Pipelines

Toolkit.Foundation/AsyncHandlerDelegate.cs

@@ -0,0 +1,3 @@
+namespace Toolkit.Foundation;
+
+public delegate Task<TResponse> AsyncHandlerDelegate<TResponse>();

Toolkit.Foundation/AsyncHandlerInitialization.cs

@@ -5,19 +5,35 @@ namespace Toolkit.Foundation;
 
 public class AsyncHandlerInitialization<TMessage, TResponse, THandler>(IServiceProvider provider) :
     IInitialization where THandler : class, IAsyncHandler<TMessage, TResponse>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
         if (!StrongReferenceMessenger.Default.IsRegistered<AsyncResponseEventArgs<TMessage, TResponse>>(provider))
         {
             StrongReferenceMessenger.Default.Register<IServiceProvider, AsyncResponseEventArgs<TMessage, TResponse>>(provider,
-                (provider, args) =>
+                async (provider, args) =>
                 {
-                    foreach (IAsyncHandler<TMessage, TResponse> handler in provider.GetServices<IAsyncHandler<TMessage, TResponse>>())
+                    IEnumerable<IAsyncHandler<TMessage, TResponse>> handlers = provider.GetServices<IAsyncHandler<TMessage, TResponse>>();
+                    IEnumerable<IAsyncPipelineBehavior<TMessage, TResponse>> behaviors = provider.GetServices<IAsyncPipelineBehavior<TMessage, TResponse>>();
+
+                    AsyncHandlerDelegate<TResponse> handlerDelegate = async () =>
                     {
-                        args.Reply(handler.Handle(args.Message, args.CancellationToken));
+                        TResponse response = default!;
+                        foreach (IAsyncHandler<TMessage, TResponse> handler in handlers)
+                        {
+                            response = await handler.Handle(args.Message, args.CancellationToken);
+                        }
+                        return response;
+                    };
+
+                    foreach (IAsyncPipelineBehavior<TMessage, TResponse> behavior in behaviors.Reverse())
+                    {
+                        AsyncHandlerDelegate<TResponse> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args.Message, next);
                     }
+
+                    args.Reply(await handlerDelegate());
                 });
         }
     }
@@ -25,20 +41,35 @@ public class AsyncHandlerInitialization<TMessage, TResponse, THandler>(IServiceP
 
 public class AsyncHandlerInitialization<TMessage, THandler>(IServiceProvider provider) :
     IInitialization where THandler : class, IAsyncHandler<TMessage>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
         if (!StrongReferenceMessenger.Default.IsRegistered<AsyncResponseEventArgs<TMessage, Unit>>(provider))
         {
             StrongReferenceMessenger.Default.Register<IServiceProvider, AsyncResponseEventArgs<TMessage, Unit>>(provider,
-                (provider, args) =>
+                async (provider, args) =>
                 {
-                    foreach (IAsyncHandler<TMessage> handler in provider.GetServices<IAsyncHandler<TMessage>>())
+                    IEnumerable<IAsyncHandler<TMessage>> handlers = provider.GetServices<IAsyncHandler<TMessage>>();
+                    IEnumerable<IAsyncPipelineBehavior<TMessage, Unit>> behaviors = provider.GetServices<IAsyncPipelineBehavior<TMessage, Unit>>();
+
+                    AsyncHandlerDelegate<Unit> handlerDelegate = async () =>
                     {
-                        handler.Handle(args.Message, args.CancellationToken);
+                        foreach (IAsyncHandler<TMessage> handler in handlers)
-                        args.Reply(Unit.Value);
+                        {
+                            await handler.Handle(args.Message, args.CancellationToken);
+                        }
+                        return Unit.Value;
+                    };
+
+                    foreach (IAsyncPipelineBehavior<TMessage, Unit> behavior in behaviors.Reverse())
+                    {
+                        AsyncHandlerDelegate<Unit> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args.Message, next);
                     }
+
+                    await handlerDelegate();
+                    args.Reply(Unit.Value);
                 });
         }
     }

