Merge pull request #22134 from abpframework/LocalDistributedEventBus

[rel-9.1] Changes to make LocalDistributedEventBus able to use outbox/inbox patterns.

framework/src/Volo.Abp.AspNetCore.Mvc.Dapr.EventBus/Volo/Abp/AspNetCore/Mvc/Dapr/EventBus/AbpAspNetCoreMvcDaprEventBusModule.cs

@@ -97,13 +97,21 @@ public class AbpAspNetCoreMvcDaprEventBusModule : AbpModule
         if (IsAbpDaprEventData(data))
         {
             var daprEventData = daprSerializer.Deserialize(data, typeof(AbpDaprEventData)).As<AbpDaprEventData>();
-            var eventData = daprSerializer.Deserialize(daprEventData.JsonData, distributedEventBus.GetEventType(daprEventData.Topic));
-            await distributedEventBus.TriggerHandlersAsync(distributedEventBus.GetEventType(daprEventData.Topic), eventData, daprEventData.MessageId, daprEventData.CorrelationId);
+            var eventType = distributedEventBus.GetEventType(daprEventData.Topic);
+            if (eventType != null)
+            {
+                var eventData = daprSerializer.Deserialize(daprEventData.JsonData, eventType);
+                await distributedEventBus.TriggerHandlersAsync(eventType, eventData, daprEventData.MessageId, daprEventData.CorrelationId);
+            }
         }
         else
         {
-            var eventData = daprSerializer.Deserialize(data, distributedEventBus.GetEventType(topic!));
-            await distributedEventBus.TriggerHandlersAsync(distributedEventBus.GetEventType(topic!), eventData);
+            var eventType = distributedEventBus.GetEventType(topic);
+            if (eventType != null)
+            {
+                var eventData = daprSerializer.Deserialize(data, eventType);
+                await distributedEventBus.TriggerHandlersAsync(eventType, eventData);
+            }
         }
 
         httpContext.Response.StatusCode = 200;

framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/EventTypeWithEventHandlerFactories.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+
+namespace Volo.Abp.EventBus;
+
+public class EventTypeWithEventHandlerFactories
+{
+    public Type EventType { get; }
+
+    public List<IEventHandlerFactory> EventHandlerFactories { get; }
+
+    public EventTypeWithEventHandlerFactories(Type eventType, List<IEventHandlerFactory> eventHandlerFactories)
+    {
+        EventType = eventType;
+        EventHandlerFactories = eventHandlerFactories;
+    }
+}

framework/src/Volo.Abp.EventBus.Abstractions/Volo/Abp/EventBus/Local/ILocalEventBus.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace Volo.Abp.EventBus.Local;
 
@@ -8,11 +9,18 @@ namespace Volo.Abp.EventBus.Local;
 public interface ILocalEventBus : IEventBus
 {
     /// <summary>
-    /// Registers to an event. 
+    /// Registers to an event.
     /// Same (given) instance of the handler is used for all event occurrences.
     /// </summary>
     /// <typeparam name="TEvent">Event type</typeparam>
     /// <param name="handler">Object to handle the event</param>
     IDisposable Subscribe<TEvent>(ILocalEventHandler<TEvent> handler)
         where TEvent : class;
+
+    /// <summary>
+    /// Gets the list of event handler factories for the given event type.
+    /// </summary>
+    /// <param name="eventType">Event type</param>
+    /// <returns></returns>
+     List<EventTypeWithEventHandlerFactories> GetEventHandlerFactories(Type eventType);
 }

framework/src/Volo.Abp.EventBus.Dapr/Volo/Abp/EventBus/Dapr/DaprDistributedEventBus.cs

