Incremental work on proto actor and service bus

Elsa.sln

@@ -70,7 +70,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "modules", "modules", "{5BA4
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Modules.Quartz", "src\modules\Elsa.Modules.Quartz\Elsa.Modules.Quartz.csproj", "{7D5A49B4-9A9B-496E-803B-DEB85B2C3132}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Jobs", "src\core\Elsa.Jobs\Elsa.Jobs.csproj", "{50697882-E38B-4CE7-B041-8009C18490E0}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Jobs.Abstractions", "src\core\Elsa.Jobs.Abstractions\Elsa.Jobs.Abstractions.csproj", "{50697882-E38B-4CE7-B041-8009C18490E0}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Modules.Http", "src\modules\Elsa.Modules.Http\Elsa.Modules.Http.csproj", "{82E26BF9-5F3A-4365-899A-AB1FFD54AA45}"
 EndProject
@@ -90,6 +90,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Modules.SetName", "src
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Modules.Activities", "src\modules\Elsa.Modules.Activities\Elsa.Modules.Activities.csproj", "{05249066-9125-47D8-847B-A86887B1D269}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.ServiceBus.Abstractions", "src\core\Elsa.ServiceBus.Abstractions\Elsa.ServiceBus.Abstractions.csproj", "{61FAFEED-A477-4D8F-A293-C0196F11EA0F}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Elsa.Modules.MassTransit", "src\modules\Elsa.Modules.MassTransit\Elsa.Modules.MassTransit.csproj", "{BB983D0B-A939-4008-B9E3-C7C172BCF83A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -212,6 +216,14 @@ Global
 		{05249066-9125-47D8-847B-A86887B1D269}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{05249066-9125-47D8-847B-A86887B1D269}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{05249066-9125-47D8-847B-A86887B1D269}.Release|Any CPU.Build.0 = Release|Any CPU
+		{61FAFEED-A477-4D8F-A293-C0196F11EA0F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{61FAFEED-A477-4D8F-A293-C0196F11EA0F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{61FAFEED-A477-4D8F-A293-C0196F11EA0F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{61FAFEED-A477-4D8F-A293-C0196F11EA0F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{BB983D0B-A939-4008-B9E3-C7C172BCF83A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{BB983D0B-A939-4008-B9E3-C7C172BCF83A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{BB983D0B-A939-4008-B9E3-C7C172BCF83A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{BB983D0B-A939-4008-B9E3-C7C172BCF83A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{155227F0-A33B-40AA-A4B4-06F813EB921B} = {61017E64-6D00-49CB-9E81-5002DC8F7D5F}
@@ -254,5 +266,7 @@ Global
 		{302BFC43-ED2F-43AE-8AD4-FCD481B0AC67} = {5BA4A8FA-F7F4-45B3-AEC8-8886D35AAC79}
 		{E4EB94A0-E6F6-4EFA-BE55-7CEED1D8431A} = {5BA4A8FA-F7F4-45B3-AEC8-8886D35AAC79}
 		{05249066-9125-47D8-847B-A86887B1D269} = {5BA4A8FA-F7F4-45B3-AEC8-8886D35AAC79}
+		{61FAFEED-A477-4D8F-A293-C0196F11EA0F} = {C6658DE0-2B2F-47F0-BB61-2CA66D435C09}
+		{BB983D0B-A939-4008-B9E3-C7C172BCF83A} = {5BA4A8FA-F7F4-45B3-AEC8-8886D35AAC79}
 	EndGlobalSection
 EndGlobal

src/api/Elsa.Api/ApiResults/DispatchWorkflowResult.cs

@@ -17,9 +17,9 @@ public class DispatchWorkflowResult : IResult
     public async Task ExecuteAsync(HttpContext httpContext)
     {
         var response = httpContext.Response;
-        var workflowInvoker = httpContext.RequestServices.GetRequiredService<IWorkflowInvoker>();
+        var workflowDispatcher = httpContext.RequestServices.GetRequiredService<IWorkflowDispatcher>();
         var definitionId = Workflow.Identity.DefinitionId;
-        var result = await workflowInvoker.DispatchAsync(new DispatchWorkflowDefinitionRequest(definitionId, VersionOptions.Published));
+        var result = await workflowDispatcher.DispatchAsync(new DispatchWorkflowDefinitionRequest(definitionId, VersionOptions.Published));
 
         response.StatusCode = (int)HttpStatusCode.OK;
         await response.WriteAsJsonAsync(result, httpContext.RequestAborted);

src/api/Elsa.Api/ApiResults/ExecuteWorkflowResult.cs

@@ -19,8 +19,8 @@ public class ExecuteWorkflowResult : IResult
         var response = httpContext.Response;
         var workflowInvoker = httpContext.RequestServices.GetRequiredService<IWorkflowInvoker>();
         var definitionId = Workflow.Identity.DefinitionId;
-        var executeRequest = new ExecuteWorkflowDefinitionRequest(definitionId, VersionOptions.Published);
-        var result = await workflowInvoker.ExecuteAsync(executeRequest, CancellationToken.None);
+        var executeRequest = new InvokeWorkflowDefinitionRequest(definitionId, VersionOptions.Published);
+        var result = await workflowInvoker.InvokeAsync(executeRequest, CancellationToken.None);
 
         if (!response.HasStarted)
             await response.WriteAsJsonAsync(result, httpContext.RequestAborted);

src/core/Elsa.Core/Contracts/IWorkflowRunner.cs

@@ -5,8 +5,8 @@ namespace Elsa.Contracts;
 
 public interface IWorkflowRunner
 {
-    Task<ExecuteWorkflowResult> RunAsync(Workflow workflow, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
-    Task<ExecuteWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
-    Task<ExecuteWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, Bookmark? bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
-    Task<ExecuteWorkflowResult> RunAsync(WorkflowExecutionContext workflowExecutionContext);
+    Task<InvokeWorkflowResult> RunAsync(Workflow workflow, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<InvokeWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<InvokeWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, Bookmark? bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<InvokeWorkflowResult> RunAsync(WorkflowExecutionContext workflowExecutionContext);
 }

src/core/Elsa.Core/Models/DispatchWorkflowResult.cs

@@ -1,3 +0,0 @@
-namespace Elsa.Models;
-
-public record DispatchWorkflowResult();

src/core/Elsa.Core/Models/ExecuteWorkflowResult.cs

@@ -1,5 +0,0 @@
-using Elsa.State;
-
-namespace Elsa.Models;
-
-public record ExecuteWorkflowResult(WorkflowState WorkflowState, IReadOnlyCollection<Bookmark> Bookmarks);

src/core/Elsa.Core/Models/InvokeWorkflowResult.cs

@@ -0,0 +1,5 @@
+using Elsa.State;
+
+namespace Elsa.Models;
+
+public record InvokeWorkflowResult(WorkflowState WorkflowState, IReadOnlyCollection<Bookmark> Bookmarks);

src/core/Elsa.Core/Services/WorkflowRunner.cs

@@ -30,7 +30,7 @@ public class WorkflowRunner : IWorkflowRunner
         _schedulerFactory = schedulerFactory;
     }
 
-    public async Task<ExecuteWorkflowResult> RunAsync(Workflow workflow, IDictionary<string, object>? input, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> RunAsync(Workflow workflow, IDictionary<string, object>? input, CancellationToken cancellationToken = default)
     {
         // Create a child scope.
         using var scope = _serviceScopeFactory.CreateScope();
@@ -44,7 +44,7 @@ public class WorkflowRunner : IWorkflowRunner
         return await RunAsync(workflowExecutionContext);
     }
 
-    public async Task<ExecuteWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, IDictionary<string, object>? input, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, IDictionary<string, object>? input, CancellationToken cancellationToken = default)
     {
         // Create a child scope.
         using var scope = _serviceScopeFactory.CreateScope();
@@ -58,7 +58,7 @@ public class WorkflowRunner : IWorkflowRunner
         return await RunAsync(workflowExecutionContext);
     }
 
-    public async Task<ExecuteWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, Bookmark? bookmark, IDictionary<string, object>? input, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> RunAsync(Workflow workflow, WorkflowState workflowState, Bookmark? bookmark, IDictionary<string, object>? input, CancellationToken cancellationToken = default)
     {
         // Create a child scope.
         using var scope = _serviceScopeFactory.CreateScope();
@@ -72,7 +72,7 @@ public class WorkflowRunner : IWorkflowRunner
         return await RunAsync(workflowExecutionContext);
     }
 
-    public async Task<ExecuteWorkflowResult> RunAsync(WorkflowExecutionContext workflowExecutionContext)
+    public async Task<InvokeWorkflowResult> RunAsync(WorkflowExecutionContext workflowExecutionContext)
     {
         // Execute the activity execution pipeline.
         await _pipeline.ExecuteAsync(workflowExecutionContext);
@@ -81,7 +81,7 @@ public class WorkflowRunner : IWorkflowRunner
         var workflowState = _workflowStateSerializer.ReadState(workflowExecutionContext);
 