Toolkit.Foundation/AsyncHandlerKeyedInitialization.cs

@@ -5,20 +5,35 @@ namespace Toolkit.Foundation;
 
 public class AsyncHandlerKeyedInitialization<TMessage, THandler>(string key, IServiceProvider provider) :
     IInitialization where THandler : class, IAsyncHandler<TMessage>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
         if (!StrongReferenceMessenger.Default.IsRegistered<AsyncResponseEventArgs<TMessage, Unit>, string>(provider, key))
         {
             StrongReferenceMessenger.Default.Register<IServiceProvider, AsyncResponseEventArgs<TMessage, Unit>, string>(provider, key,
-                (provider, args) =>
+                async (provider, args) =>
                 {
-                    foreach (IAsyncHandler<TMessage> handler in provider.GetKeyedServices<IAsyncHandler<TMessage>>(key))
+                    IEnumerable<IAsyncHandler<TMessage>> handlers = provider.GetKeyedServices<IAsyncHandler<TMessage>>(key);
+                    IEnumerable<IAsyncPipelineBehavior<TMessage, Unit>> behaviors = provider.GetServices<IAsyncPipelineBehavior<TMessage, Unit>>();
+
+                    AsyncHandlerDelegate<Unit> handlerDelegate = async () =>
                     {
-                        handler.Handle(args.Message, args.CancellationToken);
+                        foreach (IAsyncHandler<TMessage> handler in handlers)
-                        args.Reply(Unit.Value);
+                        {
+                            await handler.Handle(args.Message, args.CancellationToken);
+                        }
+                        return Unit.Value;
+                    };
+
+                    foreach (IAsyncPipelineBehavior<TMessage, Unit> behavior in behaviors.Reverse())
+                    {
+                        AsyncHandlerDelegate<Unit> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args.Message, next);
                     }
+
+                    await handlerDelegate();
+                    args.Reply(Unit.Value);
                 });
         }
     }
@@ -26,20 +41,36 @@ public class AsyncHandlerKeyedInitialization<TMessage, THandler>(string key, ISe
 
 public class AsyncHandlerKeyedInitialization<TMessage, TResponse, THandler>(string key, IServiceProvider provider) :
     IInitialization where THandler : class, IAsyncHandler<TMessage, TResponse>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
         if (!StrongReferenceMessenger.Default.IsRegistered<AsyncResponseEventArgs<TMessage, TResponse>, string>(provider, key))
         {
             StrongReferenceMessenger.Default.Register<IServiceProvider, AsyncResponseEventArgs<TMessage, TResponse>, string>(provider, key,
-                (provider, args) =>
+                async (provider, args) =>
                 {
-                    foreach (IAsyncHandler<TMessage, TResponse> handler in provider.GetKeyedServices<IAsyncHandler<TMessage, TResponse>>(key))
+                    IEnumerable<IAsyncHandler<TMessage, TResponse>> handlers = provider.GetKeyedServices<IAsyncHandler<TMessage, TResponse>>(key);
+                    IEnumerable<IAsyncPipelineBehavior<TMessage, TResponse>> behaviors = provider.GetServices<IAsyncPipelineBehavior<TMessage, TResponse>>();
+
+                    AsyncHandlerDelegate<TResponse> handlerDelegate = async () =>
                     {
-                        args.Reply(handler.Handle(args.Message, args.CancellationToken));
+                        TResponse response = default!;
+                        foreach (IAsyncHandler<TMessage, TResponse> handler in handlers)
+                        {
+                            response = await handler.Handle(args.Message, args.CancellationToken);
+                        }
+                        return response;
+                    };
+
+                    foreach (IAsyncPipelineBehavior<TMessage, TResponse> behavior in behaviors.Reverse())
+                    {
+                        AsyncHandlerDelegate<TResponse> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args.Message, next);
                     }
+
+                    args.Reply(await handlerDelegate());
                 });
         }
     }
-}
+}

Toolkit.Foundation/HandlerDelegate.cs

@@ -1,4 +1,3 @@
 namespace Toolkit.Foundation;
 
-public delegate Task<TResponse> HandlerDelegate<TRequest, TResponse>(TRequest request,
+public delegate TResponse HandlerDelegate<TResponse>();
-    CancellationToken cancellationToken);

