I use both AMQP and MQTT protocols in RabbitMQ. I use the pica library for AMQP and the paho library for MQTT. I can give a message limit when I define the tail with Pika (x-max-length). But when I use paho for MQTT, I cannot limit the message. If I give the queue 50 message limit in the AMQP, the number of messages in the queue will never exceed 50. Why can't I do this on MQTT, is there another way I can set a message limit?
https://www.youtube.com/watch?v=xcpxGJuOyBQ
There is a sample video. The broadcaster sends the message fast, but because the receiver is slow, too many messages accumulate in the broker. I always want to receive the last message.
Using rabbitmqctl you can directly set maximum length for queue using policies instead of doing that using client libraries.
Example:
rabbitmqctl set_policy my-pol "^one-meg$" '{"max-length-bytes":1048576}' --apply-to queues
Take a look on Queue Length Limit in official docs.
Related
I am sending messages to rabbitmq queue using mqtt protocol. I want to consume the messages using AMQP protocol. Instead of consuming the messages one by one. I want to consume the messages in batches and process them together. Is it possible with with RabbitMQ AMQP?
To read a group of messages in the queue together instead of reading one by one.
Instead of leaving Rabbit push messages to my consumers, the consumer connects to a queue and fetches a batch of N message.
Can't view rabbitmq queue messages after using the get messages command.
rabbitmqadmin get queue='queue_name' -H localhost -P 15672 -u rmq -p rmq --vhost=/ count=100
Queue count shows 100 messages, cant use the above command again to see the messages.
I would suggest to read https://www.rabbitmq.com/getstarted.html to understand how rabbitmq works.
The command get consumes the messages so you can't consume them anymore.
If you want to consume the same messages multi-times you can use the stream queue type.
When rabbitMq consumer consumes a mensagem from a queue the same will be deleted from the queue. If you just want to see the message you can log to the RabbitMQ Managment and read the messages, if they're not serialized. But if you want to consume the same message for some reason multiple times read the part of streams queue on the documentation.
I have to acknowledge all the unacknowledged message and make the count zero. If the message is in ready so the using the purge requester (DELETE http://localhost:8767/api/queues/vhost/name/contents) I am able to purge and remove the messages but if it is in unacked then this purge is not working or count still showing in the unacked section.
Kindly suggest how to use the REST API of RabbitMQ to ACK all the messages in the queue and make the count as zero.
you can ack them or purge queue in rabbitmq management
I want to obtain number of unacknowledged messages in RabbitMQ queue.
How can I achieve it?
I tried to use HTTP API, concretely /api/queues/vhost/name, but it always returns 0 messages_unacknowledged and messages
The HTTP (REST) API (management plugin) is not real time; it lags reality.
rabbitAdmin.getQueueProperties(queueName).get(org.springframework.amqp.rabbit.core.RabbitAdmin.QUEUE_MESSAGE_COUNT) does the job
RabbitAdmin is a bean which is automatically configured by Spring Boot.
I am using RabbitMQ with the MQTT plugin, with both producer and consumer on QoS=1.
I am still very new to RabbitMQ so I would like to understand if there is a way/efficient pattern to ensure a fallback in case a consumer is not consuming the messages of the topic he has subscribed to.
For instance, the idea being to be able to send an alert to a server trigger another channel (email, push notification) after a few seconds if a client is not consuming the messages of the MQTT topic?
Thank you for your help!
You can set per-message or per-queue TTL and then catch expired messages with the help of Dead Letter Exchanges extension. That will act as a notification of stalled or slow consumer or no consumers at all.