.NET Samples - Create 03-workflows learning path step (#4102)

dotnet/samples/03-workflows/HumanInTheLoop/HumanInTheLoopBasic/HumanInTheLoopBasic.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>net10.0</TargetFrameworks>
+
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\src\Microsoft.Agents.AI.Workflows\Microsoft.Agents.AI.Workflows.csproj" />
+  </ItemGroup>
+
+</Project>

dotnet/samples/03-workflows/HumanInTheLoop/HumanInTheLoopBasic/Program.cs

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+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Agents.AI.Workflows;
+
+namespace WorkflowHumanInTheLoopBasicSample;
+
+/// <summary>
+/// This sample introduces the concept of RequestPort and ExternalRequest to enable
+/// human-in-the-loop interaction scenarios.
+/// A request port can be used as if it were an executor in the workflow graph. Upon receiving
+/// a message, the request port generates an RequestInfoEvent that gets emitted to the external world.
+/// The external world can then respond to the request by sending an ExternalResponse back to
+/// the workflow.
+/// The sample implements a simple number guessing game where the external user tries to guess
+/// a pre-defined target number. The workflow consists of a single JudgeExecutor that judges
+/// the user's guesses and provides feedback.
+/// </summary>
+/// <remarks>
+/// Pre-requisites:
+/// - Foundational samples should be completed first.
+/// </remarks>
+public static class Program
+{
+    private static async Task Main()
+    {
+        // Create the workflow
+        var workflow = WorkflowFactory.BuildWorkflow();
+
+        // Execute the workflow
+        await using StreamingRun handle = await InProcessExecution.StreamAsync(workflow, NumberSignal.Init);
+        await foreach (WorkflowEvent evt in handle.WatchStreamAsync())
+        {
+            switch (evt)
+            {
+                case RequestInfoEvent requestInputEvt:
+                    // Handle `RequestInfoEvent` from the workflow
+                    ExternalResponse response = HandleExternalRequest(requestInputEvt.Request);
+                    await handle.SendResponseAsync(response);
+                    break;
+
+                case WorkflowOutputEvent outputEvt:
+                    // The workflow has yielded output
+                    Console.WriteLine($"Workflow completed with result: {outputEvt.Data}");
+                    return;
+            }
+        }
+    }
+
+    private static ExternalResponse HandleExternalRequest(ExternalRequest request)
+    {
+        if (request.DataIs<NumberSignal>())
+        {
+            switch (request.DataAs<NumberSignal>())
+            {
+                case NumberSignal.Init:
+                    int initialGuess = ReadIntegerFromConsole("Please provide your initial guess: ");
+                    return request.CreateResponse(initialGuess);
+                case NumberSignal.Above:
+                    int lowerGuess = ReadIntegerFromConsole("You previously guessed too large. Please provide a new guess: ");
+                    return request.CreateResponse(lowerGuess);
+                case NumberSignal.Below:
+                    int higherGuess = ReadIntegerFromConsole("You previously guessed too small. Please provide a new guess: ");
+                    return request.CreateResponse(higherGuess);
+            }
+        }
+
+        throw new NotSupportedException($"Request {request.PortInfo.RequestType} is not supported");
+    }
+
+    private static int ReadIntegerFromConsole(string prompt)
+    {
+        while (true)
+        {
+            Console.Write(prompt);
+            string? input = Console.ReadLine();
+            if (int.TryParse(input, out int value))
+            {
+                return value;
+            }
+            Console.WriteLine("Invalid input. Please enter a valid integer.");
+        }
+    }
+}

dotnet/samples/03-workflows/HumanInTheLoop/HumanInTheLoopBasic/WorkflowFactory.cs

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+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.Agents.AI.Workflows;
+
+namespace WorkflowHumanInTheLoopBasicSample;
+
+internal static class WorkflowFactory
+{
+    /// <summary>
+    /// Get a workflow that plays a number guessing game with human-in-the-loop interaction.
+    /// An input port allows the external world to provide inputs to the workflow upon requests.
+    /// </summary>
+    internal static Workflow BuildWorkflow()
+    {
+        // Create the executors
+        RequestPort numberRequestPort = RequestPort.Create<NumberSignal, int>("GuessNumber");
+        JudgeExecutor judgeExecutor = new(42);
+
+        // Build the workflow by connecting executors in a loop
+        return new WorkflowBuilder(numberRequestPort)
+            .AddEdge(numberRequestPort, judgeExecutor)
+            .AddEdge(judgeExecutor, numberRequestPort)
+            .WithOutputFrom(judgeExecutor)
+            .Build();
+    }
+}
+
+/// <summary>
+/// Signals used for communication between guesses and the JudgeExecutor.
+/// </summary>
+internal enum NumberSignal
+{
+    Init,
+    Above,
+    Below,
+}
+
+/// <summary>
+/// Executor that judges the guess and provides feedback.
+/// </summary>
+internal sealed class JudgeExecutor() : Executor<int>("Judge")
+{
+    private readonly int _targetNumber;
+    private int _tries;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="JudgeExecutor"/> class.
+    /// </summary>
+    /// <param name="targetNumber">The number to be guessed.</param>
+    public JudgeExecutor(int targetNumber) : this()
+    {
+        this._targetNumber = targetNumber;
+    }
+
+    public override async ValueTask HandleAsync(int message, IWorkflowContext context, CancellationToken cancellationToken = default)
+    {
+        this._tries++;
+        if (message == this._targetNumber)
+        {
+            await context.YieldOutputAsync($"{this._targetNumber} found in {this._tries} tries!", cancellationToken);
+        }
+        else if (message < this._targetNumber)
+        {
+            await context.SendMessageAsync(NumberSignal.Below, cancellationToken: cancellationToken);
+        }
+        else
+        {
+            await context.SendMessageAsync(NumberSignal.Above, cancellationToken: cancellationToken);
+        }
+    }
+}