Toolkit.Foundation/HandlerInitialization.cs

@@ -5,7 +5,7 @@ namespace Toolkit.Foundation;
 
 public class HandlerInitialization<TMessage, TResponse, THandler>(IServiceProvider provider) :
     IInitialization where THandler : class, IHandler<TMessage, TResponse>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
@@ -14,10 +14,26 @@ public class HandlerInitialization<TMessage, TResponse, THandler>(IServiceProvid
             StrongReferenceMessenger.Default.Register<IServiceProvider, ResponseEventArgs<TMessage, TResponse>>(provider,
                 (provider, args) =>
                 {
-                    foreach (IHandler<TMessage, TResponse> handler in provider.GetServices<IHandler<TMessage, TResponse>>())
+                    IEnumerable<IHandler<TMessage, TResponse>> handlers = provider.GetServices<IHandler<TMessage, TResponse>>();
+                    IEnumerable<IPipelineBehavior<TMessage, TResponse>> behaviors = provider.GetServices<IPipelineBehavior<TMessage, TResponse>>();
+
+                    HandlerDelegate<TResponse> handlerDelegate = () =>
                     {
-                        handler.Handle(args.Message);
+                        TResponse response = default!;
+                        foreach (IHandler<TMessage, TResponse> handler in handlers)
+                        {
+                            response = handler.Handle(args.Message);
+                        }
+                        return response;
+                    };
+
+                    foreach (IPipelineBehavior<TMessage, TResponse> behavior in behaviors.Reverse())
+                    {
+                        HandlerDelegate<TResponse> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args.Message, next);
                     }
+
+                    handlerDelegate();
                 });
         }
     }
@@ -25,7 +41,7 @@ public class HandlerInitialization<TMessage, TResponse, THandler>(IServiceProvid
 
 public class HandlerInitialization<TMessage, THandler>(IServiceProvider provider) :
     IInitialization where THandler : class, IHandler<TMessage>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
@@ -34,11 +50,27 @@ public class HandlerInitialization<TMessage, THandler>(IServiceProvider provider
             StrongReferenceMessenger.Default.Register<IServiceProvider, TMessage>(provider,
                 (provider, args) =>
                 {
-                    foreach (IHandler<TMessage> handler in provider.GetServices<IHandler<TMessage>>())
+                    IEnumerable<IHandler<TMessage>> handlers = provider.GetServices<IHandler<TMessage>>();
+                    IEnumerable<IPipelineBehavior<TMessage, Unit>> behaviors = provider.GetServices<IPipelineBehavior<TMessage, Unit>>();
+
+                    HandlerDelegate<Unit> handlerDelegate = () =>
                     {
-                        handler.Handle(args);
+                        foreach (IHandler<TMessage> handler in handlers)
+                        {
+                            handler.Handle(args);
+                        }
+                        return Unit.Value;
+                    };
+
+                    foreach (IPipelineBehavior<TMessage, Unit> behavior in behaviors.Reverse())
+                    {
+                        HandlerDelegate<Unit> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args, next);
                     }
+
+                    handlerDelegate();
                 });
         }
     }
 }
+

Toolkit.Foundation/HandlerKeyedInitialization.cs

@@ -5,7 +5,7 @@ namespace Toolkit.Foundation;
 
 public class HandlerKeyedInitialization<TMessage, THandler>(string key, IServiceProvider provider) :
     IInitialization where THandler : class, IHandler<TMessage>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
@@ -14,18 +14,34 @@ public class HandlerKeyedInitialization<TMessage, THandler>(string key, IService
             StrongReferenceMessenger.Default.Register<IServiceProvider, TMessage, string>(provider, key,
                 (provider, args) =>
                 {
-                    foreach (IHandler<TMessage> handler in provider.GetKeyedServices<IHandler<TMessage>>(key))
+                    IEnumerable<IHandler<TMessage>> handlers = provider.GetKeyedServices<IHandler<TMessage>>(key);
+                    IEnumerable<IPipelineBehavior<TMessage, Unit>> behaviors = provider.GetServices<IPipelineBehavior<TMessage, Unit>>();
+
+                    HandlerDelegate<Unit> handlerDelegate = () =>
                     {
-                        handler.Handle(args);
+                        foreach (IHandler<TMessage> handler in handlers)
+                        {
+                            handler.Handle(args);
+                        }
+                        return Unit.Value;
+                    };
+
+                    foreach (IPipelineBehavior<TMessage, Unit> behavior in behaviors.Reverse())
+                    {
+                        HandlerDelegate<Unit> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args, next);
                     }
+
+                    handlerDelegate();
                 });
         }
     }
 }
 