@@ -153,7 +153,13 @@ public class DaprDistributedEventBus : DistributedEventBusBase, ISingletonDepend
 
     public async override Task PublishFromOutboxAsync(OutgoingEventInfo outgoingEvent, OutboxConfig outboxConfig)
     {
-        await PublishToDaprAsync(outgoingEvent.EventName, Serializer.Deserialize(outgoingEvent.EventData, GetEventType(outgoingEvent.EventName)), outgoingEvent.Id, outgoingEvent.GetCorrelationId());
+        var eventType = GetEventType(outgoingEvent.EventName);
+        if (eventType == null)
+        {
+            return;
+        }
+
+        await PublishToDaprAsync(outgoingEvent.EventName, Serializer.Deserialize(outgoingEvent.EventData, eventType), outgoingEvent.Id, outgoingEvent.GetCorrelationId());
 
         using (CorrelationIdProvider.Change(outgoingEvent.GetCorrelationId()))
         {
@@ -168,21 +174,9 @@ public class DaprDistributedEventBus : DistributedEventBusBase, ISingletonDepend
 
     public async override Task PublishManyFromOutboxAsync(IEnumerable<OutgoingEventInfo> outgoingEvents, OutboxConfig outboxConfig)
     {
-        var outgoingEventArray = outgoingEvents.ToArray();
-
-        foreach (var outgoingEvent in outgoingEventArray)
+        foreach (var outgoingEvent in outgoingEvents)
         {
-            await PublishToDaprAsync(outgoingEvent.EventName, Serializer.Deserialize(outgoingEvent.EventData, GetEventType(outgoingEvent.EventName)), outgoingEvent.Id, outgoingEvent.GetCorrelationId());
-
-            using (CorrelationIdProvider.Change(outgoingEvent.GetCorrelationId()))
-            {
-                await TriggerDistributedEventSentAsync(new DistributedEventSent()
-                {
-                    Source = DistributedEventSource.Outbox,
-                    EventName = outgoingEvent.EventName,
-                    EventData = outgoingEvent.EventData
-                });
-            }
+           await PublishFromOutboxAsync(outgoingEvent, outboxConfig);
         }
     }
 
@@ -201,7 +195,7 @@ public class DaprDistributedEventBus : DistributedEventBusBase, ISingletonDepend
 
     public async override Task ProcessFromInboxAsync(IncomingEventInfo incomingEvent, InboxConfig inboxConfig)
     {
-        var eventType = EventTypes.GetOrDefault(incomingEvent.EventName);
+        var eventType = GetEventType(incomingEvent.EventName);
         if (eventType == null)
         {
             return;
@@ -243,9 +237,9 @@ public class DaprDistributedEventBus : DistributedEventBusBase, ISingletonDepend
         );
     }
 
-    public Type GetEventType(string eventName)
+    public Type? GetEventType(string eventName)
     {
-        return EventTypes.GetOrDefault(eventName)!;
+        return EventTypes.GetOrDefault(eventName);
     }
 
     protected virtual async Task PublishToDaprAsync(Type eventType, object eventData, Guid? messageId = null, string? correlationId = null)

framework/src/Volo.Abp.EventBus.Rebus/Volo/Abp/EventBus/Rebus/RebusDistributedEventBus.cs

@@ -250,7 +250,12 @@ public class RebusDistributedEventBus : DistributedEventBusBase, ISingletonDepen
         OutgoingEventInfo outgoingEvent,
         OutboxConfig outboxConfig)
     {
-        var eventType = EventTypes.GetOrDefault(outgoingEvent.EventName)!;
+        var eventType = EventTypes.GetOrDefault(outgoingEvent.EventName);
+        if (eventType == null)
+        {
+            return;
+        }
+
         var eventData = Serializer.Deserialize(outgoingEvent.EventData, eventType);
 
         var headers = new Dictionary<string, string>();

framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Distributed/DistributedEventBusBase.cs

@@ -62,7 +62,7 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
         return PublishAsync(typeof(TEvent), eventData, onUnitOfWorkComplete, useOutbox);
     }
 
-    public async Task PublishAsync(
+    public virtual async Task PublishAsync(
         Type eventType,
         object eventData,
         bool onUnitOfWorkComplete = true,
@@ -117,6 +117,8 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
             return false;
         }
 
+        var addedToOutbox = false;
+
         foreach (var outboxConfig in AbpDistributedEventBusOptions.Outboxes.Values.OrderBy(x => x.Selector is null))
         {
             if (outboxConfig.Selector == null || outboxConfig.Selector(eventType))
@@ -140,11 +142,11 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
                 }
 
                 await eventOutbox.EnqueueAsync(outgoingEventInfo);
-                return true;
+                addedToOutbox = true;
             }
         }
 
