Idempotency & Message Deduplication
Make retries safe with idempotency keys, dedupe stores, and exactly-once effects at the business layer.
Concept Breakdown
💡 Why It Matters
Payment double-charges, duplicate shipments, and poison retries are almost always missing idempotency boundaries.
🌐 Real-World Production Usages & Examples
Payment capture API
Scenario: Client retries POST /capture on timeout.
Outcome: Same idempotency key returns original receipt instead of double billing.
✓ When to Use
- •HTTP APIs with retries
- •Kafka consumers
- •Saga compensations
- •Webhook receivers
✕ When NOT to Use
- •Pure read-only queries with no side effects
- •Batch jobs that never retry
🔑 Core Architecture & Rules
- 1Idempotency keys stored with TTL
- 2Dedupe window must exceed max retry horizon
- 3Outbox pairs DB write with publish intent
⚖️ Architectural Trade-Off Analysis
Dedupe store
PROSimple correctness story
CONStorage and TTL governance required
⚠️ Failure Modes & Mitigations
Key collision
Different operations reuse the same idempotency key.
Mitigation: Scope keys per operation type and principal.
🛠️ Example Usages
Reviewed practical implementations and concrete code walkthroughs for Idempotency & Message Deduplication.
No reviewed practical examples currently published for this concept. Queued for technical review.
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Explore Related Concepts & Guides
Curated technical reading and direct concept relationships.
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Abstract AlgorithmsENGINEERING
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Message Queues
Consumers must tolerate redelivery.
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Transactional Outbox
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Transactional Outbox
Outbox publishing pairs with idempotent consumers.
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⚡ Next Step · Apply Concept
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