+
 public class HandlerKeyedInitialization<TMessage, TResponse, THandler>(string key, IServiceProvider provider) :
     IInitialization where THandler : class, IHandler<TMessage, TResponse>
-        where TMessage : class
+    where TMessage : class
 {
     public void Initialize()
     {
@@ -34,11 +50,27 @@ public class HandlerKeyedInitialization<TMessage, TResponse, THandler>(string ke
             StrongReferenceMessenger.Default.Register<IServiceProvider, ResponseEventArgs<TMessage, TResponse>, string>(provider, key,
                 (provider, args) =>
                 {
-                    foreach (IHandler<TMessage, TResponse> handler in provider.GetKeyedServices<IHandler<TMessage, TResponse>>(key))
+                    IEnumerable<IHandler<TMessage, TResponse>> handlers = provider.GetKeyedServices<IHandler<TMessage, TResponse>>(key);
+                    IEnumerable<IPipelineBehavior<TMessage, TResponse>> behaviors = provider.GetServices<IPipelineBehavior<TMessage, TResponse>>();
+
+                    HandlerDelegate<TResponse> handlerDelegate = () =>
                     {
-                        handler.Handle(args.Message);
+                        TResponse response = default!;
+                        foreach (IHandler<TMessage, TResponse> handler in handlers)
+                        {
+                            response = handler.Handle(args.Message);
+                        }
+                        return response;
+                    };
+
+                    foreach (IPipelineBehavior<TMessage, TResponse> behavior in behaviors.Reverse())
+                    {
+                        HandlerDelegate<TResponse> next = handlerDelegate;
+                        handlerDelegate = () => behavior.Handle(args.Message, next);
                     }
+
+                    handlerDelegate();
                 });
         }
     }
-}
+}

Toolkit.Foundation/IAsyncPipelineBehavior.cs

@@ -0,0 +1,8 @@
+namespace Toolkit.Foundation;
+
+public interface IAsyncPipelineBehavior<TMessage,
+    TResponse>
+{
+    Task<TResponse> Handle(TMessage message, 
+        AsyncHandlerDelegate<TResponse> next);
+}

Toolkit.Foundation/IPipelineBehavior.cs

@@ -0,0 +1,9 @@
+namespace Toolkit.Foundation;
+
+public interface IPipelineBehavior<TMessage,
+    TResponse>
+{
+    TResponse Handle(TMessage message, 
+        HandlerDelegate<TResponse> next);
+}
+

Toolkit.Foundation/IServiceCollectionExtensions.cs

@@ -124,7 +124,7 @@ public static class IServiceCollectionExtensions
         where THandler : class, IHandler<TMessage>
         where TMessage : class
     {
-        if (key is { Length: > 0})
+        if (key is { Length: > 0 })
         {
             services.Add(new ServiceDescriptor(typeof(IHandler<TMessage>), key, typeof(THandler), lifetime));
             services.AddInitialization<HandlerKeyedInitialization<TMessage, IHandler<TMessage>>>(key);
@@ -158,7 +158,7 @@ public static class IServiceCollectionExtensions
         return services;
     }
 
-    public static IServiceCollection AddInitialization<TInitialization>(this IServiceCollection services, 
+    public static IServiceCollection AddInitialization<TInitialization>(this IServiceCollection services,
         params object[] parameters)
         where TInitialization : class,
         IInitialization
@@ -167,6 +167,22 @@ public static class IServiceCollectionExtensions
         return services;
     }
 
+    public static IServiceCollection AddAsyncPipelineBehavior<TMessage, TResponse, TBehavior>(this IServiceCollection services)
+        where TBehavior : class,
+        IAsyncPipelineBehavior<TMessage, TResponse>
+    {
+        services.AddTransient<IAsyncPipelineBehavior<TMessage, TResponse>, TBehavior>();
+        return services;
+    }
+
+    public static IServiceCollection AddPipelineBehavior<TMessage, TResponse, TBehavior>(this IServiceCollection services)
+        where TBehavior : class,
+        IPipelineBehavior<TMessage, TResponse>
+    {
+        services.AddTransient<IPipelineBehavior<TMessage, TResponse>, TBehavior>();
+        return services;
+    }
+
     public static IServiceCollection AddRange(this IServiceCollection services,
         IServiceCollection fromServices)
     {