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：

重试队列的图片：

我觉得我好像错过了一些小细节，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，您必须指定一个   死信路由键。如果您只想要所有NACKed消息   进入一个死信桶，以便以后调查（就像我一样）   你的死信交换应该设置为FANOUT。

Look at this for more info

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，但我没有做的是添加一个路由到我的绑定，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();
            }
        }
    }

不同之处在于对channel.QueueBind(WorkerQueue, WorkerExchange, WorkerQueue, null);的调用现在提供的路由键与queuename相同，所以当消息＆＃34; dead-letters＆＃34;它通过此密钥路由到交易所

Answer 3

要使其正常工作，最主要的是用确切的路由键将WorkerExchange和WorkerQueue绑定。应该通过RabbitMq UI Manager为work.exchange配置它。

然后使用此路由密钥通过WorkerExchange将消息添加到WorkerQueue。 然后，这些“死队列”消息将存储在retry.queue

中。

channel.QueueDeclare
            (
                WorkerQueue, true, false, false,
                new Dictionary<string, object>
                {
                    {"x-dead-letter-exchange", RetryExchange}
                }
            );

这是C＃代码中队列声明所需要的。

不需要额外的参数{"x-dead-letter-routing-key", RetryQueue}。

也不需要以下代码行：

channel.ExchangeDeclare(WorkerExchange, "direct");

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);

因此您可以删除上述行。

Rabbit-Mq被拒绝后不会路由到死信队列

3 个答案: