How do you make message consumers idempotent?
PICTURE THIS: HOW TO EXPLAIN IT
Simple meaning
I store processed message ids or use natural idempotency keys before side effects.
WHY — Messaging instead of guessing?
Why interviewers care about Messaging:
question about Messaging.
trade-offs, and what you would actually do on a .NET project - not buzzwords.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1I store processed message
ids or use natural idempotency keys before side effects.
- 2Why it exists
At-least-once brokers redeliver.
- 3How it works
Handlers must tolerate duplicates.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
I store processed message ids or use natural idempotency keys before side effects. At-least-once brokers redeliver.