Backend Study Lab · Games

Backend concept

Asynchronous Reliability

Outbox relays, delivery guarantees, idempotent consumers, dead-letter recovery, and saga compensation.

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Key takeaway

Outbox relays, delivery guarantees, idempotent consumers, dead-letter recovery, and saga compensation. Start with the related games below when you want to turn the definition into practice.

Why this matters

Distributed workflows cross transaction boundaries, so correctness depends on explicit delivery and recovery behavior.

How to practice

Trace commit, publish, acknowledgement, retry, compensation, and replay boundaries before choosing a design.

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Local review for this concept

No local review items for this concept yet.

Start a focused review session for Asynchronous Reliability.

Learning objectives

  • Keep business state and publication intent atomic.
  • Handle relay concurrency and publish-confirm ambiguity.
  • Operate poison-event recovery safely.
  • Distinguish delivery from processing and side effects.
  • Place acknowledgments around durable work.
  • Name exactly-once boundaries precisely.

Common mistakes to avoid

  • Marking an event published before sending it.
  • Assuming a timeout proves broker failure.
  • Retrying poison events forever.
  • Acknowledging before durable work.
  • Treating timeouts as definite failure.
  • Promising exactly once without naming a boundary.

Games for Asynchronous Reliability

Start with the first game, then use local review history to revisit missed decisions.

Async Reliability Advanced

Outbox Relay Recovery

Recover a transactional outbox relay across commit, publish-confirm, duplicate delivery, and poison-event failure windows.

Time
8-12 minutes
Concept
Transactional outbox and relay recovery
  • Async Workflows
  • outbox
  • transactions
  • messaging
Play Outbox Relay Recovery
Async Reliability Advanced

Delivery Guarantee Timeline

Trace producer, broker, consumer, acknowledgment, crash, and redelivery boundaries to name the real delivery guarantee.

Time
7-10 minutes
Concept
Message delivery semantics and acknowledgment timing
  • Async Workflows
  • delivery semantics
  • acknowledgments
  • retries
Play Delivery Guarantee Timeline
Async Reliability Advanced

Idempotent Consumer Lab

Build duplicate-safe consumers with scoped event identity, database constraints, and atomic business mutations.

Time
8-11 minutes
Concept
Idempotent message consumers
  • Async Workflows
  • idempotency
  • consumers
  • constraints
Play Idempotent Consumer Lab
Async Reliability Advanced

DLQ Recovery Console

Classify failures, bound retries, quarantine poison messages, and replay dead-letter work with approval and idempotency.

Time
8-12 minutes
Concept
Dead-letter queue operations
  • Async Workflows
  • dlq
  • retries
  • operations
Play DLQ Recovery Console