New [AlwaysPublishResponse] attribute usage for selective, explicit backward compatibility with Wolverine <3 behavior

Author: jeremydmiller

Directory.Build.props

@@ -12,7 +12,7 @@
         <ImplicitUsings>true</ImplicitUsings>
         <Nullable>enable</Nullable>
         <VersionPrefix>3.0.0</VersionPrefix>
-        <VersionSuffix>alpha-3</VersionSuffix>
+        <VersionSuffix>beta-1</VersionSuffix>
         <RepositoryUrl>$(PackageProjectUrl)</RepositoryUrl>
         <PublishRepositoryUrl>true</PublishRepositoryUrl>
         <EmbedUntrackedSources>true</EmbedUntrackedSources>

docs/guide/messaging/message-bus.md

@@ -137,6 +137,11 @@ Note that if you execute the `Numbers` message from above with `InvokeAsync<Resu
 returned as the response and will not be published as a message. This was a breaking change in Wolverine 3.0. We think (hope)
 that this will be less confusing.
 
+You can explicitly override this behavior on a handler by handler basis with the `[AlwaysPublishResponse]` attribute
+as shown below:
+
+snippet: sample_using_AlwaysPublishResponse
+
 ## Sending or Publishing Messages
 
 [Publish/Subscribe](https://docs.microsoft.com/en-us/azure/architecture/patterns/publisher-subscriber) is a messaging pattern where the senders of messages do not need to specifically know what the specific subscribers are for a given message. In this case, some kind of middleware or infrastructure is responsible for either allowing subscribers to express interest in what messages they need to receive or apply routing rules to send the published messages to the right places. Wolverine's messaging support was largely built to support the publish/subscribe messaging pattern.

docs/guide/migration.md

@@ -50,4 +50,9 @@ Also for Wolverine.Http users, the `[Document]` attribute behavior in the Marten
 
 The behavior of `IMessageBus.InvokeAsync<T>(message)` changed in 3.0 such that the `T` response **is not also published as a 
 message** at the same time when the initial message is sent with request/response semantics. Wolverine has gone back and forth
-in this behavior in its life, but at this point, the Wolverine thinks that this is the least confusing behavioral rule. 
+in this behavior in its life, but at this point, the Wolverine thinks that this is the least confusing behavioral rule. 
+
+You can selectively override this behavior and tell Wolverine to publish the response as a message no matter what
+by using the new 3.0 `[AlwaysPublishResponse]` attribute like this:
+
+snippet: sample_using_AlwaysPublishResponse

src/Http/Wolverine.Http.Tests/mapping_routes_to_wolverine_handlers.cs

@@ -52,8 +52,6 @@ public async Task map_post_with_request_response()
         });
 
         result.ReadAsJson<CustomResponse>().Name.ShouldBe("Alan Alda");
-
-        tracked.Sent.SingleMessage<CustomResponse>();
     }
 
     [Fact]
@@ -65,8 +63,6 @@ public async Task map_put_with_request_response()
         });
 
         result.ReadAsJson<CustomResponse>().Name.ShouldBe("FDR");
-
-        tracked.Sent.SingleMessage<CustomResponse>();
     }
 
     [Fact]
@@ -78,7 +74,5 @@ public async Task map_delete_with_request_response()
         });
 
         result.ReadAsJson<CustomResponse>().Name.ShouldBe("LBJ");
-
-        tracked.Sent.SingleMessage<CustomResponse>();
     }
 }

src/Persistence/MartenTests/Bugs/Bug_305_invoke_async_with_return_not_publishing_with_tuple_return_value.cs

@@ -5,6 +5,7 @@
 using Wolverine.Marten;
 using Wolverine.Tracking;
 using Shouldly;
+using Wolverine.Attributes;
 
 namespace MartenTests.Bugs;
 
@@ -35,8 +36,13 @@ public class CreateItemCommand
     public string Name { get; set; } = string.Empty;
 }
 
+#region sample_using_AlwaysPublishResponse
+
 public class CreateItemCommandHandler
 {
+    // Using this attribute will force Wolverine to also publish the ItemCreated event even if
+    // this is called by IMessageBus.InvokeAsync<ItemCreated>()
+    [AlwaysPublishResponse]
     public async Task<(ItemCreated, SecondItemCreated)> Handle(CreateItemCommand command, IDocumentSession session)
     {
         var item = new Item
@@ -51,6 +57,8 @@ public class CreateItemCommandHandler
     }
 }
 
+#endregion
+
 public record ItemCreated(Guid Id, string Name);
 
 public record SecondItemCreated(Guid Id, string Name);

src/Persistence/MartenTests/aggregate_handler_workflow.cs

@@ -96,8 +96,6 @@ public async Task events_then_response_invoke_with_return()
         response.BCount.ShouldBe(1);
         response.CCount.ShouldBe(1);
 
-        tracked.Sent.SingleMessage<Response>().ACount.ShouldBe(1);
-
         await OnAggregate(a =>
         {
             a.ACount.ShouldBe(1);
@@ -131,8 +129,6 @@ [Fact] public async Task response_then_events_invoke_with_return()
         response.BCount.ShouldBe(1);
         response.CCount.ShouldBe(2);
 
-        tracked.Sent.SingleMessage<Response>().ACount.ShouldBe(2);
-
         await OnAggregate(a =>
         {
             a.ACount.ShouldBe(2);

src/Wolverine/Attributes/AlwaysPublishResponseAttribute.cs

@@ -0,0 +1,37 @@
+using JasperFx.CodeGeneration;
+using JasperFx.CodeGeneration.Frames;
+using JasperFx.CodeGeneration.Model;
+using Wolverine.Runtime.Handlers;
+
+namespace Wolverine.Attributes;
+
+/// <summary>
+/// Decorate any handler method or class if you always want any response
+/// (the "T" in IMessageBus.InvokeAsync<T>()) to be *also* published as a
+/// message in addition to being the response object
+/// </summary>
+public class AlwaysPublishResponseAttribute : ModifyHandlerChainAttribute
+{
+    public override void Modify(HandlerChain chain, GenerationRules rules)
+    {
+        chain.Middleware.Add(new AlwaysPublishResponseFrame());
+    }
+}
+
+internal class AlwaysPublishResponseFrame : SyncFrame
+{
+    private Variable _envelope;
+
+    public override void GenerateCode(GeneratedMethod method, ISourceWriter writer)
+    {
+        writer.WriteComment("Always publish the response as a message due to the [AlwaysPublishResponse] usage");
+        writer.WriteLine($"{_envelope.Usage}.{nameof(Envelope.DoNotCascadeResponse)} = false;");
+        Next?.GenerateCode(method, writer);
+    }
+
+    public override IEnumerable<Variable> FindVariables(IMethodVariables chain)
+    {
+        _envelope = chain.FindVariable(typeof(Envelope));
+        yield return _envelope;
+    }
+}

src/Wolverine/Envelope.Internals.cs

@@ -63,7 +63,7 @@ internal Envelope(object message, IMessageSerializer writer)
     /// message as a cascading message. Originally added for the
     /// Http transport request/reply
     /// </summary>
-    internal bool DoNotCascadeResponse { get; set; }
+    public bool DoNotCascadeResponse { get; set; }
 
     /// <summary>
     ///     Status according to the message persistence