In message queueing a dead letter queue (DLQ) is a service implementation to store messages that the messaging system cannot or should not deliver. Although implementation-specific, messages can be routed to the DLQ for the following reasons:
- The message is sent to a queue that does not exist.
- The maximum queue length is exceeded.
- The message exceeds the size limit.
- The message expires because it reached the TTL (time to live)
- The message is rejected by another queue exchange.
- The message has been read and rejected too many times.
Routing these messages to a dead letter queue enables analysis of common fault patterns and potential software problems. If a message consumer receives a message that it considers invalid, it can instead forward it an Invalid Message Channel, allowing a separation between application-level faults and delivery failures.
Queueing systems that incorporate dead letter queues include Amazon EventBridge, Amazon Simple Queue Service, Apache ActiveMQ, Google Cloud Pub/Sub, HornetQ, Microsoft Message Queuing, Microsoft Azure Event Grid and Azure Service Bus, WebSphere MQ, Solace PubSub+, Rabbit MQ, Confluent Cloud and Apache Pulsar.
See also
References
- "Dead Letter Channel". www.enterpriseintegrationpatterns.com.
- ^ Redkar, Arohi (2004). Pro MSMQ: Microsoft Message Queue Programming. Apress. p. 148. ISBN 1430207329.
- "Dead-letter queues". IBM. Retrieved 23 February 2014.
- "Dead Letter Exchanges — RabbitMQ". www.rabbitmq.com. Retrieved 2020-12-06.
- ^ RabbitMQ dead letter queue "Dead Letter Exchanges". Archived from the original on 2016-05-05. Retrieved 2016-05-06.
- "Amazon SQS dead-letter queues". AWS. Archived from the original on 2023-04-14. Retrieved 2023-04-14.
- ^ "Using Amazon SQS Dead Letter Queues". Amazon. Retrieved 23 February 2014.
- "Invalid Message Channel". www.enterpriseintegrationpatterns.com. Archived from the original on 2023-04-14. Retrieved 2023-04-14.
- "Amazon EventBridge announces support for Dead Letter Queues". Amazon. Archived from the original on 2024-12-17. Retrieved 2020-10-30.
- "Forwarding to dead-letter topics | Cloud Pub/Sub". Google Cloud. Retrieved 2020-12-26.
- spelluru. "Compare Azure messaging services". docs.microsoft.com. Retrieved 2020-01-17.
- Böhm-Mäder, Johannes (14 December 2011). WebSphere MQ Security: Tales of Scowling Wolves Among Unglamorous Sheep. BoD. p. 68. ISBN 978-3842381506.
- "Solace Dead Message Queues".
- "Confluent Cloud documentation". Archived from the original on 2021-03-04. Retrieved 2021-02-12.
- "Apache Pulsar documentation".
- "Apache Pulsar PIP-22:Dead Letter Topic". GitHub.