         // Return workflow execution result containing state + bookmarks.
-        return new ExecuteWorkflowResult(workflowState, workflowExecutionContext.Bookmarks);
+        return new InvokeWorkflowResult(workflowState, workflowExecutionContext.Bookmarks);
     }
 
     private WorkflowExecutionContext CreateWorkflowExecutionContext(

src/core/Elsa.Jobs.Abstractions/Elsa.Jobs.Abstractions.csproj

@@ -4,6 +4,7 @@
         <TargetFramework>net6.0</TargetFramework>
         <Nullable>enable</Nullable>
         <LangVersion>Latest</LangVersion>
+        <RootNamespace>Elsa.Jobs</RootNamespace>
     </PropertyGroup>
 
     <ItemGroup>

src/core/Elsa.ServiceBus.Abstractions/Contracts/IServiceBus.cs

@@ -0,0 +1,7 @@
+namespace Elsa.ServiceBus.Abstractions.Contracts;
+
+public interface IServiceBus
+{
+    Task SendAsync(object message, CancellationToken cancellationToken = default);
+    Task PublishAsync(object message, CancellationToken cancellationToken = default);
+}

src/core/Elsa.ServiceBus.Abstractions/Contracts/IServiceBusProvider.cs

@@ -0,0 +1,8 @@
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Elsa.ServiceBus.Abstractions.Contracts;
+
+public interface IServiceBusProvider
+{
+    void ConfigureServices(IServiceCollection services);
+}

src/core/Elsa.ServiceBus.Abstractions/Elsa.ServiceBus.Abstractions.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net6.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
+    </ItemGroup>
+
+</Project>

src/modules/Elsa.Modules.Activities/Elsa.Modules.Activities.csproj

@@ -7,7 +7,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <ProjectReference Include="..\..\core\Elsa.Jobs\Elsa.Jobs.csproj" />
+      <ProjectReference Include="..\..\core\Elsa.Jobs.Abstractions\Elsa.Jobs.Abstractions.csproj" />
       <ProjectReference Include="..\..\runtime\Elsa.Runtime\Elsa.Runtime.csproj" />
     </ItemGroup>
 

src/modules/Elsa.Modules.Hangfire/Elsa.Modules.Hangfire.csproj

@@ -11,7 +11,7 @@
     </ItemGroup>
 
     <ItemGroup>
-      <ProjectReference Include="..\..\core\Elsa.Jobs\Elsa.Jobs.csproj" />
+      <ProjectReference Include="..\..\core\Elsa.Jobs.Abstractions\Elsa.Jobs.Abstractions.csproj" />
     </ItemGroup>
 
 </Project>

src/modules/Elsa.Modules.Http/Middleware/HttpTriggerMiddleware.cs

@@ -53,7 +53,7 @@ public class HttpTriggerMiddleware
 
             var model = new
             {
-                workflowInstanceIds = executionResults.Select(x => x.ExecuteWorkflowResult.WorkflowState.Id).ToArray()
+                workflowInstanceIds = executionResults.Select(x => x.InvokeWorkflowResult.WorkflowState.Id).ToArray()
             };
 
             var json = JsonSerializer.Serialize(model);

src/modules/Elsa.Modules.MassTransit/Elsa.Modules.MassTransit.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net6.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\core\Elsa.ServiceBus.Abstractions\Elsa.ServiceBus.Abstractions.csproj" />
+      <ProjectReference Include="..\..\runtime\Elsa.Runtime\Elsa.Runtime.csproj" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <PackageReference Include="MassTransit" Version="8.0.1" />
+      <PackageReference Include="MassTransit.Extensions.DependencyInjection" Version="7.3.1" />
+    </ItemGroup>
+
+</Project>

src/modules/Elsa.Modules.MassTransit/Extensions/ServiceCollectionExtensions.cs

@@ -0,0 +1,13 @@
+using Elsa.Modules.MassTransit.Services;
+using Elsa.Runtime.Contracts;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Elsa.Modules.MassTransit.Extensions;
+
+public static class ServiceCollectionExtensions
+{
+    public static IServiceCollection AddMassTransitServices(this IServiceCollection services)
+    {
+        return services.AddSingleton<IWorkflowDispatcher, MassTransitWorkflowDispatcher>();
+    }
+}

src/modules/Elsa.Modules.MassTransit/Services/MassTransitServiceBus.cs

@@ -0,0 +1,12 @@
+using Elsa.ServiceBus.Abstractions.Contracts;
+using MassTransit;
+
+namespace Elsa.Modules.MassTransit.Services;
+
+public class MassTransitServiceBus : IServiceBus
+{
+    private readonly IBus _bus;
+    public MassTransitServiceBus(IBus bus) => _bus = bus;
+    public async Task SendAsync(object message, CancellationToken cancellationToken = default) => await _bus.Send(message, cancellationToken);
+    public async Task PublishAsync(object message, CancellationToken cancellationToken = default) => await _bus.Publish(message, cancellationToken);
+}

src/modules/Elsa.Modules.MassTransit/Services/MassTransitServiceBusProvider.cs

@@ -0,0 +1,16 @@
+using Elsa.ServiceBus.Abstractions.Contracts;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Elsa.Modules.MassTransit.Services;
+
+/// <summary>
+/// A MassTransit implementation for <see cref="IServiceBus"/>.
+/// </summary>
+public class MassTransitServiceBusProvider : IServiceBusProvider
+{
+    public void ConfigureServices(IServiceCollection services)
+    {
+        services
+            .AddSingleton<IServiceBus, MassTransitServiceBus>();
+    }
+}

src/modules/Elsa.Modules.MassTransit/Services/MassTransitWorkflowDispatcher.cs

@@ -0,0 +1,27 @@
+using Elsa.Runtime.Contracts;
+using Elsa.Runtime.Models;
+using MassTransit;
+
+namespace Elsa.Modules.MassTransit.Services;
+
+public class MassTransitWorkflowDispatcher : IWorkflowDispatcher
+{
+    private readonly IBus _bus;
+
+    public MassTransitWorkflowDispatcher(IBus bus)
+    {
+        _bus = bus;
+    }
+
+    public async Task<DispatchWorkflowDefinitionResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, CancellationToken cancellationToken = default)
+    {
+        await _bus.Send(request, cancellationToken);
+        return new();
+    }
+
+    public async Task<DispatchWorkflowInstanceResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, CancellationToken cancellationToken = default)
+    {
+        await _bus.Send(request, cancellationToken);
+        return new();
+    }
+}

src/modules/Elsa.Modules.Scheduling/Elsa.Modules.Scheduling.csproj

@@ -7,7 +7,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-      <ProjectReference Include="..\..\core\Elsa.Jobs\Elsa.Jobs.csproj" />
+      <ProjectReference Include="..\..\core\Elsa.Jobs.Abstractions\Elsa.Jobs.Abstractions.csproj" />
     </ItemGroup>
 
 </Project>

src/modules/Elsa.Modules.Scheduling/Jobs/ResumeWorkflowJob.cs

@@ -27,7 +27,7 @@ public class ResumeWorkflowJob : Job
     protected override async ValueTask ExecuteAsync(JobExecutionContext context)
     {
         var request = new DispatchWorkflowInstanceRequest(WorkflowInstanceId, Bookmark);
-        var workflowInvoker = context.GetRequiredService<IWorkflowInvoker>();
-        await workflowInvoker.DispatchAsync(request, context.CancellationToken);
+        var workflowDispatcher = context.GetRequiredService<IWorkflowDispatcher>();
+        await workflowDispatcher.DispatchAsync(request, context.CancellationToken);
     }
 }

src/modules/Elsa.Modules.Scheduling/Jobs/RunWorkflowJob.cs

@@ -25,7 +25,7 @@ public class RunWorkflowJob : Job
     protected override async ValueTask ExecuteAsync(JobExecutionContext context)
     {
         var request = new DispatchWorkflowDefinitionRequest(WorkflowId, VersionOptions.Published);
-        var workflowInvoker = context.GetRequiredService<IWorkflowInvoker>();
-        await workflowInvoker.DispatchAsync(request, context.CancellationToken);
+        var workflowDispatcher = context.GetRequiredService<IWorkflowDispatcher>();
+        await workflowDispatcher.DispatchAsync(request, context.CancellationToken);
     }
 }

