Read message with a consumer connected to an existing bus - .net-core

Question

I'm trying to understand how to connect consumers to an existing bus like explained here, but I don't understand how this thing should work
my code:
public interface IMessage
{
string Text { get; set; }
}
public class Program
{
public static void Main()
{
var bus = Bus.Factory.CreateUsingRabbitMq(sbc =>
{
var host = sbc.Host(new Uri("rabbitmq://localhost"), h =>
{
h.Username("guest");
h.Password("guest");
});
});
bus.Start();
bus.ConnectConsumer<TestConsumer>();
bus.Publish<IMessage>(new { Text = "Hi" });
Console.WriteLine("Press any key to exit");
Console.ReadKey();
bus.Stop();
}
}
public class TestConsumer : IConsumer<IMessage>
{
public Task Consume(ConsumeContext<IMessage> context)
{
Console.Out.WriteLineAsync($"Received: {context.Message.Text}");
return Task.CompletedTask;
}
}
I don't understand where the message is sent since aren't there any queue specified, and therefore I don't know how the message can be consumed.
Is there a way to specify on what queue the message will be sent and written OUTSIDE the bus definition?
What am I missing?

Answer 1

What you are publishing here
bus.Publish(new { Text = "Hi" });
is an anonymous type, not IMessage to which you are subscribed, i think you need to create IMessage interface, then create some class implementing IMessage and send over the bus

Answer 2

The docs you linked state that published messages are not received by the temporary queue and it has a limited set of use cases.
As far as I understand there's a distinction between senders and consumers in Mass Transit.
Senders send messages to an exchange not to queues.
Consumers are responsible for creating a queue and binding this queue to an exchange. The queue-exchange binding is done auto-magically based on the type of the message.
For this reason it's important that your consumers are created first. If the a message is sent without a consumer having created a queue the message has nowhere to go and will be lost.

Answer 3

Instead of using:
bus.ConnectConsumer<TestConsumer>();
Consider using:
sbc.ReceiveEndpoint("queue-name", e => e.Consumer<TestConsumer>());
That will create a queue named "queue-name" and connect your consumer to it.
If you need to connect a receive endpoint to the bus after the fact, you can use:
host.ConnectReceiveEndpoint("queue-name", e => e.Consumer<TestConsumer>());
You'll need to save the host from the configuration, but it will allow you to add the receive endpoint after the bus is started.