-        return false;
+        return addedToOutbox;
     }
 
     protected virtual Task OnAddToOutboxAsync(string eventName, Type eventType, object eventData)
@@ -164,6 +166,8 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
             return false;
         }
 
+        var addToInbox = false;
+
         using (var scope = ServiceScopeFactory.CreateScope())
         {
             foreach (var inboxConfig in AbpDistributedEventBusOptions.Inboxes.Values.OrderBy(x => x.EventSelector is null))
@@ -190,11 +194,12 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
                     );
                     incomingEventInfo.SetCorrelationId(correlationId!);
                     await eventInbox.EnqueueAsync(incomingEventInfo);
+                    addToInbox = true;
                 }
             }
         }
 
-        return true;
+        return addToInbox;
     }
 
     protected abstract byte[] Serialize(object eventData);
@@ -227,7 +232,7 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
     {
         try
         {
-            await LocalEventBus.PublishAsync(distributedEvent);
+            await LocalEventBus.PublishAsync(distributedEvent, onUnitOfWorkComplete: false);
         }
         catch (Exception)
         {
@@ -239,7 +244,7 @@ public abstract class DistributedEventBusBase : EventBusBase, IDistributedEventB
     {
         try
         {
-            await LocalEventBus.PublishAsync(distributedEvent);
+            await LocalEventBus.PublishAsync(distributedEvent, false);
         }
         catch (Exception)
         {

framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Distributed/LocalDistributedEventBus.cs

@@ -1,33 +1,53 @@
 using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
 using System.Reflection;
+using System.Text;
+using System.Text.Json;
+using System.Text.Unicode;
 using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Volo.Abp.Collections;
 using Volo.Abp.DependencyInjection;
 using Volo.Abp.EventBus.Local;
+using Volo.Abp.Guids;
+using Volo.Abp.MultiTenancy;
+using Volo.Abp.Timing;
+using Volo.Abp.Tracing;
+using Volo.Abp.Uow;
 
 namespace Volo.Abp.EventBus.Distributed;
 
 [Dependency(TryRegister = true)]
 [ExposeServices(typeof(IDistributedEventBus), typeof(LocalDistributedEventBus))]
-public class LocalDistributedEventBus : IDistributedEventBus, ISingletonDependency
+public class LocalDistributedEventBus : DistributedEventBusBase, ISingletonDependency
 {
-    private readonly ILocalEventBus _localEventBus;
-
-    protected IServiceScopeFactory ServiceScopeFactory { get; }
-
-    protected AbpDistributedEventBusOptions AbpDistributedEventBusOptions { get; }
+    protected ConcurrentDictionary<string, Type> EventTypes { get; }
 
     public LocalDistributedEventBus(
-        ILocalEventBus localEventBus,
         IServiceScopeFactory serviceScopeFactory,
-        IOptions<AbpDistributedEventBusOptions> distributedEventBusOptions)
+        ICurrentTenant currentTenant,
+        IUnitOfWorkManager unitOfWorkManager,
+        IOptions<AbpDistributedEventBusOptions> abpDistributedEventBusOptions,
+        IGuidGenerator guidGenerator,
+        IClock clock,
+        IEventHandlerInvoker eventHandlerInvoker,
+        ILocalEventBus localEventBus,
+        ICorrelationIdProvider correlationIdProvider)
+        : base(serviceScopeFactory,
+            currentTenant,
+            unitOfWorkManager,
+            abpDistributedEventBusOptions,
+            guidGenerator,
+            clock,
+            eventHandlerInvoker,
+            localEventBus,
+            correlationIdProvider)
     {
-        _localEventBus = localEventBus;
-        ServiceScopeFactory = serviceScopeFactory;
-        AbpDistributedEventBusOptions = distributedEventBusOptions.Value;
-        Subscribe(distributedEventBusOptions.Value.Handlers);
+        EventTypes = new ConcurrentDictionary<string, Type>();
+        Subscribe(abpDistributedEventBusOptions.Value.Handlers);
     }
 
     public virtual void Subscribe(ITypeList<IEventHandler> handlers)
@@ -51,122 +71,156 @@ public class LocalDistributedEventBus : IDistributedEventBus, ISingletonDependen
         }
     }
 