src/runtime/Elsa.Runtime.ProtoActor/Actors/WorkflowInstanceActor.cs

@@ -1,60 +0,0 @@
-using System.Linq;
-using System.Threading.Tasks;
-using Elsa.Runtime.ProtoActor.Messages;
-using Proto;
-using Proto.DependencyInjection;
-
-namespace Elsa.Runtime.ProtoActor.Actors;
-
-/// <summary>
-/// Dispatches a workflow instance for execution. The workflow instance will be executed by <see cref="WorkflowOperatorActor"/>.
-/// </summary>
-public class WorkflowInstanceActor : IActor
-{
-    public Task ReceiveAsync(IContext context) => context.Message switch
-    {
-        ExecuteWorkflowInstance m => OnExecuteWorkflowInstanceAsync(context, m),
-        DispatchWorkflowInstance m => OnDispatchWorkflowInstanceAsync(context, m),
-        _ => Task.CompletedTask
-    };
-
-    private async Task OnExecuteWorkflowInstanceAsync(IContext context, ExecuteWorkflowInstance message)
-    {
-        var workflowInstanceId = message.Id;
-        var pid = GetWorkflowOperatorPid(context, workflowInstanceId);
-        var cancellationToken = context.CancellationToken;
-        var response = await context.RequestAsync<ExecuteWorkflowResponse>(pid, message, cancellationToken);
-            
-        context.Respond(response);
-    }
-        
-    private Task OnDispatchWorkflowInstanceAsync(IContext context, DispatchWorkflowInstance message)
-    {
-        var workflowInstanceId = message.Id;
-        var pid = GetWorkflowOperatorPid(context, workflowInstanceId);
-            
-        var executeWorkflowInstanceMessage = new ExecuteWorkflowInstance
-        {
-            Id = workflowInstanceId,
-            Bookmark = message.Bookmark,
-            Input = message.Input
-        };
-            
-        context.Send(pid, executeWorkflowInstanceMessage);
-        context.Respond(new Unit());
-        return Task.CompletedTask;
-    }
-
-    private PID GetWorkflowOperatorPid(IContext context, string workflowInstanceId)
-    {
-        var pid = context.System.ProcessRegistry.Find($"partition-activator/workflow-instance:{workflowInstanceId}").FirstOrDefault();
-            
-        if (pid != null) 
-            return pid;
-        
-        var props = context.System.DI().PropsFor<WorkflowOperatorActor>();
-        pid = context.SpawnNamed(props, workflowInstanceId);
-
-        return pid;
-    }
-}

src/runtime/Elsa.Runtime.ProtoActor/Elsa.Runtime.ProtoActor.csproj

@@ -18,6 +18,7 @@
     <ItemGroup Label="ProtoActor">
         <PackageReference Include="Proto.Actor" Version="0.29.0" />
         <PackageReference Include="Proto.Cluster" Version="0.29.0" />
+        <PackageReference Include="Proto.Cluster.CodeGen" Version="0.29.0" />
         <PackageReference Include="Proto.Cluster.Consul" Version="0.29.0" />
         <PackageReference Include="Proto.Cluster.Identity.Redis" Version="0.29.0" />
         <PackageReference Include="Proto.Cluster.TestProvider" Version="0.29.0" />
@@ -37,12 +38,16 @@
         <ProjectReference Include="..\Elsa.Runtime\Elsa.Runtime.csproj" />
     </ItemGroup>
 
-    <ItemGroup>
-        <Protobuf Include="messages.proto" />
-    </ItemGroup>
-
-    <ItemGroup>
-        <Folder Include="Contracts" />
+    <ItemGroup Label="Protos">
+        <Protobuf Include="Protos\Messages.proto">
+            <GrpcServices>Both</GrpcServices>
+            <Access>Public</Access>
+            <ProtoCompile>True</ProtoCompile>
+            <CompileOutputs>True</CompileOutputs>
+            <OutputDir>obj\Debug\net6.0\</OutputDir>
+            <Generator>MSBuild:Compile</Generator>
+        </Protobuf>
+        <ProtoGrain Include="Protos\Grains.proto" AdditionalImportDirs="Protos" />
     </ItemGroup>
 
 </Project>

src/runtime/Elsa.Runtime.ProtoActor/Extensions/ProtoInputExtensions.cs

@@ -1,7 +1,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text.Json;
-using Elsa.Runtime.ProtoActor.Messages;
+using Elsa.Runtime.Protos;
 
 namespace Elsa.Runtime.ProtoActor.Extensions;
 

src/runtime/Elsa.Runtime.ProtoActor/Extensions/ServiceCollectionExtensions.cs

@@ -1,8 +1,12 @@
 using System;
+using Elsa.Helpers;
+using Elsa.Persistence.Models;
 using Elsa.Runtime.Contracts;
-using Elsa.Runtime.ProtoActor.Actors;
+using Elsa.Runtime.Extensions;
+using Elsa.Runtime.ProtoActor.Grains;
 using Elsa.Runtime.ProtoActor.HostedServices;
 using Elsa.Runtime.ProtoActor.Services;
+using Elsa.Runtime.Protos;
 using Microsoft.Extensions.DependencyInjection;
 using Proto;
 using Proto.Cluster;
@@ -20,12 +24,13 @@ public static class ServiceCollectionExtensions
     {
         var systemConfig = GetSystemConfig();
 
+        // Actor System.
         services.AddSingleton(sp =>
         {
             var system = new ActorSystem(systemConfig).WithServiceProvider(sp);
             var remoteConfig = GetRemoteConfig();
             var clusterConfig = GetClusterConfig(system, "my-cluster");
-            
+
             system
                 .WithRemote(remoteConfig)
                 .WithCluster(clusterConfig);
@@ -33,37 +38,43 @@ public static class ServiceCollectionExtensions
             return system;
         });
 
+        // Cluster.
         services.AddSingleton(sp => sp.GetRequiredService<ActorSystem>().Cluster());
 
-        return services
-            .AddHostedService<WorkflowServerHost>()
-            .AddSingleton<IWorkflowInvoker, ProtoActorWorkflowInvoker>()
-            .AddTransient<WorkflowDefinitionActor>()
-            .AddTransient<WorkflowInstanceActor>()
-            .AddTransient<WorkflowOperatorActor>();
-    }
-        
-    private static ActorSystemConfig GetSystemConfig() =>
+        // Actors.
+        services
+            .AddSingleton(sp => new WorkflowDefinitionGrainActor((context, _) => ActivatorUtilities.CreateInstance<WorkflowDefinitionGrain>(sp, context)))
+            .AddSingleton(sp => new WorkflowInstanceGrainActor((context, _) => ActivatorUtilities.CreateInstance<WorkflowInstanceGrain>(sp, context)));
 
+        // Client factory.
+        services.AddSingleton<GrainClientFactory>();
+
+        // Configure runtime with ProtoActor workflow invoker.
+        services.ConfigureWorkflowRuntime(options => options.WorkflowInvokerFactory = sp => ActivatorUtilities.CreateInstance<ProtoActorWorkflowInvoker>(sp));
+
+        return services
+            .AddHostedService<WorkflowServerHost>();
+    }
+
+    private static ActorSystemConfig GetSystemConfig() =>
         ActorSystemConfig
             .Setup()
             .WithDeadLetterThrottleCount(3)
             .WithDeadLetterThrottleInterval(TimeSpan.FromSeconds(10000))
             .WithDeveloperSupervisionLogging(true)
             .WithDeadLetterRequestLogging(true);
-        
+
     private static GrpcCoreRemoteConfig GetRemoteConfig() => GrpcCoreRemoteConfig
         .BindToLocalhost()
-        .WithProtoMessages(Messages.MessagesReflection.Descriptor)
-    ;
-        
+        .WithProtoMessages(Protos.MessagesReflection.Descriptor);
+
     private static ClusterConfig GetClusterConfig(ActorSystem system, string clusterName)
     {
         //var clusterProvider = new ConsulProvider(new ConsulProviderConfig{});
         var clusterProvider = new TestProvider(new TestProviderOptions(), new InMemAgent());
-            
-        var workflowDefinitionProps = system.DI().PropsFor<WorkflowDefinitionActor>();
-        var workflowInstanceProps = system.DI().PropsFor<WorkflowInstanceActor>();
+
+        var workflowDefinitionProps = system.DI().PropsFor<WorkflowDefinitionGrainActor>();
+        var workflowInstanceProps = system.DI().PropsFor<WorkflowInstanceGrainActor>();
 
         var clusterConfig =
                 ClusterConfig
@@ -73,12 +84,12 @@ public static class ServiceCollectionExtensions
                     .WithActorRequestTimeout(TimeSpan.FromHours(1))
                     .WithActorActivationTimeout(TimeSpan.FromHours(1))
                     .WithActorSpawnTimeout(TimeSpan.FromHours(1))
-                    .WithClusterKind(GrainKinds.WorkflowDefinition, workflowDefinitionProps)
-                    .WithClusterKind(GrainKinds.WorkflowInstance, workflowInstanceProps)
+                    .WithClusterKind(WorkflowDefinitionGrainActor.Kind, workflowDefinitionProps)
+                    .WithClusterKind(WorkflowInstanceGrainActor.Kind, workflowInstanceProps)
             ;
         return clusterConfig;
     }
-        
+
     // private static IIdentityStorage GetIdentityLookup(string clusterName) =>
     //     new RedisIdentityStorage(clusterName, ConnectionMultiplexer
     //         .Connect("localhost:6379" /* use proper config */)

src/runtime/Elsa.Runtime.ProtoActor/GrainKinds.cs

@@ -1,7 +0,0 @@
-namespace Elsa.Runtime.ProtoActor;
-
-public static class GrainKinds
-{
-    public const string WorkflowDefinition = "WorkflowDefinition";
-    public const string WorkflowInstance = "WorkflowInstance";
-}

src/runtime/Elsa.Runtime.ProtoActor/Grains/WorkflowDefinitionGrain.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Threading;
 using System.Threading.Tasks;
 using Elsa.Contracts;
@@ -6,69 +7,64 @@ using Elsa.Persistence.Commands;
 using Elsa.Persistence.Entities;
 using Elsa.Persistence.Models;
 using Elsa.Runtime.Contracts;
-using Elsa.Runtime.ProtoActor.Messages;
+using Elsa.Runtime.ProtoActor.Services;
+using Elsa.Runtime.Protos;
 using Elsa.State;
 using Proto;
-using Proto.Cluster;
-using Unit = Elsa.Runtime.ProtoActor.Messages.Unit;
 
