Is RabbitMQ at least once?

Is RabbitMQ at least once?

In RabbitMQ, exactly-once delivery is not supported due to the combination of complex routing and the push-based delivery. Generally, it’s recommended to use at-least-once delivery with idempotent consumers.

How does RabbitMQ guarantee delivery?

If a message is delivered to a consumer and then requeued, either automatically by RabbitMQ or by the same or different consumer, RabbitMQ will set the redelivered flag on it when it is delivered again. If the redelivered flag is not set then it is guaranteed that the message has not been seen before.

Does RabbitMQ guarantee order?

Message Ordering RabbitMQ provides few guarantees regarding the ordering of messages sent to a queue or exchange. Messages published in one channel, passing through one exchange and one queue and one outgoing channel will be received in the same order that they were sent.

What is at least once delivery?

means that for each message handed to the mechanism potentially multiple attempts are made at delivering it, such that at least one succeeds; again, in more casual terms this means that messages may be duplicated but not lost.

What is the difference between RabbitMQ and Kafka?

RabbitMQ is a general purpose message broker that supports protocols including, MQTT, AMQP, and STOMP. Kafka is a durable message broker that enables applications to process, persist and re-process streamed data. Kafka has a straightforward routing approach that uses a routing key to send messages to a topic.

What is the difference between Redis and RabbitMQ?

Redis is a database that can be used as a message-broker. On the other hand, RabbitMQ has been designed as a dedicated message-broker. RabbitMQ outperforms Redis as a message-broker in most scenarios. RabbitMQ guarantees message delivery.

What is the difference between RabbitMQ and ActiveMQ?

ActiveMQ is used in enterprise projects to store multiple instances and supports clustering environments based on the JMS messaging specification. RabbitMQ is a message broker which is executed in low-level AMQP protocol and acts as an intermediator between two application in the communication process.

How do you handle failed messages in RabbitMQ?

To handle the broker fails, you can store locally the failed messages then try to re-send them after x seconds.

Why can’t we have exactly once semantics?

People often bend the meaning of “delivery” in order to make their system fit the semantics of exactly-once, or in other cases, the term is overloaded to mean something entirely different. Consequently, guaranteeing at-least once semantics is sufficient and simplifies the implementation.

What is the reliability guide for RabbitMQ 0-9-1?

Reliability Guide. Overview. This guides provides an overview features of RabbitMQ, AMQP 0-9-1 and other supported protocols related to data safety. They help application developers and operators achieve reliable delivery, that is, to ensure that messages are always delivered, even encountering failures of various kinds.

What do acknowledgements and confirms mean on RabbitMQ?

Acknowledgements and confirms indicate that messages have been received and acted upon by the peer application. An acknowledgement signals both the receipt of a message, and a transfer of ownership where the receiver assumes full responsibility for it. Acknowledgements therefore have semantics.

What happens if RabbitMQ cannot handle a message?

If a consumer determines that it cannot handle a message then it can reject it using the basic.reject or basic.nack method, either asking the server to requeue it, or not (in which case the server might be configured to dead-letter it instead). When the queue a consumer was consuming from has been deleted, RabbitMQ will notify the consumer .

When does RabbitMQ set redelivered flag on a message?

If a message is delivered to a consumer and then requeued, either automatically by RabbitMQ or by the same or different consumer, RabbitMQ will set the redelivered flag on it when it is delivered again. This is a hint that a consumer may have seen this message before.