-    /// <inheritdoc/>
-    public virtual IDisposable Subscribe<TEvent>(IDistributedEventHandler<TEvent> handler) where TEvent : class
+    public override IDisposable Subscribe(Type eventType, IEventHandlerFactory factory)
     {
-        return Subscribe(typeof(TEvent), handler);
+        var eventName = EventNameAttribute.GetNameOrDefault(eventType);
+        EventTypes.GetOrAdd(eventName, eventType);
+        return LocalEventBus.Subscribe(eventType, factory);
     }
 
-    public IDisposable Subscribe<TEvent>(Func<TEvent, Task> action) where TEvent : class
+    public override void Unsubscribe<TEvent>(Func<TEvent, Task> action)
     {
-        return _localEventBus.Subscribe(action);
+        LocalEventBus.Unsubscribe(action);
     }
 
-    public IDisposable Subscribe<TEvent>(ILocalEventHandler<TEvent> handler) where TEvent : class
+    public override void Unsubscribe(Type eventType, IEventHandler handler)
     {
-        return _localEventBus.Subscribe(handler);
+        LocalEventBus.Unsubscribe(eventType, handler);
     }
 
-    public IDisposable Subscribe<TEvent, THandler>() where TEvent : class where THandler : IEventHandler, new()
+    public override void Unsubscribe(Type eventType, IEventHandlerFactory factory)
     {
-        return _localEventBus.Subscribe<TEvent, THandler>();
+        LocalEventBus.Unsubscribe(eventType, factory);
     }
 
-    public IDisposable Subscribe(Type eventType, IEventHandler handler)
+    public override void UnsubscribeAll(Type eventType)
     {
-        return _localEventBus.Subscribe(eventType, handler);
+        LocalEventBus.UnsubscribeAll(eventType);
     }
 
-    public IDisposable Subscribe<TEvent>(IEventHandlerFactory factory) where TEvent : class
+    public async override Task PublishAsync(Type eventType, object eventData, bool onUnitOfWorkComplete = true, bool useOutbox = true)
     {
-        return _localEventBus.Subscribe<TEvent>(factory);
-    }
+        if (onUnitOfWorkComplete && UnitOfWorkManager.Current != null)
+        {
+            AddToUnitOfWork(
+                UnitOfWorkManager.Current,
+                new UnitOfWorkEventRecord(eventType, eventData, EventOrderGenerator.GetNext(), useOutbox)
+            );
+            return;
+        }
 
-    public IDisposable Subscribe(Type eventType, IEventHandlerFactory factory)
-    {
-        return _localEventBus.Subscribe(eventType, factory);
-    }
+        if (useOutbox)
+        {
+            if (await AddToOutboxAsync(eventType, eventData))
+            {
+                return;
+            }
+        }
 
-    public void Unsubscribe<TEvent>(Func<TEvent, Task> action) where TEvent : class
-    {
-        _localEventBus.Unsubscribe(action);
-    }
+        await TriggerDistributedEventSentAsync(new DistributedEventSent()
+        {
+            Source = DistributedEventSource.Direct,
+            EventName = EventNameAttribute.GetNameOrDefault(eventType),
+            EventData = eventData
+        });
 
-    public void Unsubscribe<TEvent>(ILocalEventHandler<TEvent> handler) where TEvent : class
-    {
-        _localEventBus.Unsubscribe(handler);
-    }
+        await TriggerDistributedEventReceivedAsync(new DistributedEventReceived
+        {
+            Source = DistributedEventSource.Direct,
+            EventName = EventNameAttribute.GetNameOrDefault(eventType),
+            EventData = eventData
+        });
 
-    public void Unsubscribe(Type eventType, IEventHandler handler)
-    {
-        _localEventBus.Unsubscribe(eventType, handler);
+        await PublishToEventBusAsync(eventType, eventData);
     }
 
