MassTransit - A convention for the message type {typename} was not found

While preparing a presentation I created a simple demo app where I wanted to publish a message to a queue.

My first (naïve) attempt looked like this:

This failed with the following error message:

A convention for the message type {typename} was not found

	var bus = Bus.Factory.CreateUsingRabbitMq(sbc =>
	{
	var host = sbc.Host(new Uri("rabbitmq://localhost:32778"), h =>
	{
	h.Username("guest");
	h.Password("guest");
	});
	});
	bus.Send(new ProcessSampleCommand() { Id = Guid.NewGuid() });

view raw MassTransitFirstAttempt.cs hosted with ❤ by GitHub

What was my mistake?

In MassTransit you have to make a difference between sending a message and publishing a message. Whereas publishing a message doesn’t require any extra configuration, sending a message does. Why? Because when sending a message you directly target a queue. MassTransit has to know which queue the message should be send to.

We have 2 options to make this work:

1) You specify the target queue using a convention:

EndpointConvention.Map<ProcessSampleCommand>(new Uri("rabbitmq://localhost:32778/sample_queue"));

view raw MassTransitEndpointConvention.cs hosted with ❤ by GitHub

2) You use the ISendEndpointprovider to specify a queue:

	var endpoint = await hub.GetSendEndpoint("rabbitmq://localhost:32778/sample_queue");
	await endpoint.Send(new ProcessSampleCommand());

view raw MassTransitSendEndpoint.cs hosted with ❤ by GitHub