-namespace Elsa.Runtime.ProtoActor.Actors;
+namespace Elsa.Runtime.ProtoActor.Grains;
 
 /// <summary>
-/// Instantiates and dispatches a workflow instance for execution. The workflow instance will be executed by <see cref="WorkflowOperatorActor"/>.
+/// Instantiates and executes a workflow instance for execution.
 /// </summary>
-public class WorkflowDefinitionActor : IActor
+public class WorkflowDefinitionGrain : WorkflowDefinitionGrainBase
 {
     private readonly IWorkflowRegistry _workflowRegistry;
     private readonly ICommandSender _commandSender;
     private readonly IIdentityGenerator _identityGenerator;
     private readonly ISystemClock _systemClock;
+    private readonly GrainClientFactory _grainClientFactory;
 
-    public WorkflowDefinitionActor(IWorkflowRegistry workflowRegistry, ICommandSender commandSender, IIdentityGenerator identityGenerator, ISystemClock systemClock)
+    public WorkflowDefinitionGrain(
+        IWorkflowRegistry workflowRegistry, 
+        ICommandSender commandSender, 
+        IIdentityGenerator identityGenerator, 
+        ISystemClock systemClock,
+        GrainClientFactory grainClientFactory,
+        IContext context) : base(context)
     {
         _workflowRegistry = workflowRegistry;
         _commandSender = commandSender;
         _identityGenerator = identityGenerator;
         _systemClock = systemClock;
+        _grainClientFactory = grainClientFactory;
     }
-
-    public Task ReceiveAsync(IContext context) => context.Message switch
+    
+    public override async Task<ExecuteWorkflowDefinitionResponse> Execute(ExecuteWorkflowDefinitionRequest request)
     {
-        ExecuteWorkflowDefinition i => OnExecuteWorkflowDefinitionAsync(context, i),
-        DispatchWorkflowDefinition i => OnDispatchWorkflowDefinitionAsync(context, i),
-        _ => Task.CompletedTask
-    };
-
-    private async Task OnExecuteWorkflowDefinitionAsync(IContext context, ExecuteWorkflowDefinition message)
-    {
-        var workflowDefinitionId = message.Id;
-        var cancellationToken = context.CancellationToken;
+        var workflowDefinitionId = request.Id;
+        var cancellationToken = Context.CancellationToken;
         var workflowInstance = await CreateWorkflowInstanceAsync(workflowDefinitionId, cancellationToken);
 
-        var executeWorkflowInstanceMessage = new ExecuteWorkflowInstance
+        var executeWorkflowInstanceMessage = new ExecuteWorkflowInstanceRequest
         {
             Id = workflowInstance.Id,
-            Input = message.Input
+            Input = request.Input
         };
 
-        var response = await context.ClusterRequestAsync<ExecuteWorkflowResponse>(workflowInstance.Id, GrainKinds.WorkflowInstance, executeWorkflowInstanceMessage, cancellationToken);
-        context.Respond(response);
-    }
+        var workflowInstanceGrainClient = Context.GetWorkflowInstanceGrain(workflowInstance.Id);
+        var workflowInstanceResponse = await workflowInstanceGrainClient.Execute(executeWorkflowInstanceMessage, cancellationToken);
+        
+        if (workflowInstanceResponse == null)
+            throw new TimeoutException("Did not receive a response from the WorkflowInstance actor within the configured amount of time.");
 
-    private async Task OnDispatchWorkflowDefinitionAsync(IContext context, DispatchWorkflowDefinition message)
-    {
-        var workflowDefinitionId = message.Id;
-        var cancellationToken = context.CancellationToken;
-        var workflowInstance = await CreateWorkflowInstanceAsync(workflowDefinitionId, cancellationToken);
-
-        var dispatchWorkflowInstanceMessage = new DispatchWorkflowInstance
+        var response = new ExecuteWorkflowDefinitionResponse
         {
-            Id = workflowInstance.Id,
-            Input = message.Input
+            WorkflowState = workflowInstanceResponse.WorkflowState,
         };
 
-        await context.ClusterRequestAsync<Unit>(workflowInstance.Id, GrainKinds.WorkflowInstance, dispatchWorkflowInstanceMessage, cancellationToken);
-        context.Respond(new Unit());
+        response.Bookmarks.AddRange(workflowInstanceResponse.Bookmarks);
+        return response;
     }
 
     private async Task<WorkflowInstance> CreateWorkflowInstanceAsync(string workflowDefinitionId, CancellationToken cancellationToken)

src/runtime/Elsa.Runtime.ProtoActor/Grains/WorkflowInstanceGrain.cs

@@ -11,42 +11,45 @@ using Elsa.Persistence.Models;
 using Elsa.Persistence.Requests;
 using Elsa.Runtime.Contracts;
 using Elsa.Runtime.ProtoActor.Extensions;
-using Elsa.Runtime.ProtoActor.Messages;
+using Elsa.Runtime.ProtoActor.Services;
+using Elsa.Runtime.Protos;
 using Elsa.Serialization;
 using Elsa.State;
 using Proto;
-using Bookmark = Elsa.Runtime.ProtoActor.Messages.Bookmark;
+using Bookmark = Elsa.Runtime.Protos.Bookmark;
 
-namespace Elsa.Runtime.ProtoActor.Actors;
+namespace Elsa.Runtime.ProtoActor.Grains;
 
 /// <summary>
 /// Executes a workflow instance.
 /// </summary>
-public class WorkflowOperatorActor : IActor
+public class WorkflowInstanceGrain : WorkflowInstanceGrainBase
 {
     private readonly IRequestSender _requestSender;
     private readonly IWorkflowRegistry _workflowRegistry;
+    private readonly GrainClientFactory _grainClientFactory;
     private readonly IWorkflowRunner _workflowRunner;
     private readonly WorkflowSerializerOptionsProvider _workflowSerializerOptionsProvider;
 
-    public WorkflowOperatorActor(IRequestSender requestSender, IWorkflowRegistry workflowRegistry, IWorkflowRunner workflowRunner, WorkflowSerializerOptionsProvider workflowSerializerOptionsProvider)
+    public WorkflowInstanceGrain(
+        IRequestSender requestSender, 
+        IWorkflowRegistry workflowRegistry, 
+        GrainClientFactory grainClientFactory,
+        IWorkflowRunner workflowRunner,
+        WorkflowSerializerOptionsProvider workflowSerializerOptionsProvider, 
+        IContext context) : base(context)
     {
         _requestSender = requestSender;
         _workflowRegistry = workflowRegistry;
+        _grainClientFactory = grainClientFactory;
         _workflowRunner = workflowRunner;
         _workflowSerializerOptionsProvider = workflowSerializerOptionsProvider;
     }
 
-    public Task ReceiveAsync(IContext context) => context.Message switch
+    public override async Task<ExecuteWorkflowInstanceResponse> Execute(ExecuteWorkflowInstanceRequest request)
     {
-        ExecuteWorkflowInstance m => OnExecuteWorkflowInstance(context, m),
-        _ => Task.CompletedTask
-    };
-
-    private async Task OnExecuteWorkflowInstance(IContext context, ExecuteWorkflowInstance message)
-    {
-        var workflowInstanceId = message.Id;
-        var cancellationToken = context.CancellationToken;
+        var workflowInstanceId = request.Id;
+        var cancellationToken = Context.CancellationToken;
         var workflowInstance = await _requestSender.RequestAsync(new FindWorkflowInstance(workflowInstanceId), cancellationToken);
 
         if (workflowInstance == null)
@@ -59,15 +62,30 @@ public class WorkflowOperatorActor : IActor
             throw new Exception($"No workflow definition found with ID {workflowDefinitionId}");
 
         var workflowState = workflowInstance.WorkflowState;
-        var bookmarkMessage = message.Bookmark;
-        var input = message.Input?.Deserialize();
-        var executionResult = await ExecuteAsync(workflow, workflowState, bookmarkMessage, input, cancellationToken);
+        var bookmarkMessage = request.Bookmark;
+        var input = request.Input?.Deserialize();
+        var executionResult = await ExecuteAsync(workflow, workflowState, bookmarkMessage, input!, cancellationToken);
         var response = MapResult(executionResult);
 
