.NET: Update Workflow Input/Output Redesign (#881)

* feat: Make Executor id field mandatory

When checkpointing is involved, it is critical to keep executor ids consistent between runs, even when recreating a new object tree for the workflow.

The default id-setting mechanism generated a guid for part of the id, making it not work when restoring from a checkpoint.

This change prevents this situation from arising.

* feat: Enable running untyped Workflows

With the change to enable delay-instantiation of executors and support for async Executor factory methods, we must instantiate the starting executor to know what are the valid input types for the workflow.

To avoid forcing instantiation every time, and to better support workflows with multiple input types, we enable support for build and interacting with the base Workflow type without type annotations, and remove the requirement to know a valid input type when initiating a run.

* feat: Support Output from any executor and multiple outputs.

dotnet/samples/GettingStarted/Workflows/Agents/WorkflowAsAnAgent/Program.cs

@@ -38,7 +38,7 @@ public static class Program
         var chatClient = new AzureOpenAIClient(new Uri(endpoint), new AzureCliCredential()).GetChatClient(deploymentName).AsIChatClient();
 
         // Create the workflow and turn it into an agent
-        var workflow = WorkflowHelper.GetWorkflow(chatClient);
+        var workflow = await WorkflowHelper.GetWorkflowAsync(chatClient).ConfigureAwait(false);
         var agent = workflow.AsAgent("workflow-agent", "Workflow Agent");
         var thread = agent.GetNewThread();
 

dotnet/samples/GettingStarted/Workflows/Agents/WorkflowAsAnAgent/WorkflowHelper.cs

@@ -17,7 +17,7 @@ internal static class WorkflowHelper
     /// </summary>
     /// <param name="chatClient">The chat client to use for the agents</param>
     /// <returns>A workflow that processes input using two language agents</returns>
-    internal static Workflow<List<ChatMessage>> GetWorkflow(IChatClient chatClient)
+    internal static ValueTask<Workflow<List<ChatMessage>>> GetWorkflowAsync(IChatClient chatClient)
     {
         // Create executors
         var startExecutor = new ConcurrentStartExecutor();
@@ -29,7 +29,8 @@ internal static class WorkflowHelper
         return new WorkflowBuilder(startExecutor)
             .AddFanOutEdge(startExecutor, targets: [frenchAgent, englishAgent])
             .AddFanInEdge(aggregationExecutor, sources: [frenchAgent, englishAgent])
-            .Build<List<ChatMessage>>();
+            .WithOutputFrom(aggregationExecutor)
+            .BuildAsync<List<ChatMessage>>();
     }
 
     /// <summary>
@@ -84,7 +85,7 @@ internal static class WorkflowHelper
             if (this._messages.Count == 2)
             {
                 var formattedMessages = string.Join(Environment.NewLine, this._messages.Select(m => $"{m.Text}"));
-                await context.AddEventAsync(new WorkflowCompletedEvent(formattedMessages));
+                await context.YieldOutputAsync(formattedMessages);
             }
         }
     }