First experience of operating RabbitMQ in Python (1)

Because I wanted to use Python to implement a distributed system to manage and monitor the content and operating status of the CDN, I got to know RabbitMQ by accident. Many people recommended it, such as Yu Feng's "Why should I choose RabbitMQ" and so on .

When the word MQ came into view, I spent several hours reading about what MQ is, that is, Message Queue (Message Queue). As the name suggests, message queue, a queue filled with messages, queue, data structure noun, is a data structure with first-in first-out characteristics. The message queue is nothing more than used to deliver messages, so what is its significance, what are its application scenarios, what features it has, what are its unique advantages, and why it should be used. These are a series of questions that come to my mind.

After a long search, I finally came to a superficial understanding that message queue is a communication method for application-to-application information transmission. For example, if you need to analyze the logs of multiple servers, you can use one process on each server to write data, that is, the required information, into a Mysql database table, and then write several processes to read the data in the table and process the data. The analysis is not very good, but soon the ugliness of this design became apparent... Do you want multiple programs to fetch data from a queue for processing? No problem, we hardcoded the number of programs...what? Also allow the program to dynamically distribute pressure as it increases and decreases dynamically? This is an example from the very popular "RabbitMQ+Python Introduction to Classic Rabbit and Rabbit Nest". Think about it, when my CDN transmits a lot of data, data distribution, processing, everything will be a problem. But I still don’t understand how Rabbit implements these things.

Conceptually speaking, RabbitMQ is the standard implementation of AMPQ (Advanced Message Protocol Queuing). It is said that if you are not familiar with AMQP, you will not be able to understand the RabbitMQ documentation. But we can only build a large understanding of the key concepts. The entire RabbitMQ implementation principle model is shown in the figure below. It is actually a producer and consumer model with a routing task distribution queue. As shown in the figure, the producer produces corresponding information and sends it to the router. The router distributes the information to different message queues based on the key information in the information, and then the consumer reads the data in different message queues. the process of.

#Broker: Simply put, it is the message queue server entity.
Exchange: Message exchange, which specifies the rules according to which messages are routed to which queue.
Queue: Message queue carrier, each message will be put into one or more queues.
Binding: Binding, its function is to bind exchange and queue according to routing rules.
Routing Key: Routing keyword, exchange delivers messages based on this keyword.
Vhost: virtual host. Multiple vhosts can be opened in a broker to separate permissions for different users.
Producer: Message producer is the program that delivers messages.
Consumer: Message consumer is the program that accepts messages.
Channel: Message channel. In each connection of the client, multiple channels can be established, and each channel represents a session task.

The process of using message queue is roughly as follows:

(1) The client connects to the message queue server and opens a channel.
　(2) The client declares an exchange and sets related attributes.
　(3) The client declares a queue and sets related attributes.
　(4) The client uses routing key to establish a binding relationship between exchange and queue.
　(5) The client delivers the message to exchange.

After understanding the general process and advantages of RabbitMQ, I started to trial RabbitMQ on my own Fedora.

According to the RabbitMQ official website, the installation needs to be downloaded from here

rpm --import http://www.rabbitmq.com/rabbitmq-signing-key-public.asc yum install rabbitmq-server-3.3.0-1.noarch.rpm

chkconfig rabbitmq-server on

/sbin/service rabbitmq-server stop/start

grep beam.smp /var/log/audit/audit.log | audit2allow -M mypolsemodule -i mypol.pp/sbin/service rabbitmq-server start

pip install pika

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

channel.queue_declare(queue='sayhello')

channel.basic_publish(exchange='',                        
routing_key='hello',                                    
body='hello world')print "Sent ‘hello world'"

connection.close()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):    print " [x] Received %r" % (body,)

channel.basic_consume(callback,                      
queue='hello',                      
no_ack=True)print ' [*] Waiting for messages. To exit press CTRL+C'channel.start_consuming()