Question

我在 RabbitMQ 中有一个队列。我无法配置这个队列，我必须使用它的消息。发布者不使用大众运输进行发布。我正在使用 Masstransit 来使用队列中的消息。

当我尝试配置与队列的连接时，收到此错误：

The AMQP operation was interrupted: AMQP close-reason, initiated by Peer, code=406, text='PRECONDITION_FAILED - inequivalent arg 'type' for exchange 'my_queue' in vhost 'my_vhost': received 'fanout' but current is 'direct'', classId=40, methodId=10

我的配置如下：

Bus.Factory.CreateUsingRabbitMq(cfg =>
{
    cfg.Host("127.0.0.1", "my_virtual_host", credintials =>
    {
        credintials.Username("myuser");
        credintials.Password("mypassword");
    });

    cfg.ReceiveEndpoint("my_queue", e =>
    {

        e.UseRawJsonSerializer();
        e.Consumer(() => _messageConsumer);
    });
}).Start();

队列有配置 Durable = true 就是这样，没什么特别的。

当我尝试通过 RabbitMQ.Client 连接到队列时，它连接没有问题。消费也很有效。

我该如何解决问题？

Answer 1

问题是 my_queue 交换已经存在，具有直接交换类型。默认情况下，MassTransit 将此交换创建为扇出交换。直接交换用于通过路由键路由消息。有关使用 MassTransit 直接交换的示例，请查看 direct 示例。

您可以看到 MassTransit 为 RabbitMQ 配置的 broker topology。

Answer 2

我解决了我的问题。与 Masstransit 的连接如下所示：

private async Task InitMasstransitBusAsync(CancellationToken cancellationToken)
{
    await Bus.Factory.CreateUsingRabbitMq(cfg =>
    {
        cfg.Host(new Uri(_rabbitMqConfig.HostName), credintials =>
        {
            credintials.Username(_rabbitMqConfig.UserName);
            credintials.Password(_rabbitMqConfig.Password);

        });
        cfg.ReceiveEndpoint(_rabbitMqConfig.QueueName, e =>
        {
            e.PrefetchCount = 20;
            e.ExchangeType = "direct";
            e.ConfigureConsumeTopology = false;
            e.AddMessageDeserializer(new ContentType("text/plain"),
                () => new CustomMessageDeserializer("text/plain"));
            e.Consumer(() => _messageConsumer);
        });
    }).StartAsync(cancellationToken);
}

CustomMessageDeserializer：

    public class CustomMessageDeserializer : IMessageDeserializer
    {
        private readonly string _contentType;
        private readonly JsonSerializer _serializer = JsonSerializer.Create();

        public CustomMessageDeserializer(string contentType)
        {
            _contentType = contentType;
        }

        public ContentType ContentType => new(_contentType);

        public ConsumeContext Deserialize(ReceiveContext receiveContext)
        {
            try
            {
                var messageEncoding = GetMessageEncoding(receiveContext);
                using var body = receiveContext.GetBodyStream();
                using var reader = new StreamReader(body, messageEncoding, false, 1024, true);
                using var jsonReader = new JsonTextReader(reader);
                var messageToken = _serializer.Deserialize<JToken>(jsonReader);
                
                return new RawJsonConsumeContext(_serializer, receiveContext, messageToken);
            }
            catch (JsonSerializationException ex)
            {
                throw new SerializationException("A JSON serialization exception occurred while deserializing the message", ex);
            }
            catch (SerializationException)
            {
                throw;
            }
            catch (Exception ex)
            {
                throw new SerializationException("An exception occurred while deserializing the message", ex);
            }
        }

        public void Probe(ProbeContext context) { }

        public static Encoding GetMessageEncoding(ReceiveContext receiveContext)
        {
            var contentEncoding = receiveContext.TransportHeaders.Get("Content-Encoding", default(string));
            return string.IsNullOrWhiteSpace(contentEncoding) ? Encoding.UTF8 : Encoding.GetEncoding(contentEncoding);
        }

    }

Masstransit 无法从 c# 应用程序连接到 RabbitMQ 中的队列

2 个答案: