python学习-day11

Posted 2020-08-15

一、Rabbitmq

       RabbitMQ 即一个消息队列，主要是用来实现应用程序的异步和解耦，同时也能起到消息缓冲，消息分发的作用。RabbitMQ使用的是AMQP协议，它是一种二进制协议。默认启动端口 5672。在 RabbitMQ 中，如下图结构：

• 左侧 P 代表 生产者，也就是往 RabbitMQ 发消息的程序。生产者需要完成的任务：

• 1 创建RabbitMQ连接
  2 获取信道
  3 声明交换器
  4 创建消息
  5 发布消息
  6 关闭信道
  7 关闭RabbitMQ连接 

• 中间即是 RabbitMQ，其中包括了 交换机 和 队列。
• 右侧 C 代表 消费者，也就是往 RabbitMQ 拿消息的程序。消费者需要完成的任务：

  1 创建RabbitMQ连接
  2 获取信道
  3 声明交换器
  4 声明队列
  5 队列和交换器绑定
  6 消费信息
  7 关闭信道
  8 关闭RabbitMQ连接

• Exchange: 接受客户端发送的消息，并根据Binding将消息路由给服务器中的队列，Exchange分为direct, fanout, topic三种。
• Binding: 连接Exchange和Queue，包含路由规则。
• Queue: 消息队列，存储还未被消费的消息。
• Message: Header+Body
• Channel: 通道，执行AMQP的命令；一个连接可创建多个通道以节省资源

1. dircted exchange

     路由键exchange，该交换机收到消息后会把消息发送到指定routing-key的queue中。rabbitmq内部默认有一个特殊的dircted exchange，该交换机的name是空字符串，所有queue都默认binding 到该交换机上。所有binding到该交换机上的queue，routing-key都和queue的name一样。

 生产者：

 1 import pika
 2 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 3 connection = pika.BlockingConnection(pika.ConnectionParameters(
 4     ‘192.168.170.134‘,5672,‘/‘,credentials))
 5 channel = connection.channel()
 6 
 7 # 声明queue
 8 channel.queue_declare(queue=‘hello‘)
 9 
10 # n RabbitMQ a message can never be sent directly to the queue, it always needs to go through an exchange.
11 channel.basic_publish(exchange=‘‘,
12                       routing_key=‘hello‘,
13                       body=‘Hello World!‘)
14 print(" [x] Sent ‘Hello World!‘")
15 connection.close()

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消费者：

 1 import pika
 2 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 3 connection = pika.BlockingConnection(pika.ConnectionParameters(
 4     ‘192.168.170.134‘,5672,‘/‘,credentials))
 5 channel = connection.channel()
 6 def callback(ch, method, properties, body):
 7     print(" [x] Received %r" % body)
 8 
 9 
10 channel.basic_consume(callback,
11                       queue=‘hello‘,
12                       no_ack=True)
13 
14 print(‘ [*] Waiting for messages. To exit press CTRL+C‘)
15 channel.start_consuming()

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 队列绑定关键字，发送者将数据关键字发送到消息Exchange，Exchange根据关键字判定应该将数据发送至指定队列。

生产者：

 1 import pika,sys
 2 
 3 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(
 5     ‘192.168.170.134‘,5672,‘/‘,credentials))
 6 channel = connection.channel()
 7 channel.exchange_declare(exchange=‘direct_logs‘,
 8                          type=‘direct‘)
 9 
10 severity = sys.argv[1] if len(sys.argv) > 1 else ‘info‘
11 message = ‘ ‘.join(sys.argv[2:]) or ‘Hello World!‘
12 channel.basic_publish(exchange=‘direct_logs‘,
13                       routing_key=severity,
14                       body=message)
15 print(" [x] Sent %r:%r" % (severity, message))
16 connection.close()

