Resilience Notification Practice

This project is a practice-oriented simulation designed to demonstrate the implementation of resilient communication patterns in backend services using .NET and Polly.

The goal is to simulate how notification systems (e.g., Email, SMS, Push) can remain robust under failure, using resilience techniques such as:

• Retry (in case of transient failures)
• Timeout (to avoid hanging operations)
• Circuit Breaker (to stop calling unstable services)
• Fallback strategies (alternative communication channels)

📌 This project is not meant for production – it's a focused training tool to understand key backend resilience concepts and fault-handling strategies.

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Key Features

Resilience Strategies (via Polly)

• Retry: retries failed sends with exponential backoff
• Timeout: enforces maximum execution time per provider
• Circuit Breaker: temporarily disables unstable senders
• Wrap: combines all policies together for layered protection

Notification Dispatcher

• Dispatches notifications to multiple providers
• Supports fallbacks when primary channels fail
• Randomized failure simulation to trigger Polly behaviors

Multi-Provider Architecture

• Supports multiple channels:
  • Email
  • SMS
  • Push
• Each implements a common ISender interface

Clean Dependency Injection

• Providers are injected with their policies
• Policy is shared but abstracted for better testability

Structured Logging with [LoggerMessage]

• Logs retries, failures, fallbacks and successes
• Easily customizable and high-performance

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🧪 How to Test

1. Run the project:

   dotnet run
   

2. Send a POST request using Postman or an .http file

    POST http://localhost:{port}/api/notification
   {
       "receiver": "hossein@example.com",
       "message": "Hello world!",
       "methods": [ 0, 1 ],
       "fallbacks": [ 2 ]
   }

3. Check for Logs

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📦 Project Structure

resilience-notification-practice/
├── API/
│   └── NotificationEndpoints.cs
├── Core/
│   ├── Dispatchers/
│   ├── Interfaces/
│   │   └── ISender.cs
│   ├── Models/
│   │   ├── Enums/
│   │   └── NotificationRequest.cs
│   ├── Senders/
│   │   ├── Email/
│   │   ├── Sms/
│   │   └── Push/
│   └── Services/
│       └── NotificationSenderResolver.cs
├── DTOs/
│   ├── Requests/
│   └── Responses/
├── Infrastructure/
│   ├── Log/
│   │   └── NotificationLogTemplate.cs
│   └── Resilience/
│       └── NotificationPollyPolicies.cs