MQ死信和延时消息

MQ死信和延时消息

一、介绍：什么是死信队列？

1. 消息被拒(basic.reject or basic.nack)并且没有重新入队(requeue=false)；
2. 当前队列中的消息数量已经超过最大长度。
3. 消息在队列中过期，即当前消息在队列中的存活时间已经超过了预先设置的TTL(Time To Live)时间；

二、配置

1. 配置业务队列，绑定到业务交换机上
2. 为业务队列配置死信交换机和路由key
3. 为死信交换机配置死信队列

生产端：

public static void SendMessage()
        {
            var exchangeA = "exchange";
            var routeA = "routekey";
            var queueA = "queue";

            var exchangeD = "dlx.exchange";
            var routeD = "dlx.route";
            var queueD = "dlx.queue";

            using (var connection = RabbitMQHelper.GetConnection())
            {
                using(var channel = connection.CreateModel())
                {
                    // 创建死信交换机
                    channel.ExchangeDeclare(exchangeD, type: "fanout", durable: true, autoDelete: false);
                    // 创建死信队列
                    channel.QueueDeclare(queueD, durable: true, exclusive: false, autoDelete: false);
                    // 绑定死信交换机和队列
                    channel.QueueBind(queueD, exchangeD, routeD);

                    channel.ExchangeDeclare(exchangeA, type: "fanout", durable: true, autoDelete: false);
                    channel.QueueDeclare(queueA, durable: true, exclusive: false, autoDelete: false, arguments: 
                                        new Dictionary<string, object> {
                                             { "x-dead-letter-exchange",exchangeD}, //设置当前队列的DLX
                                             { "x-dead-letter-routing-key",routeD}, //设置DLX的路由key，DLX会根据该值去找到死信消息存放的队列
                                             { "x-message-ttl",10000} //设置消息的存活时间，即过期时间
                                         });
                    channel.QueueBind(queueA, exchangeA, routeA);


                    var properties = channel.CreateBasicProperties();
                    properties.Persistent = true;
                    //发布消息
                    channel.BasicPublish(exchange: exchangeA,
                                         routingKey: routeA,
                                         basicProperties: properties,
                                         body: Encoding.UTF8.GetBytes("hello rabbitmq message"));
                }
            }
            
        }

谢谢学习！！！