feature: Subscribing to domain events via delegate

src/Backend.Fx/Patterns/EventAggregation/EventAggregator.cs

@@ -37,6 +37,19 @@ public EventAggregator(IEventHandlerProvider eventHandlerProvider)
                     throw;
                 }
             }
+
+            foreach (var subscribedHandler in subscribedEventHandlers.OfType<Action<TDomainEvent>>().ToArray())
+            {
+                try
+                {
+                    subscribedHandler.Invoke(domainEvent);
+                }
+                catch (Exception ex)
+                {
+                    Logger.Error(ex, $"Handling of {typeof(TDomainEvent).Name} by a subscribed handler failed.");
+                    throw;
+                }
+            }
         }
 
         /// <summary>
@@ -73,5 +86,15 @@ public EventAggregator(IEventHandlerProvider eventHandlerProvider)
         {
             subscribedEventHandlers.Add(handler);
         }
+
+        /// <summary>
+        /// Register a delegate that should be called synchronously in the same scope/transaction where the domain event is published.
+        /// </summary>
+        /// <typeparam name="TDomainEvent"></typeparam>
+        /// <param name="handler"></param>
+        public void SubscribeToDomainEvent<TDomainEvent>(Action<TDomainEvent> handler) where TDomainEvent : IDomainEvent
+        {
+            subscribedEventHandlers.Add(handler);
+        }
     }
 }

src/Backend.Fx/Patterns/EventAggregation/IEventHandlerProvider.cs

@@ -5,7 +5,7 @@ namespace Backend.Fx.Patterns.EventAggregation
     public interface IEventHandlerProvider
     {
         /// <summary>
-        /// get all deomain event handlers that want to handle a specific domain event
+        /// get all domain event handlers that want to handle a specific domain event
         /// </summary>
         /// <typeparam name="TDomainEvent"></typeparam>
         /// <returns></returns>