Subscribe without type?

jgauffin · February 10, 2021, 3:47pm

Is it possible to subscribe on events without having the correct type? (The assembly that the type is defined in is not loaded in the microservice that want to subscribe on the type).

Or do I manually have to bind the exchange ({namespace}:{typename}) to the correct queue using the rabbitmq client?

danielmarbach · February 12, 2021, 1:45pm

Hi Jonas

The transport uses the following convention

github.com

Particular/NServiceBus.RabbitMQ/blob/9c09fac7676c8bd10b709606cd8261f7f81f9a18/src/NServiceBus.Transport.RabbitMQ/Routing/ConventionalRoutingTopology.cs#L88


      
                  CreateExchange(channel, address);
                  channel.QueueBind(address, address, string.Empty);
              }
          }
          
          
public void BindToDelayInfrastructure(IModel channel, string address, string deliveryExchange, string routingKey)
          {
              channel.ExchangeBind(address, deliveryExchange, routingKey);
          }
          
          
static string ExchangeName(Type type) => type.Namespace + ":" + type.Name;
          
          
void SetupTypeSubscriptions(IModel channel, Type type)
          {
              if (type == typeof(object) || IsTypeTopologyKnownConfigured(type))
              {
                  return;
              }
          
          
    var typeToProcess = type;
              CreateExchange(channel, ExchangeName(typeToProcess));

This means you could redeclare the type locally in the same namespace. The problem is though that by default NServiceBus publishes the messages by setting the fully qualified assembly name. In order to be able to execute the handler, it would then be necessary to either publish without fully qualified assembly names like shown in the following sample

or in that endpoint of your Microservice replace the fully qualified assembly name in the incoming pipeline with the full name only.

Regards
Daniel