先前例子中，我们创建了一个简单的日志系统，广播messages到consumer接收方。

但如果有日志错误级别的，不同的consumer接收不同错误级别的信息。比如consumer1接收info和warnging信息，consumer2接收error日志信息。这样的话，我们需要使用类型为direct的exchange type。

sender_direct.py

#!/usr/bin/env pythonimport pikaimport sysconnection = pika.BlockingConnection(pika.ConnectionParameters(        host='localhost'))channel = connection.channel()channel.exchange_declare(exchange='direct_logs',                         type='direct')severity = sys.argv[1] if len(sys.argv) > 2 else 'info'message = ' '.join(sys.argv[2:]) or 'Hello World!'channel.basic_publish(exchange='direct_logs',                      routing_key=severity,                      body=message)print(" [x] Sent %r:%r" % (severity, message))connection.close()

recv_direct.py

#!/usr/bin/env pythonimport pikaimport sysconnection = pika.BlockingConnection(pika.ConnectionParameters(        host='localhost'))channel = connection.channel()channel.exchange_declare(exchange='direct_logs',                         type='direct')result = channel.queue_declare(exclusive=True)queue_name = result.method.queueseverities = sys.argv[1:]if not severities:    sys.stderr.write("Usage: %s [info] [warning] [error]\n" % sys.argv[0])    sys.exit(1)for severity in severities:    channel.queue_bind(exchange='direct_logs',                       queue=queue_name,                       routing_key=severity)print(' [*] Waiting for logs. To exit press CTRL+C')def callback(ch, method, properties, body):    print(" [x] %r:%r" % (method.routing_key, body))channel.basic_consume(callback,                      queue=queue_name,                      no_ack=True)channel.start_consuming()