-    public void Unsubscribe<TEvent>(IEventHandlerFactory factory) where TEvent : class
+    protected async override Task PublishToEventBusAsync(Type eventType, object eventData)
     {
-        _localEventBus.Unsubscribe<TEvent>(factory);
-    }
+        if (await AddToInboxAsync(Guid.NewGuid().ToString(), EventNameAttribute.GetNameOrDefault(eventType), eventType, eventData, null))
+        {
+            return;
+        }
 
-    public void Unsubscribe(Type eventType, IEventHandlerFactory factory)
-    {
-        _localEventBus.Unsubscribe(eventType, factory);
+        await LocalEventBus.PublishAsync(eventType, eventData, false);
     }
 
-    public void UnsubscribeAll<TEvent>() where TEvent : class
+    protected override void AddToUnitOfWork(IUnitOfWork unitOfWork, UnitOfWorkEventRecord eventRecord)
     {
-        _localEventBus.UnsubscribeAll<TEvent>();
+        unitOfWork.AddOrReplaceDistributedEvent(eventRecord);
     }
 
-    public void UnsubscribeAll(Type eventType)
+    public async override Task PublishFromOutboxAsync(OutgoingEventInfo outgoingEvent, OutboxConfig outboxConfig)
     {
-        _localEventBus.UnsubscribeAll(eventType);
+        await TriggerDistributedEventSentAsync(new DistributedEventSent()
+        {
+            Source = DistributedEventSource.Outbox,
+            EventName = outgoingEvent.EventName,
+            EventData = outgoingEvent.EventData
+        });
+
+        await TriggerDistributedEventReceivedAsync(new DistributedEventReceived
+        {
+            Source = DistributedEventSource.Direct,
+            EventName = outgoingEvent.EventName,
+            EventData = outgoingEvent.EventData
+        });
+
+        var eventType = EventTypes.GetOrDefault(outgoingEvent.EventName);
+        if (eventType == null)
+        {
+            return;
+        }
+
+        var eventData = JsonSerializer.Deserialize(Encoding.UTF8.GetString(outgoingEvent.EventData), eventType)!;
+        if (await AddToInboxAsync(Guid.NewGuid().ToString(), outgoingEvent.EventName, eventType, eventData, null))
+        {
+            return;
+        }
+
+        await LocalEventBus.PublishAsync(eventType, eventData, false);
     }
 
-    public async Task PublishAsync<TEvent>(TEvent eventData, bool onUnitOfWorkComplete = true)
-        where TEvent : class
+    public async override Task PublishManyFromOutboxAsync(IEnumerable<OutgoingEventInfo> outgoingEvents, OutboxConfig outboxConfig)
     {
-        await PublishDistributedEventSentReceivedAsync(typeof(TEvent), eventData, onUnitOfWorkComplete);
-        await _localEventBus.PublishAsync(eventData, onUnitOfWorkComplete);
+        foreach (var outgoingEvent in outgoingEvents)
+        {
+            await PublishFromOutboxAsync(outgoingEvent, outboxConfig);
+        }
     }
 
-    public async Task PublishAsync(Type eventType, object eventData, bool onUnitOfWorkComplete = true)
+    public async override Task ProcessFromInboxAsync(IncomingEventInfo incomingEvent, InboxConfig inboxConfig)
     {
-        await PublishDistributedEventSentReceivedAsync(eventType, eventData, onUnitOfWorkComplete);
-        await _localEventBus.PublishAsync(eventType, eventData, onUnitOfWorkComplete);
+        var eventType = EventTypes.GetOrDefault(incomingEvent.EventName);
+        if (eventType == null)
+        {
+            return;
+        }
+
+        var eventData = JsonSerializer.Deserialize(incomingEvent.EventData, eventType);
+        var exceptions = new List<Exception>();
+        using (CorrelationIdProvider.Change(incomingEvent.GetCorrelationId()))
+        {
+            await TriggerHandlersFromInboxAsync(eventType, eventData!, exceptions, inboxConfig);
+        }
+        if (exceptions.Any())
+        {
+            ThrowOriginalExceptions(eventType, exceptions);
+        }
     }
 
