.NET: [Feature Branch] Add basic durable workflow support (#3648)

* Add basic durable workflow support. * PR feedback fixes * Add conditional edge sample. * PR feedback fixes. * Minor cleanup. * Minor cleanup * Minor formatting improvements. * Improve comments/documentation on the execution flow.
2026-06-16 21:04:09 +08:00 · 2026-02-06 16:02:42 -08:00
parent 98cd72839e
commit e8d0bd9051
54 changed files with 4863 additions and 505 deletions
@@ -0,0 +1,98 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// Example: Given this workflow graph with a fan-out from B and a fan-in at E,
+// plus a conditional edge from B to D:
+//
+//     [A] ──► [B] ──► [C] ──► [E]
+//              │               ▲
+//              └──► [D] ──────┘
+//                (condition:
+//                 x => x.NeedsReview)
+//
+// WorkflowAnalyzer.BuildGraphInfo() produces:
+//
+//  StartExecutorId = "A"
+//
+//  Successors (who does each executor send output to?):
+//  ┌──────────┬──────────────┐
+//  │ "A"      │ ["B"]        │
+//  │ "B"      │ ["C", "D"]   │  ◄── fan-out: B sends to both C and D
+//  │ "C"      │ ["E"]        │
+//  │ "D"      │ ["E"]        │
+//  │ "E"      │ []           │  ◄── terminal: no successors
+//  └──────────┴──────────────┘
+//
+//  Predecessors (who feeds into each executor?):
+//  ┌──────────┬──────────────┐
+//  │ "A"      │ []           │  ◄── start: no predecessors
+//  │ "B"      │ ["A"]        │
+//  │ "C"      │ ["B"]        │
+//  │ "D"      │ ["B"]        │
+//  │ "E"      │ ["C", "D"]   │  ◄── fan-in: count=2, messages will be aggregated
+//  └──────────┴──────────────┘
+//
+//  EdgeConditions (which edges have routing conditions?):
+//  ┌──────────────────┬──────────────────────────┐
+//  │ ("B", "D")       │ x => x.NeedsReview       │  ◄── D only receives if condition is true
+//  └──────────────────┴──────────────────────────┘
+//  (The B→C edge has no condition, so C always receives B's output.)
+//
+//  ExecutorOutputTypes (what type does each executor return?):
+//  ┌──────────┬──────────────────┐
+//  │ "A"      │ typeof(string)   │  ◄── used by DurableDirectEdgeRouter to deserialize
+//  │ "B"      │ typeof(Order)    │      the JSON message for condition evaluation
+//  │ "C"      │ typeof(Report)   │
+//  │ "D"      │ typeof(Report)   │
+//  │ "E"      │ typeof(string)   │
+//  └──────────┴──────────────────┘
+//
+// DurableEdgeMap then consumes this to build the runtime routing layer.
+
+using System.Diagnostics;
+
+namespace Microsoft.Agents.AI.DurableTask.Workflows;
+
+/// <summary>
+/// Represents the workflow graph structure needed for message-driven execution.
+/// </summary>
+/// <remarks>
+/// <para>
+/// This is a simplified representation that contains only the information needed
+/// for routing messages between executors during superstep execution:
+/// </para>
+/// <list type="bullet">
+/// <item><description>Successors for routing messages forward</description></item>
+/// <item><description>Predecessors for detecting fan-in points</description></item>
+/// <item><description>Edge conditions for conditional routing</description></item>
+/// <item><description>Output types for deserialization during condition evaluation</description></item>
+/// </list>
+/// </remarks>
+[DebuggerDisplay("Start = {StartExecutorId}, Executors = {Successors.Count}")]
+internal sealed class WorkflowGraphInfo
+{
+    /// <summary>
+    /// Gets or sets the starting executor ID for the workflow.
+    /// </summary>
+    public string StartExecutorId { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Maps each executor ID to its successors (for message routing).
+    /// </summary>
+    public Dictionary<string, List<string>> Successors { get; } = [];
+
+    /// <summary>
+    /// Maps each executor ID to its predecessors (for fan-in detection).
+    /// </summary>
+    public Dictionary<string, List<string>> Predecessors { get; } = [];
+
+    /// <summary>
+    /// Maps edge connections (sourceId, targetId) to their condition functions.
+    /// The condition function takes the predecessor's result and returns true if the edge should be followed.
+    /// </summary>
+    public Dictionary<(string SourceId, string TargetId), Func<object?, bool>?> EdgeConditions { get; } = [];
+
+    /// <summary>
+    /// Maps executor IDs to their output types (for proper deserialization during condition evaluation).
+    /// </summary>
+    public Dictionary<string, Type?> ExecutorOutputTypes { get; } = [];
+}