AsyncAwaitFanOut (.NET 8 + C#)

A clean and modern .NET 8 solution showcasing async/await, bounded concurrency, timeouts, and partial success handling using Task.WhenAll and SemaphoreSlim.
This project demonstrates resilient orchestration patterns for fan-out scenarios involving multiple I/O-bound services.

Features

• ⚙️ Async/Await orchestration — fully non-blocking (Task.WhenAll, no .Result / .Wait()).
• 🚦 Bounded concurrency with SemaphoreSlim to limit parallelism.
• ⏱️ Per-call timeouts combined with a global CancellationToken.
• 💥 Partial success handling: collects individual errors without aborting the batch.
• 🧩 Clean architecture split into Core / ConsoleApp / Tests.
• 🧪 Unit tests with xUnit.
• 🤖 Continuous Integration via GitHub Actions.

Project Structure

AsyncAwaitFanOut/
├─ AsyncAwaitFanOut.sln
├─ AsyncAwaitFanOut.ConsoleApp/  # Console demo (entry point)
├─ AsyncAwaitFanOut.Core/
│  ├─ DTOs/                      # Domain transfer objects
│  ├─ Interfaces/                # Contracts for external services
│  └─ Services/                  # Business logic (OrderSnapshotService, mocks)
└─ AsyncAwaitFanOut.Tests/       # Unit tests with xUnit

Getting Started

1) Build & Test

dotnet build
dotnet test

2) Run the Console App

dotnet run --project AsyncAwaitFanOut.ConsoleApp

Example Output

=== Order Snapshots ===
- 23f0a3c5 :: Order? yes, Payment? yes, Shipment? yes :: OK
- 9d8b1e22 :: Order? yes, Payment? no, Shipment? yes :: PaymentService: timeout
- 7fa43b0a :: Order? yes, Payment? yes, Shipment? yes :: OK

Done.

Architecture Notes

• OrderSnapshotService orchestrates all external calls, enforcing throttling and timeouts.
• SafeCall wrapper merges per-call timeout with the outer cancellation token.
• Services simulate I/O latency (1–3s range) to illustrate concurrency patterns.
• Error handling follows partial success design — failures are logged in each snapshot’s error list.

License

This project is licensed under the MIT License. See LICENSE for details.