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消费者：

 1 import pika,sys
 2 
 3 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(
 5     ‘192.168.170.134‘,5672,‘/‘,credentials))
 6 channel = connection.channel()
 7 
 8 channel.exchange_declare(exchange=‘direct_logs‘,
 9                          type=‘direct‘)
10 
11 result = channel.queue_declare(exclusive=True)
12 queue_name = result.method.queue
13 
14 severities = sys.argv[1:]
15 if not severities:
16     sys.stderr.write("Usage: %s [info] [warning] [error]\\n" % sys.argv[0])
17     sys.exit(1)
18 
19 for severity in severities:
20     channel.queue_bind(exchange=‘direct_logs‘,
21                        queue=queue_name,
22                        routing_key=severity)
23 
24 print(‘ [*] Waiting for logs. To exit press CTRL+C‘)
25 
26 
27 def callback(ch, method, properties, body):
28     print(" [x] %r:%r" % (method.routing_key, body))
29 
30 
31 channel.basic_consume(callback,
32                       queue=queue_name,
33                       no_ack=True)
34 
35 channel.start_consuming()

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 运行结果：

2. fanout exchange

      发布/订阅exchange ，发布订阅和简单的消息队列区别在于，发布订阅会将消息发送给所有的订阅者，而消息队列中的数据被消费一次便消失。所以，RabbitMQ实现发布和订阅时，会为每一个订阅者创建一个队列，二发布者发布消息时，会将消息放置在所有相关队列中。任何发送到Fanout Exchange的消息都会被转发到与该Exchange绑定(Binding)的所有Queue上。

生产者：

 1 import pika,sys
 2 
 3 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(
 5     ‘192.168.170.134‘,5672,‘/‘,credentials))
 6 channel = connection.channel()
 7 # 声明queue
 8 channel.exchange_declare(exchange=‘logs‘,
 9                          type=‘fanout‘)
10 
11 message = ‘ ‘.join(sys.argv[1:]) or "info: Hello World!"
12 channel.basic_publish(exchange=‘logs‘,
13                       routing_key=‘‘,
14                       body=message)
15 print(" [x] Sent %r" % message)
16 connection.close()

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消费者：

 1 import pika
 2 
 3 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(
 5     ‘192.168.170.134‘,5672,‘/‘,credentials))
 6 channel = connection.channel()
 7 
 8 result = channel.queue_declare(exclusive=True)  # 不指定queue名字,rabbit会随机分配一个名字,exclusive=True会在使用此queue的消费者断开后,自动将queue删除
 9 queue_name = result.method.queue
10 
11 channel.queue_bind(exchange=‘logs‘,
12                    queue=queue_name)
13 
14 print(‘ [*] Waiting for logs. To exit press CTRL+C‘)
15 
16 
17 def callback(ch, method, properties, body):
18     print(" [x] %r" % body)
19 
20 
21 channel.basic_consume(callback,
22                       queue=queue_name,
23                       no_ack=True)
24 
25 channel.start_consuming()

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 3. topic exchange

      在topic类型下，可以让队列绑定几个模糊的关键字，之后发送者将数据发送到exchange，exchange将传入"路由值"和"关键字"进行匹配，匹配成功，则将数据发送到指定队列。

• # ：表示可以匹配0个或多个单词；

• * ：表示只能匹配一个单词。

生产者：

 1 import pika,sys
 2 
 3 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(
 5     ‘192.168.170.134‘,5672,‘/‘,credentials))
 6 channel = connection.channel()
 7 
 8 channel.exchange_declare(exchange=‘topic_logs‘,
 9                          type=‘topic‘)
10 
11 routing_key = sys.argv[1] if len(sys.argv) > 1 else ‘anonymous.info‘
12 message = ‘ ‘.join(sys.argv[2:]) or ‘Hello World!‘
13 channel.basic_publish(exchange=‘topic_logs‘,
14                       routing_key=routing_key,
15                       body=message)
16 print(" [x] Sent %r:%r" % (routing_key, message))
17 connection.close()

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消费者：

 1 import pika,sys
 2 
 3 credentials = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(
 5     ‘192.168.170.134‘,5672,‘/‘,credentials))
 6 channel = connection.channel()
 7 
 8 channel.exchange_declare(exchange=‘topic_logs‘,
 9                          type=‘topic‘)
10 
11 result = channel.queue_declare(exclusive=True)
12 queue_name = result.method.queue
13 
14 binding_keys = sys.argv[1:]
15 if not binding_keys:
16     sys.stderr.write("Usage: %s [binding_key]...\\n" % sys.argv[0])
17     sys.exit(1)
18 
19 for binding_key in binding_keys:
20     channel.queue_bind(exchange=‘topic_logs‘,
21                        queue=queue_name,
22                        routing_key=binding_key)
23 
24 print(‘ [*] Waiting for logs. To exit press CTRL+C‘)
25 
26 
27 def callback(ch, method, properties, body):
28     print(" [x] %r:%r" % (method.routing_key, body))
29 
30 
31 channel.basic_consume(callback,
32                       queue=queue_name,
33                       no_ack=True)
34 
35 channel.start_consuming()

