempotency everywhere—just everywhere that matters under failure.