-    public async Task PublishAsync<TEvent>(TEvent eventData, bool onUnitOfWorkComplete = true, bool useOutbox = true) where TEvent : class
+    protected override byte[] Serialize(object eventData)
     {
-        await PublishDistributedEventSentReceivedAsync(typeof(TEvent), eventData, onUnitOfWorkComplete);
-        await _localEventBus.PublishAsync(eventData, onUnitOfWorkComplete);
+        return Encoding.UTF8.GetBytes(JsonSerializer.Serialize(eventData));
     }
 
-    public async Task PublishAsync(Type eventType, object eventData, bool onUnitOfWorkComplete = true, bool useOutbox = true)
+    protected override Task OnAddToOutboxAsync(string eventName, Type eventType, object eventData)
     {
-        await PublishDistributedEventSentReceivedAsync(eventType, eventData, onUnitOfWorkComplete);
-        await _localEventBus.PublishAsync(eventType, eventData, onUnitOfWorkComplete);
+        EventTypes.GetOrAdd(eventName, eventType);
+        return base.OnAddToOutboxAsync(eventName, eventType, eventData);
     }
 
-    private async Task PublishDistributedEventSentReceivedAsync(Type eventType, object eventData, bool onUnitOfWorkComplete)
+    protected override IEnumerable<EventTypeWithEventHandlerFactories> GetHandlerFactories(Type eventType)
     {
-        if (eventType != typeof(DistributedEventSent))
-        {
-            await _localEventBus.PublishAsync(new DistributedEventSent
-            {
-                Source = DistributedEventSource.Direct,
-                EventName = EventNameAttribute.GetNameOrDefault(eventType),
-                EventData = eventData
-            }, onUnitOfWorkComplete);
-        }
-
-        if (eventType != typeof(DistributedEventReceived))
-        {
-            await _localEventBus.PublishAsync(new DistributedEventReceived
-            {
-                Source = DistributedEventSource.Direct,
-                EventName = EventNameAttribute.GetNameOrDefault(eventType),
-                EventData = eventData
-            }, onUnitOfWorkComplete);
-        }
+        return LocalEventBus.GetEventHandlerFactories(eventType);
     }
-}
+}

framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/EventBusBase.cs

@@ -242,19 +242,6 @@ public abstract class EventBusBase : IEventBus
         };
     }
 
-    protected class EventTypeWithEventHandlerFactories
-    {
-        public Type EventType { get; }
-
-        public List<IEventHandlerFactory> EventHandlerFactories { get; }
-
-        public EventTypeWithEventHandlerFactories(Type eventType, List<IEventHandlerFactory> eventHandlerFactories)
-        {
-            EventType = eventType;
-            EventHandlerFactories = eventHandlerFactories;
-        }
-    }
-
     // Reference from
     // https://blogs.msdn.microsoft.com/benwilli/2017/02/09/an-alternative-to-configureawaitfalse-everywhere/
     protected struct SynchronizationContextRemover : INotifyCompletion

framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Local/LocalEventBus.cs

@@ -136,6 +136,11 @@ public class LocalEventBus : EventBusBase, ILocalEventBus, ISingletonDependency
         await TriggerHandlersAsync(localEventMessage.EventType, localEventMessage.EventData);
     }
 
+    public virtual List<EventTypeWithEventHandlerFactories> GetEventHandlerFactories(Type eventType)
+    {
+        return GetHandlerFactories(eventType).ToList();
+    }
+
     protected override IEnumerable<EventTypeWithEventHandlerFactories> GetHandlerFactories(Type eventType)
     {
         var handlerFactoryList = new List<Tuple<IEventHandlerFactory, Type, int>>();

framework/src/Volo.Abp.EventBus/Volo/Abp/EventBus/Local/NullLocalEventBus.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 
 namespace Volo.Abp.EventBus.Local;
@@ -22,6 +23,11 @@ public sealed class NullLocalEventBus : ILocalEventBus
         return NullDisposable.Instance;
     }
 
+    public List<EventTypeWithEventHandlerFactories> GetEventHandlerFactories(Type eventType)
+    {
+        return new List<EventTypeWithEventHandlerFactories>();
+    }
+
     public IDisposable Subscribe<TEvent, THandler>() where TEvent : class where THandler : IEventHandler, new()
     {
         return NullDisposable.Instance;