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 二、基于rabbitmq的RPC

      基于rabbitmq的rpc实现流程：

    （1）首先客户端发送一个reply_to和corrention_id的请求,发布到RPC队列中；

    （2）服务器端处理这个请求，并把处理结果发布到一个回调Queue,此Queue的名称应当与reply_to的名称一致

    （3）客户端从回调Queue中得到先前correlation_id设定的值的处理结果。如果碰到和先前不一样的corrention_id的值，将会忽略而不是抛出异常。

  对于上面所提到的回调Queue中的消费处理使用的是BasicProperties类。

服务端：

 1 import pika
 2 
 3 cre_publiser = pika.PlainCredentials(‘admin‘, ‘123456‘)
 4 conn_para = pika.ConnectionParameters(‘192.168.170.134‘,5672,‘/‘,cre_publiser)
 5 connection = pika.BlockingConnection(conn_para)
 6 
 7 # 建立会话
 8 channel = connection.channel()
 9 
10 # 声明RPC请求队列
11 channel.queue_declare(queue=‘rpc_queue‘)
12 
13 # 数据处理方法
14 def fib(n):
15     if n == 0:
16         return 0
17     elif n == 1:
18         return 1
19     else:
20         return fib(n-1) + fib(n-2)
21 
22 # 对RPC请求队列中的请求进行处理
23 def on_request(ch, method, props, body):
24     n = int(body)
25 
26     print(" [.] fib(%s)" % n)
27 
28     # 调用数据处理方法
29     response = fib(n)
30 
31     # 将处理结果(响应)发送到回调队列
32     ch.basic_publish(exchange=‘‘,
33                      routing_key=props.reply_to,
34                      properties=pika.BasicProperties(correlation_id=props.correlation_id),
35                      body=str(response))
36     ch.basic_ack(delivery_tag = method.delivery_tag)
37 
38 # 负载均衡，同一时刻发送给该服务器的请求不超过一个
39 channel.basic_qos(prefetch_count=1)
40 
41 channel.basic_consume(on_request,
42                       queue=‘rpc_queue‘)
43 
44 print(" [x] Awaiting RPC requests")
45 channel.start_consuming()

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客户端：

 1 import pika
 2 import uuid
 3 class FibonacciRpcClient(object):
 4     def __init__(self):
 5         self.cre_publiser = pika.PlainCredentials(‘admin‘, ‘123456‘)
 6         self.conn_para = pika.ConnectionParameters(‘192.168.170.134‘,5672,‘/‘,self.cre_publiser)
 7         self.connection = pika.BlockingConnection(self.conn_para)
 8 
 9         self.channel = self.connection.channel()
10 
11         result = self.channel.queue_declare(exclusive=True)
12         self.callback_queue = result.method.queue
13 
14         self.channel.basic_consume(self.on_response,
15                                    no_ack=True,
16                                    queue=self.callback_queue)
17 
18     def on_response(self, ch, method, props, body):
19         if self.corr_id == props.correlation_id:
20             self.response = body
21 
22     def call(self, n):
23         self.response = None
24         self.corr_id = str(uuid.uuid4())
25         self.channel.basic_publish(exchange=‘‘,
26                                    routing_key=‘rpc_queue‘,
27                                    properties=pika.BasicProperties(
28                                    reply_to=self.callback_queue,
29                                    correlation_id=self.corr_id,
30                                    ),
31                                    body=str(n))
32         while self.response is None:
33             self.connection.process_data_events()
34         return int(self.response)
35 
36 
37 fibonacci_rpc = FibonacciRpcClient()
38 
39 print(" [x] Requesting fib(6)")
40 response = fibonacci_rpc.call(6)
41 print(" [.] Got %r" % response)

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