-        context.Respond(response);
+        return response;
     }
 
-    private ExecuteWorkflowResponse MapResult(ExecuteWorkflowResult result)
+    // public override async Task Dispatch(DispatchWorkflowInstanceRequest request)
+    // {
+    //     var workflowInstanceId = request.Id;
+    //     //var pid = GetWorkflowOperatorPid(Context, workflowInstanceId);
+    //
+    //     var executeWorkflowInstanceMessage = new ExecuteWorkflowInstanceRequest
+    //     {
+    //         Id = workflowInstanceId,
+    //         Bookmark = request.Bookmark,
+    //         Input = request.Input
+    //     };
+
+        //Context.Send(pid, executeWorkflowInstanceMessage);
+    //}
+
+    private ExecuteWorkflowInstanceResponse MapResult(InvokeWorkflowResult result)
     {
         var bookmarks = result.Bookmarks.Select(x => new Bookmark
         {
@@ -79,10 +97,10 @@ public class WorkflowOperatorActor : IActor
             ActivityInstanceId = x.ActivityInstanceId,
             CallbackMethodName = x.CallbackMethodName
         });
-        
+
         var options = _workflowSerializerOptionsProvider.CreatePersistenceOptions();
 
-        var response = new ExecuteWorkflowResponse
+        var response = new ExecuteWorkflowInstanceResponse
         {
             WorkflowState = new Json
             {
@@ -95,7 +113,7 @@ public class WorkflowOperatorActor : IActor
         return response;
     }
 
-    private async Task<ExecuteWorkflowResult> ExecuteAsync(Workflow workflow, WorkflowState workflowState, Bookmark? bookmarkMessage, IDictionary<string, object>? input, CancellationToken cancellationToken)
+    private async Task<InvokeWorkflowResult> ExecuteAsync(Workflow workflow, WorkflowState workflowState, Bookmark? bookmarkMessage, IDictionary<string, object>? input, CancellationToken cancellationToken)
     {
         if (bookmarkMessage == null)
             return await _workflowRunner.RunAsync(workflow, workflowState, input, cancellationToken);

src/runtime/Elsa.Runtime.ProtoActor/HostedServices/WorkflowServerHost.cs

@@ -6,17 +6,13 @@ using Proto.Cluster;
 
 namespace Elsa.Runtime.ProtoActor.HostedServices;
 
-public class WorkflowServerHost : BackgroundService
+/// <summary>
+/// Starts the current member in the cluster.
+/// </summary>
+public class WorkflowServerHost : IHostedService
 {
     private readonly ActorSystem _actorSystem;
-
-    public WorkflowServerHost(ActorSystem actorSystem)
-    {
-        _actorSystem = actorSystem;
-    }
-        
-    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
-    {
-        await _actorSystem.Cluster().StartMemberAsync();
-    }
+    public WorkflowServerHost(ActorSystem actorSystem) => _actorSystem = actorSystem;
+    public async Task StartAsync(CancellationToken cancellationToken) => await _actorSystem.Cluster().StartMemberAsync();
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 }

src/runtime/Elsa.Runtime.ProtoActor/Protos/Grains.proto

@@ -0,0 +1,14 @@
+syntax = "proto3";
+
+option csharp_namespace = "Elsa.Runtime.Protos";
+
+import "google/protobuf/empty.proto";
+import "Messages.proto";
+
+service WorkflowDefinitionGrain {
+  rpc Execute (ExecuteWorkflowDefinitionRequest) returns (ExecuteWorkflowDefinitionResponse);
+}
+
+service WorkflowInstanceGrain {
+  rpc Execute (ExecuteWorkflowInstanceRequest) returns (ExecuteWorkflowInstanceResponse);
+}

src/runtime/Elsa.Runtime.ProtoActor/Protos/Messages.proto

@@ -1,41 +1,31 @@
 syntax = "proto3";
 import "google/protobuf/wrappers.proto";
 package Elsa.Runtime.ProtoActor.Messages;
-option csharp_namespace = "Elsa.Runtime.ProtoActor.Messages";
+option csharp_namespace = "Elsa.Runtime.Protos";
 
 // Empty response type.
 message Unit {}
 
-message ExecuteWorkflowDefinition {
+message ExecuteWorkflowDefinitionRequest {
   string id = 1;
   string versionOptions = 2;
   optional Input input = 3;
 }
 
-message DispatchWorkflowDefinition {
-  string id = 1;
-  string versionOptions = 2;
-  optional Input input = 3;
-}
-
-message ExecuteWorkflowInstance {
-  string id = 1;
-  optional Bookmark bookmark = 2;
-  optional Input input = 3;
-}
-
-message DispatchWorkflowInstance {
-  string id = 1;
-  optional Bookmark bookmark = 2;
-  optional Input input = 3;
-}
-
-message ExecuteWorkflowResponse {
+message ExecuteWorkflowDefinitionResponse {
   Json workflowState = 1;
   repeated Bookmark bookmarks = 2;
 }
 
-message DispatchWorkflowResponse {
+message ExecuteWorkflowInstanceRequest {
+  string id = 1;
+  optional Bookmark bookmark = 2;
+  optional Input input = 3;
+}
+
+message ExecuteWorkflowInstanceResponse {
+  Json workflowState = 1;
+  repeated Bookmark bookmarks = 2;
 }
 
 message HandleStimulusRequest {

src/runtime/Elsa.Runtime.ProtoActor/Services/GrainClientFactory.cs

@@ -0,0 +1,18 @@
+using Elsa.Persistence.Models;
+using Elsa.Runtime.Protos;
+using Proto.Cluster;
+
+namespace Elsa.Runtime.ProtoActor.Services;
+
+public class GrainClientFactory
+{
+    private readonly Cluster _cluster;
+
+    public GrainClientFactory(Cluster cluster)
+    {
+        _cluster = cluster;
+    }
+
+    public WorkflowDefinitionGrainClient CreateWorkflowDefinitionGrainClient(string workflowDefinitionId, VersionOptions versionOptions) => _cluster.GetWorkflowDefinitionGrain($"workflow-definition:{workflowDefinitionId}:{versionOptions.ToString()}");
+    public WorkflowInstanceGrainClient CreateWorkflowInstanceGrainClient(string workflowInstanceId) => _cluster.GetWorkflowInstanceGrain($"workflow-instance:{workflowInstanceId}");
+}

src/runtime/Elsa.Runtime.ProtoActor/Services/ProtoActorWorkflowInvoker.cs

@@ -1,110 +1,85 @@
+using System;
 using System.Linq;
 using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 using Elsa.Models;
-using Elsa.Persistence.Models;
 using Elsa.Runtime.Contracts;
 using Elsa.Runtime.Models;
 using Elsa.Runtime.ProtoActor.Extensions;
-using Elsa.Runtime.ProtoActor.Messages;
+using Elsa.Runtime.Protos;
 using Elsa.State;
+using Proto;
 using Proto.Cluster;
+using Bookmark = Elsa.Models.Bookmark;
+using ProtoBookmark = Elsa.Runtime.Protos.Bookmark;
 
 namespace Elsa.Runtime.ProtoActor.Services;
 
-using Bookmark = Elsa.Models.Bookmark;
-using BookmarkMessage = Messages.Bookmark;
-
 public class ProtoActorWorkflowInvoker : IWorkflowInvoker
 {
     private readonly Cluster _cluster;
+    private readonly GrainClientFactory _grainClientFactory;
 
-    public ProtoActorWorkflowInvoker(Cluster cluster)
+    public ProtoActorWorkflowInvoker(Cluster cluster, GrainClientFactory grainClientFactory)
     {
         _cluster = cluster;
+        _grainClientFactory = grainClientFactory;
     }
 
-    public async Task<ExecuteWorkflowResult> ExecuteAsync(ExecuteWorkflowDefinitionRequest request, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> InvokeAsync(InvokeWorkflowDefinitionRequest request, CancellationToken cancellationToken = default)
     {
         var (definitionId, versionOptions, input) = request;
-        var name = GetActorName(definitionId, versionOptions);
-
-        var message = new ExecuteWorkflowDefinition
+        
+        var message = new ExecuteWorkflowDefinitionRequest
         {
             Id = definitionId,
             VersionOptions = versionOptions.ToString(),
             Input = input!?.Serialize()
         };
 
-        var response = await _cluster.RequestAsync<ExecuteWorkflowResponse>(name, GrainKinds.WorkflowDefinition, message, cancellationToken);
+        var client = _grainClientFactory.CreateWorkflowDefinitionGrainClient(definitionId, versionOptions);
+        var response = await client.Execute(message, CancellationTokens.FromSeconds(100));
+
+        if (response == null)
+            throw new TimeoutException("Did not receive a response from the WorkflowDefinition actor within the configured amount of time.");
+        
         var workflowState = JsonSerializer.Deserialize<WorkflowState>(response.WorkflowState.Text)!;
         var bookmarks = response.Bookmarks.Select(MapBookmark).ToList();
 
-        return new ExecuteWorkflowResult(workflowState, bookmarks);
+        return new InvokeWorkflowResult(workflowState, bookmarks);
     }
 
