RabbitMQ Sample

RabbitMQ：

Before using RabbitMQ, we must first understand its working mechanism

By vhost separated by the multi-tenant, no interference between the different services of the same rabbitMQ vhost

Create exchange, to determine its category. Then create a queue, and bind with the exchange, like all subscribe to the same as the exchange of messages. But not all arrive at the exchange of messages will be distributed to the queue, but distinguished by routing key. A queue can be bound to multiple exchange.

Information in a queue to be consumed only once, if multiple consumer will want to get the message, each consumer should each have opened a queue, to subscribe message, and then to spend their own queue.

import pika

username = "my_username"
password = "special_pw"
host = "192.168.0.1"
port = "5672"
vhost = "my_vhost"

credentials = pika.PlainCredentials(username, password)
conn_params = pika.ConnectionParameters(host, port, vhost, credentials)
conn = pika.BlockingConnection(conn_params)


def create():
    # 任何操作都是在channel中进行，所以需要先创建一个channel
    channel = conn.channel()

    # 创建一个exchange
    # durable: rabbitmq服务重启之后该exchange是否还存在
    # auto_delete: 当没有queue绑定该exchange的时候，自动删除该exchange
    channel.exchange_declare("exchange_name", exchange_type="topic", durable=True, auto_delete=False)

    # 创建一个队列
    # passive: 被动，只检查是否已经存在，如果不存在该queue，报错
    # durable: rabbitmq服务重启之后是否还在
    # exclusive: 创建的队列只能为当前的channel使用
    # auto_delete: 没有consumer的时候，自动删除
    channel.queue_declare("queue_name", passive=False, durable=False, exclusive=False, auto_delete=False)

    # 将指定的队列绑定到指定的exchange，并定义routing_key
    channel.queue_bind("queue_name", "exchange_name", routing_key="#.chat_end")

    # 向指定的exchange推送消息
    channel.basic_publish("exchange_name", routing_key="#.chat_end", body="string_type_can_be_json")

    # 消费指定的queue
    def callback_fn(channel, method, properties, body):
        # 收到的消息都是binary，需要先decode
        msg = body.decode()

    # 消费指定队列的queue，第二个参数为回调函数
    channel.basic_consume("queue_name", callback_fn, auto_ack=True)

    # 删除不用的queue或者exchange
    channel.queue_delete("queue_name")
    channel.exchange_delete("exchange_name")

    # 开启消费队列
    channel.start_consuming()

    channel.close()