队列名称可以不设置吗？

实践1

查看官网案例：emit_log.php
git地址：https://github.com/xiaochengfu/rabbitmq-tutorials/blob/master/php/emit_log.php

emit.log.php代码

<?php

require_once __DIR__ . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;
use PhpAmqpLib\Message\AMQPMessage;

$connection = new AMQPStreamConnection('59.110.213.203', 5672, 'guest', 'guest');
$channel = $connection->channel();

$channel->exchange_declare('logs', 'fanout', false, false, false);

$data = implode(' ', array_slice($argv, 1));
if (empty($data)) {
    $data = "info: Hello World!";
}
$msg = new AMQPMessage($data);

$channel->basic_publish($msg, 'logs');

echo ' [x] Sent ', $data, "\n";

$channel->close();
$connection->close();

现象

1. 声明了exchange,消息直接发送到了exchange中
2. 没有声明队列，也没有绑定队列

实践步骤

1. 执行php emit_log.php,通过管理后台查看logs交换机是否有和队列的绑定关系
2. 查看是否有队列接收到了发送的消息

结论

1. 生产者总是将消息发给exchange,甚至不用关心exchange有没有绑定的队列，消息到底发到了哪个队列

官网文档地址：https://www.rabbitmq.com/tutorials/tutorial-three-python.html
The core idea in the messaging model in RabbitMQ is that the producer never sends any messages directly to a queue. Actually, quite often the producer doesn't even know if a message will be delivered to any queue at all.

2，消息在没有到达队列内时，消息丢失了，说明exchange是不具有存储能力的

实践2

查看官网案例：receive_logs.php
git地址：https://github.com/xiaochengfu/rabbitmq-tutorials/blob/master/php/receive_logs.php

receive_logs.php代码

<?php

require_once __DIR__ . '/vendor/autoload.php';
use PhpAmqpLib\Connection\AMQPStreamConnection;

$connection = new AMQPStreamConnection('59.110.213.203', 5672, 'guest', 'guest');
$channel = $connection->channel();

$channel->exchange_declare('logs', 'fanout', false, false, false);

list($queue_name, ,) = $channel->queue_declare("", false, false, true, false);

$channel->queue_bind($queue_name, 'logs');

echo " [*] Waiting for logs. To exit press CTRL+C\n";

$callback = function ($msg) {
    echo ' [x] ', $msg->body, "\n";
};

$channel->basic_consume($queue_name, '', false, true, false, false, $callback);

while ($channel->is_consuming()) {
    $channel->wait();
}

$channel->close();
$connection->close();

现象

1. 声明队列时使用的空字符

实践步骤

1. 执行php receive_logs.php,通过管理后台查看exchange下是否有队列绑定
2. 查看队列是否能接收消息
3. 将队列的参数auto_delete改为true

结论

1. 声明队列的时候，使用空字符，可以生成一个名称为amqp.gen-xxx形式的临时队列
2. 对于临时队列的使用场景为：
   a. 消费者启动时创建的，为该消费者独有，其他交换机和消费者无法使用,所以参数exclusive设置为true
   b. 消费者关闭后，可以将auto_delete参数设置为true，自动将队列删除

答案

队列名称可以不设置，但生产者发出的消息，如果进不到队列里，消息将会丢失，队列名称可以设置空字符串，rabbitmq会生成一个临时的队列。