to orders
- order.created
- order.paid
- order.cancelled
sent 0 · confirmed 0 · returned 0 · nacked 0
RabbitMQ, live
One broker with a topic exchange, four queues and a few consumers, all running right here. Take a guided story, or play: add a publisher, crash a consumer, bind a queue with your own pattern, drag the timeline back, or type rabbitmqctl list_queues in the terminal.
Pick a story
Each story sets up a small broker and walks through it one event at a time. Guess what happens, then watch.
The basics
- One message, start to finish
Publisher, exchange, queue, consumer, ack: the whole path, slowly.
- Work queues: sharing the load
Two workers on one queue. Round-robin, a slow worker, and why prefetch 1 is fairer.
- A worker dies holding messages
Unacked messages come back, marked redelivered. With auto-ack they are lost.
Routing
- Fanout: one message, every queue
Publish/subscribe: a fanout exchange copies each message to all bound queues.
- Direct: route by exact key
Errors to one queue, everything to another; a key nobody bound is lost.
- Topic: route by pattern
Keys like quick.orange.rabbit and patterns like *.orange.* or lazy.#
- Messages that match nothing
Silently dropped, returned with mandatory, or caught by an alternate exchange.
When things go wrong
- Dead letters and poison messages
Rejected messages go to a dead-letter exchange; endless requeues are stopped by a delivery limit.
- TTL: messages that expire
A queue with a message TTL and a DLX makes a delay: the retry-later pattern.
- A full queue
x-max-length with drop-head pushes out the oldest; reject-publish refuses the newest.
What you see
- A message, in its routing key’s colour
- A delivery to a consumer
- An ack going back
- A nack, reject, drop or dead letter
- A binding, labelled with its key
- A consumer subscribed to a queue
- Where dead letters go
- A ready message in a queue (head on the right)
- An unacked message
- Redelivered
Publishers
Exchanges
in 0 · routed 0 · unroutable 0
3 bindings
in 0 · routed 0 · unroutable 0
1 bindings
Queues
- empty
in 0 · acked 0 · redelivered 0 · dead-lettered 0 · dropped 0
- empty
in 0 · acked 0 · redelivered 0 · dead-lettered 0 · dropped 0
- empty
in 0 · acked 0 · redelivered 0 · dead-lettered 0 · dropped 0
- empty
in 0 · acked 0 · redelivered 0 · dead-lettered 0 · dropped 0
Consumers
on billing
acked 0 · nacked 0 · rejected 0 · lost 0
on billing
acked 0 · nacked 0 · rejected 0 · lost 0
on shipping
acked 0 · nacked 0 · rejected 0 · lost 0
on audit
acked 0 · nacked 0 · rejected 0 · lost 0
Queue dead
Arguments
No arguments: a plain classic queue.
Bound from
- dlx
""
Consumers
Nobody is consuming from it.
Ready messages, head first
No ready messages.
NOTES
RabbitMQ notes
The concepts behind what you see above. They also live under Notes, tagged #rabbitmq.
- RabbitMQ: acks, prefetch and redeliveryWhy a queue keeps a message until the consumer acks it, how prefetch decides who gets the next one, and what happens to messages a consumer was holding when it dies.
- RabbitMQ: dead letters, TTL and length limitsWhere a queue sends the messages it gives up on, how message TTL and a dead-letter exchange make a delayed retry, and what a full queue does with one more message.
- RabbitMQ: exchanges, bindings and routingPublishers never write to queues. How the four exchange types decide which queues get a copy, what topic patterns match, and what happens to a message nothing matches.
- RabbitMQ vs KafkaA queue that forgets acked messages versus a log that keeps everything: how the two differ in routing, delivery, ordering, replay and failure, and when each fits.