RabbitMQ is an open source & enterprise level messsage broker using
AMQP protocal. The
AMQP protocol is designed for asychronization and message dispatch. RabbitMQ can be used in time-consuming backend jobs such as sending emails to client, generating file for user to download, and so on.
Install on Mac
brew update brew install rabbitmq
Then install the client
Pika for RabbitMQ
pip install pika
Consumer & Producer Problem:
In parallel programming,
Consumer & Producer Problem refers to one type of the most frequently used cases. Simply, Producers create data in a fixed size cache, while Consumers would take data from that cache. To make the whole process working properly, it is a must that producers would not produce new data while the cache is full, and consumers will not take more when the cache is empty.
VHOST (Virtual host) in RabbitMQ
Vhost is an important concept in RabbitMQ, which you can create queue, binding and exchange seperately. By default, RabbitMQ comes with a inner-built vhost named ‘/’. However we need more vhosts, queues to organize our tasks when there are too many. Just like in programing we have different naming space and modules.
? Step 1:
Create a new user with name ben and password 1234
sudo /usr/local/sbin/rabbitmqctl add_user ben 1234
? Step 2:
Create a new vhost
sudo /usr/local/sbin/rabbitmqctl add_vhost new_host
? Step 3:
Set permissions on the new vhost
sudo /usr/local/sbin/rabbitmqctl set_permissions -p new_host ben ".*" ".*" ".*"
1st “.*” means enable user
ben to add and delete
2nd “.*” means enable user
ben to publish new messages
3rd “.*” means enable user
ben to read new messages
? Step 4:
Now we can gete all the vhosts in current system
➜ ~ /usr/local/sbin/rabbitmqctl list_vhosts Listing vhosts / new_host ➜ ~
? Step 5:
Sure thing we can list all the queues in a vhost:
/usr/local/sbin/rabbitmqctl list_queues -p /
➜ ~ /usr/local/sbin/rabbitmqctl list_queues -p / Listing queues standard 0
? Step 6:
There is also an additional cmd to get all the users:
➜ ~ /usr/local/sbin/rabbitmqctl list_users Listing users ben  guest [administrator] ➜ ~
Show me the code!
The following is an full working example:
import sys import pika parameters = pika.URLParameters('amqp://guest:guest@localhost:5672/%2F') connection = pika.BlockingConnection(parameters) channel = connection.channel() channel.exchange_declare(exchange='web_develop', exchange_type='direct', passive=False, durable=True, auto_delete=False) if len(sys.argv) != 1: msg = sys.argv else: msg = 'hah' props = pika.BasicProperties(content_type='text/plain', delivery_mode=2) channel.basic_publish('web_develop', 'xxx_routing_key', msg, properties=props) connection.close()
import pika def on_message(channel, method_frame, header_frame, body): channel.basic_ack(delivery_tag=method_frame.delivery_tag) print body parameters = pika.URLParameters('amqp://guest:guest@localhost:5672/%2F') connection = pika.BlockingConnection(parameters) channel = connection.channel() channel.exchange_declare(exchange='web_develop', exchange_type='direct', passive=False, durable=True, auto_delete=False) channel.queue_declare(queue='standard', auto_delete=True) channel.queue_bind(queue='standard', exchange='web_develop', routing_key='xxx_routing_key') channel.basic_consume(on_message, 'standard') try: channel.start_consuming() except KeyboardInterrupt: channel.stop_consuming() connection.close()
Run with consumer first,
python rabbitmq_producer.py msg in another terminal. You would find out a new message showing up from consumer terminal.
By default, RabbitMQ provides a default account with
Guest with admin privilege. When publishing to production, password must be changed!