-    public async Task<ExecuteWorkflowResult> ExecuteAsync(ExecuteWorkflowInstanceRequest request, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> InvokeAsync(InvokeWorkflowInstanceRequest request, CancellationToken cancellationToken = default)
     {
         var (instanceId, bookmark, input) = request;
-        var name = GetActorName(instanceId);
         var bookmarkMessage = MapBookmark(bookmark);
 
-        var message = new ExecuteWorkflowInstance
-        {
-            Id = instanceId,
-            Bookmark = bookmarkMessage,
-            Input = input?.Serialize()
-        };
-
-        var response = await _cluster.RequestAsync<ExecuteWorkflowResponse>(name, GrainKinds.WorkflowInstance, message, cancellationToken);
-        var workflowState = JsonSerializer.Deserialize<WorkflowState>(response.WorkflowState.Text)!;
-        var bookmarks = response.Bookmarks.Select(MapBookmark).ToList();
-
-        return new ExecuteWorkflowResult(workflowState, bookmarks);
-    }
-
-    public async Task<DispatchWorkflowResult> DispatchAsync(DispatchWorkflowDefinitionRequest request, CancellationToken cancellationToken = default)
-    {
-        var (definitionId, versionOptions, input) = request;
-        var name = GetActorName(definitionId, versionOptions);
-
-        var message = new DispatchWorkflowDefinition
-        {
-            Id = definitionId,
-            VersionOptions = versionOptions.ToString(),
-            Input = input!?.Serialize()
-        };
-
-        await _cluster.RequestAsync<Unit>(name, GrainKinds.WorkflowDefinition, message, cancellationToken);
-
-        return new DispatchWorkflowResult();
-    }
-
-    public async Task<DispatchWorkflowResult> DispatchAsync(DispatchWorkflowInstanceRequest request, CancellationToken cancellationToken = default)
-    {
-        var (instanceId, bookmark, input) = request;
-        var name = GetActorName(instanceId);
-        var bookmarkMessage = MapBookmark(bookmark);
-
-        var message = new DispatchWorkflowInstance
+        var message = new ExecuteWorkflowInstanceRequest
         {
             Id = instanceId,
             Bookmark = bookmarkMessage,
             Input = input!?.Serialize()
         };
 
-        await _cluster.RequestAsync<Unit>(name, GrainKinds.WorkflowInstance, message, cancellationToken);
+        var client = _grainClientFactory.CreateWorkflowInstanceGrainClient(instanceId);
+        var response = await client.Execute(message, cancellationToken);
+        
+        if (response == null)
+            throw new TimeoutException("Did not receive a response from the WorkflowInstance actor within the configured amount of time.");
+        
+        var workflowState = JsonSerializer.Deserialize<WorkflowState>(response.WorkflowState.Text)!;
+        var bookmarks = response.Bookmarks.Select(MapBookmark).ToList();
 
-        return new DispatchWorkflowResult();
+        return new InvokeWorkflowResult(workflowState, bookmarks);
     }
-
-    private BookmarkMessage? MapBookmark(Bookmark? bookmark)
+    
+    private ProtoBookmark? MapBookmark(Bookmark? bookmark)
     {
         if (bookmark == null)
             return null;
 
-        return new BookmarkMessage
+        return new ProtoBookmark
         {
             Id = bookmark.Id,
             Name = bookmark.Name,
@@ -116,19 +91,16 @@ public class ProtoActorWorkflowInvoker : IWorkflowInvoker
         };
     }
 
-    private Bookmark MapBookmark(BookmarkMessage bookmarkMessage)
+    private Bookmark MapBookmark(ProtoBookmark protoBookmark)
     {
         return new Bookmark(
-            bookmarkMessage.Id,
-            bookmarkMessage.Name,
-            bookmarkMessage.Hash,
-            bookmarkMessage.Payload,
-            bookmarkMessage.ActivityId,
-            bookmarkMessage.ActivityInstanceId,
-            bookmarkMessage.CallbackMethodName
+            protoBookmark.Id,
+            protoBookmark.Name,
+            protoBookmark.Hash,
+            protoBookmark.Payload,
+            protoBookmark.ActivityId,
+            protoBookmark.ActivityInstanceId,
+            protoBookmark.CallbackMethodName
         );
     }
-
-    private static string GetActorName(string definitionId, VersionOptions versionOptions) => $"workflow-definition:{definitionId}:{versionOptions.ToString()}";
-    private static string GetActorName(string instanceId) => $"workflow-instance:{instanceId}";
 }

src/runtime/Elsa.Runtime/Contracts/ExecuteWorkflowInstructionResult.cs

@@ -2,4 +2,4 @@ using Elsa.Models;
 
 namespace Elsa.Runtime.Contracts;
 
-public record ExecuteWorkflowInstructionResult(Workflow Workflow, ExecuteWorkflowResult ExecuteWorkflowResult);
+public record ExecuteWorkflowInstructionResult(Workflow Workflow, InvokeWorkflowResult InvokeWorkflowResult);

src/runtime/Elsa.Runtime/Contracts/IWorkflowDispatcher.cs

@@ -0,0 +1,13 @@
+using Elsa.Models;
+using Elsa.Runtime.Models;
+
+namespace Elsa.Runtime.Contracts;
+
+/// <summary>
+/// Posts a message to a queue to invoke a specified workflow.
+/// </summary>
+public interface IWorkflowDispatcher
+{
+    Task<DispatchWorkflowDefinitionResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowInstanceResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, CancellationToken cancellationToken = default);
+}

src/runtime/Elsa.Runtime/Contracts/IWorkflowInvoker.cs

@@ -3,10 +3,18 @@ using Elsa.Runtime.Models;
 
 namespace Elsa.Runtime.Contracts;
 
+/// <summary>
+/// Invokes a workflow using a configured runtime (e.g. ProtoActor).
+/// </summary>
 public interface IWorkflowInvoker
 {
-    Task<ExecuteWorkflowResult> ExecuteAsync(ExecuteWorkflowDefinitionRequest request, CancellationToken cancellationToken = default);
-    Task<ExecuteWorkflowResult> ExecuteAsync(ExecuteWorkflowInstanceRequest request, CancellationToken cancellationToken = default);
-    Task<DispatchWorkflowResult> DispatchAsync(DispatchWorkflowDefinitionRequest request, CancellationToken cancellationToken = default);
-    Task<DispatchWorkflowResult> DispatchAsync(DispatchWorkflowInstanceRequest request, CancellationToken cancellationToken = default);
+    /// <summary>
+    /// Creates a workflow instance of the specified workflow definition and then invokes the workflow instance.
+    /// </summary>
+    Task<InvokeWorkflowResult> InvokeAsync(InvokeWorkflowDefinitionRequest request, CancellationToken cancellationToken = default);
+    
+    /// <summary>
+    /// Invokes the specified workflow instance.
+    /// </summary>
+    Task<InvokeWorkflowResult> InvokeAsync(InvokeWorkflowInstanceRequest request, CancellationToken cancellationToken = default);
 }

src/runtime/Elsa.Runtime/Contracts/IWorkflowService.cs

@@ -1,5 +1,6 @@
 using Elsa.Models;
 using Elsa.Persistence.Models;
+using Elsa.Runtime.Models;
 
 namespace Elsa.Runtime.Contracts;
 
@@ -8,10 +9,10 @@ namespace Elsa.Runtime.Contracts;
 /// </summary>
 public interface IWorkflowService
 {
-    Task<ExecuteWorkflowResult> ExecuteWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
-    Task<ExecuteWorkflowResult> ExecuteWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
-    Task<DispatchWorkflowResult> DispatchWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
-    Task<DispatchWorkflowResult> DispatchWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<InvokeWorkflowResult> ExecuteWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<InvokeWorkflowResult> ExecuteWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowDefinitionResponse> DispatchWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowInstanceResponse> DispatchWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default);
     Task<IEnumerable<ExecuteWorkflowInstructionResult>> ExecuteStimulusAsync(IStimulus stimulus, CancellationToken cancellationToken);
     Task<IEnumerable<DispatchWorkflowInstructionResult>> DispatchStimulusAsync(IStimulus stimulus, CancellationToken cancellationToken);
         

src/runtime/Elsa.Runtime/Extensions/ServiceCollectionExtensions.cs

@@ -1,13 +1,16 @@
+using System.Threading.Channels;
 using Elsa.Expressions;
 using Elsa.Mediator.Extensions;
 using Elsa.Runtime.Contracts;
 using Elsa.Runtime.HostedServices;
 using Elsa.Runtime.Interpreters;
+using Elsa.Runtime.Models;
 using Elsa.Runtime.Options;
 using Elsa.Runtime.Services;
 using Elsa.Runtime.Stimuli.Handlers;
 using Elsa.Runtime.WorkflowProviders;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
 
 namespace Elsa.Runtime.Extensions;
 
@@ -24,6 +27,8 @@ public static class ServiceCollectionExtensions
                 .AddSingleton<IWorkflowInstructionExecutor, WorkflowInstructionExecutor>()
                 .AddSingleton<ITriggerIndexer, TriggerIndexer>()
                 .AddSingleton<IBookmarkManager, BookmarkManager>()
+                .AddSingleton(sp => sp.GetRequiredService<IOptions<WorkflowRuntimeOptions>>().Value.WorkflowInvokerFactory(sp))
+                .AddSingleton(sp => sp.GetRequiredService<IOptions<WorkflowRuntimeOptions>>().Value.WorkflowDispatcherFactory(sp))
 
