implementing-pubsub-pattern

# .NET Pub-Sub Pattern A guide for Pub-Sub patterns for event-based asynchronous communication. **Quick Reference:** See [QUICKREF.md](QUICKREF.md) for essential patterns at a glance. ## 1. Core APIs | API | Purpose | NuGet | |-----|---------|-------| | `System.Reactive` (Rx.NET) | Reactive event streams | System.Reactive | | `System.Threading.Channels` | Async Producer-Consumer | BCL | | `IObservable<T>` | Observable sequence | BCL | --- ## 2. System.Threading.Channels ### 2.1 Basic Usage ```csharp using System.Threading.Channels; public sealed class MessageProcessor { private readonly Channel<Message> _channel = Channel.CreateUnbounded<Message>(); // Producer - Send message public async Task SendAsync(Message message) { await _channel.Writer.WriteAsync(message); } // Consumer - Process message public async Task ProcessAsync(CancellationToken ct) { await foreach (var message in _channel.Reader.ReadAllAsync(ct)) { await HandleMessage(message); } } // Channel completion signal public void Complete() => _channel.Writer.Complete(); } ``` ### 2.2 Bounded Channel (Backpressure Control) ```csharp // Backpressure control with buffer size limit var options = new BoundedChannelOptions(capacity: 100) { FullMode = BoundedChannelFullMode.Wait, // Wait when full SingleReader = true, SingleWriter = false }; var channel = Channel.CreateBounded<Message>(options); // Wri...