Understanding event delivery failures By David Boyne

Understanding event delivery failures By David Boyne

Understanding event delivery failures

When building event-driven applications it’s good to understand what happens if your event fails to reach consumers, what your broker may do for you or what you need to manage yourself.

Dead-letter queue

  • Place where events can go when failed to be delivered to consumer
  • Events can fail to be delivered, do you want to store them? (before they are dropped)
  • Use queue to debug errors or replay events back into system
  • For more information you can read Dead letter channel enterprise integration pattern.

Redrive policies

Archive/Replay

  • Store events that were raised and replay them into broker.
  • Worth making sure consumers are idempotent as messages may be replayed more than once
  • Outbox pattern can be used to store events before sending them.

Dropping events

  • Some event brokers may just drop the event if it cannot process it
  • Many brokers will retry given conditions, but worth checking and handling failures

Extra Resources

Want to work together?

If you're interested in collaborating, I offer consulting, training, and workshops. I can support you throughout your event-driven architecture journey, from design to implementation. Feel free to reach out to discuss how we can work together, or explore my services on EventCatalog.

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