Question

“持久”和“持久模式”似乎与重新启动有关，而不是与没有订阅者接收消息有关。

我希望RabbitMQ在没有订阅者时将消息保留在队列中。当订户上线时，该订户应该接收该消息。 RabbitMQ可以实现吗？

代码示例：

服务器

namespace RabbitEg
{
    class Program
    {
        private const string EXCHANGE_NAME = "helloworld";

        static void Main(string[] args)
        {
            ConnectionFactory cnFactory = new RabbitMQ.Client.ConnectionFactory() { HostName = "localhost" };

            using (IConnection cn = cnFactory.CreateConnection())
            {
                using (IModel channel = cn.CreateModel())
                {
                    //channel.ExchangeDelete(EXCHANGE_NAME);
                    channel.ExchangeDeclare(EXCHANGE_NAME, "direct", true);
                    //channel.BasicReturn += new BasicReturnEventHandler(channel_BasicReturn);

                    for (int i = 0; i < 100; i++)
                    {
                        byte[] payLoad = Encoding.ASCII.GetBytes("hello world _ " + i);
                        IBasicProperties channelProps = channel.CreateBasicProperties();
                        channelProps.SetPersistent(true);

                        channel.BasicPublish(EXCHANGE_NAME, "routekey_helloworld", false, false, channelProps, payLoad);

                        Console.WriteLine("Sent Message " + i);
                        System.Threading.Thread.Sleep(25);
                    }

                    Console.ReadLine();
                }
            }
        }
    }
}

客户端：

namespace RabbitListener
{
    class Program
    {
        private const string EXCHANGE_NAME = "helloworld";

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

            using (IConnection cn = cnFactory.CreateConnection())
            {
                using (IModel channel = cn.CreateModel())
                {
                    channel.ExchangeDeclare(EXCHANGE_NAME, "direct", true);

                    string queueName = channel.QueueDeclare("myQueue", true, false, false, null);
                    channel.QueueBind(queueName, EXCHANGE_NAME, "routekey_helloworld");

                    Console.WriteLine("Waiting for messages");

                    QueueingBasicConsumer consumer = new QueueingBasicConsumer(channel);
                    channel.BasicConsume(queueName, true, consumer);

                    while (true)
                    {
                        BasicDeliverEventArgs e = (BasicDeliverEventArgs)consumer.Queue.Dequeue();
                        Console.WriteLine(Encoding.ASCII.GetString(e.Body));
                    }
                }
            }
        }
    }
}

Answer 1

有关durable和persistent的含义的解释，请参阅AMQP Reference。

基本上，队列是durable或non-durable。前者在经纪人重启后继续存在，后者则没有。

邮件发布为transient或persistent。我们的想法是persistent队列上的durable消息也应该在代理重启后继续存在。

因此，要获得所需内容，您需要1）将队列声明为durable，2）将消息发布为persistent。此外，您可能还想在频道上启用发布商确认;这样，你就会知道经纪人何时承担了这条消息的责任。

没有订阅者的RabbitMQ队列

1 个答案: