Integrating with other systems

Often people want to consume messages off of their broker that are coming from other non-MassTransit systems. The below video reviews how to do this.

Key Points

Exclude this endpoint from the topology mapping. Since this endpoint is defined by a different system, we don't need MassTransit's help here.

endpointConfigurator.ConfigureConsumeTopology = false;

Add the RawJsonSerializer to the list of serializers supported. The serializer specifically looks for application/json versus the standard content-type used by MassTransit which is application/vnd.masstransit+json.

endpointConfigurator.UseRawJsonDeserializer();

If you want to have MT bind the endpoint to the correct topic you can do the following:

if(endpointConfigurator is IRabbitMqReceiveEndpointConfigurator rabbit) 
{
    rabbit.Bind("your-target-topic");
}

If the existing system isn't setting the content type

If the messages doesn't have a content-type set, you can tell MassTransit what the default content type should be. Since, as the app developer, you know the content is application/json you can set that manually. Then when a message comes in without a header, MT will select the correct one.

endpointConfigurator.DefaultContentType = new ContentType("application/json");
endpointConfigurator.UseRawJsonDeserializer();