Rabbit-Mq被拒绝后不会路由到死信队列

Question

我正在玩Rabbit-Mq，我正在尝试实现一个“死信”队列，一个失败消息的队列。 我一直在阅读兔子文档： https ： //www.rabbitmq.com/dlx.html 。

并提出了这个例子：

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();
            }
        }
    }
}

发布到工作队列时的队列映像：

重试队列的图像：

我觉得好像我错过了一些小细节，但似乎无法找到它们是什么。

提前致谢

Answer 1

您应该将死信交换定义为fanout 。

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

如果您的死信交换设置为DIRECT，则必须指定死信路由密钥。 如果您只是希望所有NACKed消息进入死信桶以供以后调查（就像我一样）那么您的死信交换应设置为FANOUT。

请查看此信息以获取更多信息

Answer 2

事实证明，如果死信交换是direct交换，则队列参数需要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是我没做的是添加一个到我的绑定的路由，这里是一个有效的代码的更新版本：

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); 现在提供的路由密钥与queuename相同，所以当消息“dead-letters”时，它会通过这个密钥路由到交换机