Rabbit-Mq被拒绝后未路由到死信队列

Question

我目前正在玩Rabbit-Mq，并且正在尝试实现“死信”队列，即失​​败消息的队列。我一直在阅读Rabbit文档：https : //www.rabbitmq.com/dlx.html。

并提出了以下示例：

internal class Program
{
    private const string WorkerExchange = "work.exchange";
    private const string RetryExchange = "retry.exchange";
    public const string WorkerQueue = "work.queue";
    private const string RetryQueue = "retry.queue";

    static void Main(string[] args)
    {
        var factory = new ConnectionFactory { HostName = "localhost" };

        using (var connection = factory.CreateConnection())
        {
            using (var channel = connection.CreateModel())
            {
                channel.ExchangeDeclare(WorkerExchange, "direct");
                channel.QueueDeclare
                (
                    WorkerQueue, true, false, false,
                    new Dictionary<string, object>
                    {
                        {"x-dead-letter-exchange", RetryExchange},

                        // I have tried with and without this next key
                        {"x-dead-letter-routing-key", RetryQueue}
                    }
                );
                channel.QueueBind(WorkerQueue, WorkerExchange, string.Empty, null);

                channel.ExchangeDeclare(RetryExchange, "direct");
                channel.QueueDeclare
                (
                    RetryQueue, true, false, false,
                    new Dictionary<string, object> {
                        { "x-dead-letter-exchange", WorkerExchange },
                        { "x-message-ttl", 30000 },
                    }
                );
                channel.QueueBind(RetryQueue, RetryExchange, string.Empty, null);

                var consumer = new EventingBasicConsumer(channel);
                consumer.Received += (model, ea) =>
                {
                    var body = ea.Body;
                    var message = Encoding.UTF8.GetString(body);
                    Console.WriteLine(" [x] Received {0}", message);

                    Thread.Sleep(1000);
                    Console.WriteLine("Rejected message");

                    // also tried  channel.BasicNack(ea.DeliveryTag, false, false);
                    channel.BasicReject(ea.DeliveryTag, false);
                };

                channel.BasicConsume(WorkerQueue, false, consumer);

                Console.WriteLine(" Press [enter] to exit.");
                Console.ReadLine();
            }
        }
    }
}

发布到工作人员队列时的队列图像：

重试队列的图像：

我感觉好像丢失了一些小细节，但似乎找不到它们。

提前致谢

Answer 1

您应将Dead-letter-exchange定义为fanout。

我们去了： channel.ExchangeDeclare(RetryExchange, "fanout");

如果将死信交换设置为DIRECT，则必须指定死信路由密钥。如果您只是想让所有被NACKed的消息都进入一个死信箱中，以便以后进行调查（就像我一样），则应该将死信交换设置为FANOUT。

看看这个以获得更多信息

Answer 2

事实证明，如果死信交换是direct交换，那么队列参数需要一个x-dead-letter-routing-key. 上面（在问题中）我在字典中使用这个键来尝试路由我的消息，但我没有做的是向我的绑定添加路由，这里是代码的更新版本：

internal class Program
{
    private const string WorkerExchange = "work.exchange";
    private const string RetryExchange = "retry.exchange";
    public const string WorkerQueue = "work.queue";
    private const string RetryQueue = "retry.queue";

    static void Main(string[] args)
    {
        var factory = new ConnectionFactory { HostName = "localhost" };

        using (var connection = factory.CreateConnection())
        {
            using (var channel = connection.CreateModel())
            {
                channel.ExchangeDeclare(WorkerExchange, "direct");
                channel.QueueDeclare
                (
                    WorkerQueue, true, false, false,
                    new Dictionary<string, object>
                    {
                        {"x-dead-letter-exchange", RetryExchange},
                        {"x-dead-letter-routing-key", RetryQueue}
                    }
                );
                channel.QueueBind(WorkerQueue, WorkerExchange, WorkerQueue, null);

                channel.ExchangeDeclare(RetryExchange, "direct");
                channel.QueueDeclare
                (
                    RetryQueue, true, false, false,
                    new Dictionary<string, object>
                    {
                        {"x-dead-letter-exchange", WorkerExchange},
                        {"x-dead-letter-routing-key", WorkerQueue},
                        {"x-message-ttl", 30000},
                    }
                );
                channel.QueueBind(RetryQueue, RetryExchange, RetryQueue, null);

                var consumer = new EventingBasicConsumer(channel);
                consumer.Received += (model, ea) =>
                {
                    var body = ea.Body;
                    var message = Encoding.UTF8.GetString(body);
                    Console.WriteLine(" [x] Received {0}", message);

                    Thread.Sleep(1000);
                    Console.WriteLine("Rejected message");
                    channel.BasicNack(ea.DeliveryTag, false, false);
                };

                channel.BasicConsume(WorkerQueue, false, consumer);

                Console.WriteLine(" Press [enter] to exit.");
                Console.ReadLine();
            }
        }
    }

不同之处在于调用channel.QueueBind(WorkerQueue, WorkerExchange, WorkerQueue, null);now 提供的路由键与队列名称相同，因此当消息“死信”时，它会通过此键路由到交换