saurabhprakash / rabbitmq-experiments Goto Github PK

Some useful commands:

• Running server(on local mac): sudo /usr/local/sbin/rabbitmq-server (On server run crash a probable error link: https://stackoverflow.com/questions/42895634/rabbitmq-server-boot-failed-on-mac-os-x-el-capitan/42898348#42898348)
• List queues: sudo rabbitmqctl list_queues
• Check queue contents: rabbitmqadmin get queue=<queue_name> requeue=true count=10
• Check unacknowledged messages(not acknowledged by consumer): rabbitmqctl list_queues name messages_ready messages_unacknowledged

Experiments:

• Tutorial 1 (https://www.rabbitmq.com/tutorials/tutorial-one-python.html): sender and reciver task, start a consumer(receive.py), which will run continuously waiting for deliveries. Start the producer(send.py). The producer program will stop after every run.
• Tutorial 2: working with workers, how to work with multiple workers, how rabbitmq handle situation when one worker dies(using help of acknowledgement), and how to handles cases when rabbitmq itself stops (https://www.rabbitmq.com/tutorials/tutorial-two-python.html): related files in current codebase - new_task.py, worker.py

Production checklist recommended by Rabbitmq: https://www.rabbitmq.com/production-checklist.html

Additional Important links:

• How the memory limit works: https://www.rabbitmq.com/memory.html
• How the disk limit works: https://www.rabbitmq.com/disk-alarms.html
• How clients can determine if they are blocked: https://www.rabbitmq.com/connection-blocked.html
• Networking guide: https://www.rabbitmq.com/networking.html

Create admin user on rabbitmq

• rabbitmqctl add_user
• rabbitmqctl set_user_tags administrator
• rabbitmqctl set_permissions -p / "." "." ".*"

Setup:

• installation :brew install rabbitmq
• start server: brew services start rabbitmq
• Server location: /usr/local/opt/rabbitmq/sbin/rabbitmq-server

For issue: "Error: Failure while executing; git config --local --replace-all homebrew.private true exited with 1." Refer this link: https://saurabhbuddha.blogspot.com/2018/10/rabbit-mq-issues-and-fixes-setup-issue.html

• It accepts, stores and forwards binary blobs of data ‒ messages.
• Producing means nothing more than sending. A program that sends messages is a producer
• A queue is the name for a post box which lives inside RabbitMQ. Although messages flow through RabbitMQ and your applications, they can only be stored inside a queue. A queue is only bound by the host's memory & disk limits, it's essentially a large message buffer. Many producers can send messages that go to one queue, and many consumers can try to receive data from one queue.
• Consuming has a similar meaning to receiving. A consumer is a program that mostly waits to receive messages
• Producer, consumer, and broker do not have to reside on the same host; indeed in most applications they don't. An application can be both a producer and consumer, too.
• RabbitMQ speaks AMQP 0.9.1, which is an open, general-purpose protocol for messaging. There are a number of clients for RabbitMQ in many different languages
• In RabbitMQ a message can never be sent directly to the queue, it always needs to go through an exchange.
• When a consumer (subscription) is registered, messages will be delivered (pushed) by RabbitMQ using the basic.deliver method. The method carries a delivery tag, which uniquely identifies the delivery on a channel. Delivery tags are therefore scoped per channel.
• Depending on the acknowledgement mode used, RabbitMQ can consider a message to be successfully delivered either immediately after it is sent out (written to a TCP socket) or when an explicit ("manual") client acknowledgement is received. Manually sent acknowledgements can be positive or negative and use one of the following protocol methods:

  basic.nack is used for negative acknowledgements (note: this is a RabbitMQ extension to AMQP 0-9-1)
  basic.reject is used for negative acknowledgements but has one limitation compared to basic.nack
  

• Installing pika: pip install pika
• Establish a connection with RabbitMQ server:

  #!/usr/bin/env python
  import pika
  
  connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
  channel = connection.channel()
  

• Create a queue to which the message will be delivered, Creating a queue using queue_declare is idempotent ‒ we can run the command as many times as we like, and only one will be created.

  channel.queue_declare(queue='<queue name>')
  

Tracelog setup imp links:

• http://www.mikeobrien.net/blog/tracing-rabbitmq-messages
• https://serverascode.com/2016/12/17/tracing-logging-rabbitmq.html
• https://www.rabbitmq.com/firehose.html