                 // Stimulus handlers.
                 .AddStimulusHandler<TriggerWorkflowsStimulusHandler>()
@@ -42,13 +47,29 @@ public static class ServiceCollectionExtensions
 
                 // Domain event handlers.
                 .AddNotificationHandlersFrom(typeof(ServiceCollectionExtensions))
-            
+
                 // Hosted Services.
                 .AddHostedService<RegisterDescriptors>()
-                .AddHostedService<RegisterExpressionSyntaxDescriptors>();
+                .AddHostedService<RegisterExpressionSyntaxDescriptors>()
+                .AddHostedService<DispatchedWorkflowDefinitionWorker>()
+                .AddHostedService<DispatchedWorkflowInstanceWorker>()
+
+                // Channels for dispatching workflows in-memory.
+                .CreateChannel<DispatchWorkflowDefinitionRequest>()
+                .CreateChannel<DispatchWorkflowInstanceRequest>()
             ;
     }
 
+    private static IServiceCollection CreateChannel<T>(this IServiceCollection services) =>
+        services
+            .AddSingleton(CreateChannel<T>())
+            .AddSingleton(CreateChannelReader<T>)
+            .AddSingleton(CreateChannelWriter<T>);
+
+    private static Channel<T> CreateChannel<T>() => Channel.CreateUnbounded<T>(new UnboundedChannelOptions());
+    private static ChannelReader<T> CreateChannelReader<T>(IServiceProvider serviceProvider) => serviceProvider.GetRequiredService<Channel<T>>().Reader;
+    private static ChannelWriter<T> CreateChannelWriter<T>(IServiceProvider serviceProvider) => serviceProvider.GetRequiredService<Channel<T>>().Writer;
+
     private static IServiceCollection AddDefaultExpressionHandlers(this IServiceCollection services) =>
         services
             .AddExpressionHandler<LiteralExpressionHandler, LiteralExpression>()

src/runtime/Elsa.Runtime/HostedServices/DispatchedWorkflowDefinitionWorker.cs

@@ -0,0 +1,42 @@
+using System.Threading.Channels;
+using Elsa.Runtime.Contracts;
+using Elsa.Runtime.Models;
+using Elsa.Runtime.Services;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Elsa.Runtime.HostedServices;
+
+public class DispatchedWorkflowDefinitionWorker : BackgroundService
+{
+    private readonly ChannelReader<DispatchWorkflowDefinitionRequest> _channelReader;
+    private readonly IWorkflowInvoker _workflowInvoker;
+    private readonly ILogger _logger;
+
+    public DispatchedWorkflowDefinitionWorker(
+        ChannelReader<DispatchWorkflowDefinitionRequest> channelReader,
+        IWorkflowInvoker workflowInvoker,
+        ILogger<DispatchedWorkflowDefinitionWorker> logger)
+    {
+        _channelReader = channelReader;
+        _workflowInvoker = workflowInvoker;
+        _logger = logger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken cancellationToken)
+    {
+        await foreach (var (definitionId, versionOptions, input) in _channelReader.ReadAllAsync(cancellationToken))
+        {
+            var request = new InvokeWorkflowDefinitionRequest(definitionId, versionOptions, input);
+
+            try
+            {
+                await _workflowInvoker.InvokeAsync(request, cancellationToken);
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "An unhandled exception occured while processing the queue");
+            }
+        }
+    }
+}

src/runtime/Elsa.Runtime/HostedServices/DispatchedWorkflowInstanceWorker.cs

@@ -0,0 +1,41 @@
+using System.Threading.Channels;
+using Elsa.Runtime.Contracts;
+using Elsa.Runtime.Models;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Elsa.Runtime.HostedServices;
+
+public class DispatchedWorkflowInstanceWorker : BackgroundService
+{
+    private readonly ChannelReader<DispatchWorkflowInstanceRequest> _channelReader;
+    private readonly IWorkflowInvoker _workflowInvoker;
+    private readonly ILogger _logger;
+
+    public DispatchedWorkflowInstanceWorker(
+        ChannelReader<DispatchWorkflowInstanceRequest> channelReader,
+        IWorkflowInvoker workflowInvoker,
+        ILogger<DispatchedWorkflowInstanceWorker> logger)
+    {
+        _channelReader = channelReader;
+        _workflowInvoker = workflowInvoker;
+        _logger = logger;
+    }
+
+    protected override async Task ExecuteAsync(CancellationToken cancellationToken)
+    {
+        await foreach (var (instanceId, bookmark, input) in _channelReader.ReadAllAsync(cancellationToken))
+        {
+            var request = new InvokeWorkflowInstanceRequest(instanceId, bookmark, input);
+
+            try
+            {
+                await _workflowInvoker.InvokeAsync(request, cancellationToken);
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "An unhandled exception occured while processing the queue");
+            }
+        }
+    }
+}

src/runtime/Elsa.Runtime/Interpreters/TriggerWorkflowInstructionInterpreter.cs

@@ -13,12 +13,18 @@ public record TriggerWorkflowInstruction(WorkflowTrigger WorkflowTrigger, IDicti
 public class TriggerWorkflowInstructionInterpreter : WorkflowInstructionInterpreter<TriggerWorkflowInstruction>
 {
     private readonly IWorkflowInvoker _workflowInvoker;
+    private readonly IWorkflowDispatcher _workflowDispatcher;
     private readonly IWorkflowRegistry _workflowRegistry;
     private readonly ILogger _logger;
 
-    public TriggerWorkflowInstructionInterpreter(IWorkflowInvoker workflowInvoker, IWorkflowRegistry workflowRegistry, ILogger<TriggerWorkflowInstructionInterpreter> logger)
+    public TriggerWorkflowInstructionInterpreter(
+        IWorkflowInvoker workflowInvoker,
+        IWorkflowDispatcher workflowDispatcher,
+        IWorkflowRegistry workflowRegistry, 
+        ILogger<TriggerWorkflowInstructionInterpreter> logger)
     {
         _workflowInvoker = workflowInvoker;
+        _workflowDispatcher = workflowDispatcher;
         _workflowRegistry = workflowRegistry;
         _logger = logger;
     }
@@ -35,8 +41,8 @@ public class TriggerWorkflowInstructionInterpreter : WorkflowInstructionInterpre
             return null;
 
         // Execute workflow.
-        var executeRequest = new ExecuteWorkflowDefinitionRequest(workflowId, VersionOptions.Published, instruction.Input);
-        var workflowExecutionResult = await _workflowInvoker.ExecuteAsync(executeRequest, cancellationToken);
+        var executeRequest = new InvokeWorkflowDefinitionRequest(workflowId, VersionOptions.Published, instruction.Input);
+        var workflowExecutionResult = await _workflowInvoker.InvokeAsync(executeRequest, cancellationToken);
 
         return new ExecuteWorkflowInstructionResult(workflow, workflowExecutionResult);
     }
@@ -54,7 +60,7 @@ public class TriggerWorkflowInstructionInterpreter : WorkflowInstructionInterpre
 
         // Execute workflow.
         var dispatchRequest = new DispatchWorkflowDefinitionRequest(definitionId, VersionOptions.Published, instruction.Input);
-        await _workflowInvoker.DispatchAsync(dispatchRequest, cancellationToken);
+        await _workflowDispatcher.DispatchAsync(dispatchRequest, cancellationToken);
 
         return new DispatchWorkflowInstructionResult();
     }

src/runtime/Elsa.Runtime/Models/DispatchWorkflowDefinitionResponse.cs

@@ -0,0 +1,3 @@
+namespace Elsa.Runtime.Models;
+
+public record DispatchWorkflowDefinitionResponse();

src/runtime/Elsa.Runtime/Models/DispatchWorkflowInstanceResponse.cs

@@ -0,0 +1,3 @@
+namespace Elsa.Runtime.Models;
+
+public record DispatchWorkflowInstanceResponse();

src/runtime/Elsa.Runtime/Models/ExecuteWorkflowDefinitionRequest.cs

@@ -1,5 +0,0 @@
-using Elsa.Persistence.Models;
-
-namespace Elsa.Runtime.Models;
-
-public record ExecuteWorkflowDefinitionRequest(string DefinitionId, VersionOptions VersionOptions, IDictionary<string, object>? Input = default);

src/runtime/Elsa.Runtime/Models/ExecuteWorkflowInstanceRequest.cs

@@ -1,5 +0,0 @@
-using Elsa.Models;
-
-namespace Elsa.Runtime.Models;
-
-public record ExecuteWorkflowInstanceRequest(string InstanceId, Bookmark? Bookmark = default, IDictionary<string, object>? Input = default);

