Message Bus

MessageBus<TPayload> provides a typed in-process topic bus over MessageChannel<TPayload> subscribers. Use it when an application needs one integration surface for publishing domain or integration events to multiple internal consumers without coupling publishers to channel instances.

var bus = MessageBus<OrderEvent>.Create("order-bus")
    .Route("accepted", fulfillmentChannel)
    .Route("accepted", auditChannel)
    .Route("paid", billingChannel)
    .Build();

var result = bus.Publish("accepted", Message<OrderEvent>.Create(orderAccepted));

The fluent path supports runtime Subscribe(topic, channel) calls, so host bootstrapping can add tenant, module, or feature-specific routes from normal IServiceCollection registrations.

The source-generated path uses [GenerateMessageBus] and [MessageBusRoute] to create a strongly typed topology factory:

[GenerateMessageBus(typeof(OrderEvent), BusName = "order-bus")]
public static partial class GeneratedOrderBus
{
    [MessageBusRoute("accepted")]
    private static MessageChannel<OrderEvent> Accepted()
        => MessageChannel<OrderEvent>.Create("accepted-orders").Build();
}

OrderMessageBusExample demonstrates fluent and generated publishing. Import it with AddOrderMessageBusDemo() or the aggregate AddPatternKitExamples() registration.