src/runtime/Elsa.Runtime/Models/InvokeWorkflowDefinitionRequest.cs

@@ -0,0 +1,5 @@
+using Elsa.Persistence.Models;
+
+namespace Elsa.Runtime.Models;
+
+public record InvokeWorkflowDefinitionRequest(string DefinitionId, VersionOptions VersionOptions, IDictionary<string, object>? Input = default);

src/runtime/Elsa.Runtime/Models/InvokeWorkflowInstanceRequest.cs

@@ -0,0 +1,5 @@
+using Elsa.Models;
+
+namespace Elsa.Runtime.Models;
+
+public record InvokeWorkflowInstanceRequest(string InstanceId, Bookmark? Bookmark = default, IDictionary<string, object>? Input = default);

src/runtime/Elsa.Runtime/Options/WorkflowRuntimeOptions.cs

@@ -1,11 +1,23 @@
 using Elsa.Runtime.Contracts;
+using Elsa.Runtime.Services;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace Elsa.Runtime.Options;
 
 public class WorkflowRuntimeOptions
 {
     /// <summary>
-    /// A list of workflow builders configured at application startup.
+    /// A list of workflow builders configured during application startup.
     /// </summary>
     public IDictionary<string, Func<IServiceProvider, IWorkflow>> Workflows { get; set; } = new Dictionary<string, Func<IServiceProvider, IWorkflow>>();
+
+    /// <summary>
+    /// A factory that instantiates a concrete <see cref="IWorkflowInvoker"/>.
+    /// </summary>
+    public Func<IServiceProvider, IWorkflowInvoker> WorkflowInvokerFactory { get; set; } = sp => ActivatorUtilities.CreateInstance<DefaultWorkflowInvoker>(sp);
+
+    /// <summary>
+    /// A factory that instantiates a concrete <see cref="IWorkflowDispatcher"/>.
+    /// </summary>
+    public Func<IServiceProvider, IWorkflowDispatcher> WorkflowDispatcherFactory { get; set; } = sp => ActivatorUtilities.CreateInstance<TaskBasedWorkflowDispatcher>(sp);
 }

src/runtime/Elsa.Runtime/Services/DefaultWorkflowInvoker.cs

@@ -0,0 +1,21 @@
+using Elsa.Models;
+using Elsa.Runtime.Contracts;
+using Elsa.Runtime.Models;
+
+namespace Elsa.Runtime.Services;
+
+/// <summary>
+/// A basic implementation that directly executes the specified workflow in local memory (as opposed elsewhere in some cluster).
+/// </summary>
+public class DefaultWorkflowInvoker : IWorkflowInvoker
+{
+    public Task<InvokeWorkflowResult> InvokeAsync(InvokeWorkflowDefinitionRequest request, CancellationToken cancellationToken = default)
+    {
+        throw new NotImplementedException();
+    }
+
+    public Task<InvokeWorkflowResult> InvokeAsync(InvokeWorkflowInstanceRequest request, CancellationToken cancellationToken = default)
+    {
+        throw new NotImplementedException();
+    }
+}

src/runtime/Elsa.Runtime/Services/TaskBasedWorkflowDispatcher.cs

@@ -0,0 +1,34 @@
+using System.Threading.Channels;
+using Elsa.Runtime.Contracts;
+using Elsa.Runtime.Models;
+
+namespace Elsa.Runtime.Services;
+
+/// <summary>
+/// A simple implementation that queues the specified request for workflow execution on a non-durable background worker.
+/// </summary>
+public class TaskBasedWorkflowDispatcher : IWorkflowDispatcher
+{
+    private readonly ChannelWriter<DispatchWorkflowDefinitionRequest> _workflowDefinitionChannelWriter;
+    private readonly ChannelWriter<DispatchWorkflowInstanceRequest> _workflowInstanceChannelWriter;
+
+    public TaskBasedWorkflowDispatcher(
+        ChannelWriter<DispatchWorkflowDefinitionRequest> workflowDefinitionChannelWriter,
+        ChannelWriter<DispatchWorkflowInstanceRequest> workflowInstanceChannelWriter)
+    {
+        _workflowDefinitionChannelWriter = workflowDefinitionChannelWriter;
+        _workflowInstanceChannelWriter = workflowInstanceChannelWriter;
+    }
+    
+    public async Task<DispatchWorkflowDefinitionResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, CancellationToken cancellationToken = default)
+    {
+        await _workflowDefinitionChannelWriter.WriteAsync(request, cancellationToken);
+        return new DispatchWorkflowDefinitionResponse();
+    }
+
+    public async Task<DispatchWorkflowInstanceResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, CancellationToken cancellationToken = default)
+    {
+        await _workflowInstanceChannelWriter.WriteAsync(request, cancellationToken);
+        return new DispatchWorkflowInstanceResponse();
+    }
+}

src/runtime/Elsa.Runtime/Services/WorkflowService.cs

@@ -8,38 +8,44 @@ namespace Elsa.Runtime.Services;
 public class WorkflowService : IWorkflowService
 {
     private readonly IWorkflowInvoker _workflowInvoker;
+    private readonly IWorkflowDispatcher _workflowDispatcher;
     private readonly IWorkflowInstructionExecutor _workflowInstructionExecutor;
     private readonly IStimulusInterpreter _stimulusInterpreter;
 
-    public WorkflowService(IWorkflowInvoker workflowInvoker, IWorkflowInstructionExecutor workflowInstructionExecutor, IStimulusInterpreter stimulusInterpreter)
+    public WorkflowService(
+        IWorkflowInvoker workflowInvoker,
+        IWorkflowDispatcher workflowDispatcher,
+        IWorkflowInstructionExecutor workflowInstructionExecutor, 
+        IStimulusInterpreter stimulusInterpreter)
     {
         _workflowInvoker = workflowInvoker;
+        _workflowDispatcher = workflowDispatcher;
         _workflowInstructionExecutor = workflowInstructionExecutor;
         _stimulusInterpreter = stimulusInterpreter;
     }
 
-    public async Task<ExecuteWorkflowResult> ExecuteWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> ExecuteWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
     {
-        var executeRequest = new ExecuteWorkflowDefinitionRequest(definitionId, versionOptions, input);
-        return await _workflowInvoker.ExecuteAsync(executeRequest, cancellationToken);
+        var executeRequest = new InvokeWorkflowDefinitionRequest(definitionId, versionOptions, input);
+        return await _workflowInvoker.InvokeAsync(executeRequest, cancellationToken);
     }
 
-    public async Task<ExecuteWorkflowResult> ExecuteWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
+    public async Task<InvokeWorkflowResult> ExecuteWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
     {
-        var request = new ExecuteWorkflowInstanceRequest(instanceId, bookmark, input);
-        return await _workflowInvoker.ExecuteAsync(request, cancellationToken);
+        var request = new InvokeWorkflowInstanceRequest(instanceId, bookmark, input);
+        return await _workflowInvoker.InvokeAsync(request, cancellationToken);
     }
 
-    public async Task<DispatchWorkflowResult> DispatchWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
+    public async Task<DispatchWorkflowDefinitionResponse> DispatchWorkflowAsync(string definitionId, VersionOptions versionOptions, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
     {
         var executeRequest = new DispatchWorkflowDefinitionRequest(definitionId, versionOptions, input);
-        return await _workflowInvoker.DispatchAsync(executeRequest, cancellationToken);
+        return await _workflowDispatcher.DispatchAsync(executeRequest, cancellationToken);
     }
 
-    public async Task<DispatchWorkflowResult> DispatchWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
+    public async Task<DispatchWorkflowInstanceResponse> DispatchWorkflowAsync(string instanceId, Bookmark bookmark, IDictionary<string, object>? input = default, CancellationToken cancellationToken = default)
     {
         var request = new DispatchWorkflowInstanceRequest(instanceId, bookmark, input);
-        return await _workflowInvoker.DispatchAsync(request, cancellationToken);
+        return await _workflowDispatcher.DispatchAsync(request, cancellationToken);
     }
 
     public async Task<IEnumerable<ExecuteWorkflowInstructionResult>> ExecuteStimulusAsync(IStimulus stimulus, CancellationToken cancellationToken = default)

src/samples/aspnet/Elsa.Samples.Web1/Elsa.Samples.Web1.csproj

@@ -6,11 +6,13 @@
     </PropertyGroup>
 
     <ItemGroup>
+        <ProjectReference Include="..\..\..\core\Elsa.ServiceBus.Abstractions\Elsa.ServiceBus.Abstractions.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.Activities\Elsa.Modules.Activities.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.AzureServiceBus\Elsa.Modules.AzureServiceBus.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.Hangfire\Elsa.Modules.Hangfire.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.Http\Elsa.Modules.Http.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.JavaScript\Elsa.Modules.JavaScript.csproj" />
+        <ProjectReference Include="..\..\..\modules\Elsa.Modules.MassTransit\Elsa.Modules.MassTransit.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.Scheduling\Elsa.Modules.Scheduling.csproj" />
         <ProjectReference Include="..\..\..\modules\Elsa.Modules.Quartz\Elsa.Modules.Quartz.csproj" />
         <ProjectReference Include="..\..\..\api\Elsa.Api\Elsa.Api.csproj" />