Simple Notification API

🎯 Overview

This project implements a notification system with the following capabilities:

• Create email notifications via REST API
• List all notifications
• Send notifications asynchronously using Symfony Messenger
• Automatic retry mechanism on failure
• Proper error handling and logging

✨ Features

• RESTful API with JSON responses
• Asynchronous email sending via Symfony Messenger
• Status tracking: pending, sent, failed
• Automatic retry up to 3 attempts
• Input validation with detailed error messages
• OpenAPI/Swagger documentation at /api/doc
• Comprehensive test suite
• Clean architecture with domain services and DTOs

🏗️ Architecture principles

• Domain-Driven Design: Business logic split into domain services
• SOLID principles: Single responsibility, dependency injection
• DTO pattern: Clean separation between API contracts and entities
• Event-driven architecture: Asynchronous processing with Symfony Messenger

📦 Technical stack

• PHP 8.2+
• Symfony 7.3+
• PostgreSQL 16+
• Docker & Docker Compose (optional)

🚀 Installation

1. Clone the repository

git clone https://github.com/TheoMoriceEM/Simple-Notification-API.git
cd Simple-Notification-API

2. Start Docker containers (optional)

docker compose up -d

3. Install dependencies

docker exec -it simple-notification-api-php-1 composer install

4. Setup database

# Create database
docker exec -it simple-notification-api-php-1 php bin/console doctrine:database:create

# Run migrations
docker exec -it simple-notification-api-php-1 php bin/console doctrine:migrations:migrate

# Setup Messenger transport tables
docker exec -it simple-notification-api-php-1 php bin/console messenger:setup-transports

5. Start the Messenger worker

docker exec -it simple-notification-api-php-1 php bin/console messenger:consume async

The API is now available at http://localhost
And the Swagger UI at: http://localhost/api/doc

🧪 Testing

Run Tests

# Setup test database
docker exec -it simple-notification-api-php-1 php bin/console doctrine:database:create --env=test
docker exec -it simple-notification-api-php-1 php bin/console doctrine:schema:create --env=test

# Run all tests
docker exec -it simple-notification-api-php-1 php bin/phpunit

🤔 Technical Decisions

1. Asynchronous Processing with Symfony Messenger

Why

Sending emails synchronously can block HTTP requests and degrade the user experience.

Consequences

✅ Fast API responses
✅ Automatic retry on failure
✅ Horizontal scalability
⚠️ Requires running worker process
⚠️ Data consistency (e.g. status updates are async)

2. Domain Service Layer

Why

Separate business logic from HTTP concerns.

Benefits

✅ Reusable across controllers, CLI commands, and tests
✅ Easier to test (no HTTP mocking needed)

3. DTO Pattern

Why

Decouple API contracts from database entities.

Implementation

• NotificationValidation for input validation
• NotificationDto for responses
• Static method create() for conversion from entity

4. Email Service Abstraction

Why

Separate email sending logic from message handling.

Benefits

✅ Easy to swap email providers
✅ Testable in isolation
✅ Reusable across the application
✅ Single responsibility principle

5. OpenAPI Documentation

Why

Interactive API documentation for developers.

Benefits

✅ Always up-to-date with code
✅ Interactive testing via Swagger UI
✅ Clear API contract

📝 Notes

Email Sending Simulation

For this technical test, email sending is simulated with:

• A 3-second delay (mimics usual latency)
• A 10% random failure rate (tests retry mechanism)

⚠️ Beware that due to this delay and the asynchronous processing of notifications, the /send API requests will return inconsistent data:

• The status will still be pending although it will switch either to sent or failed 3 seconds later.
• The sentAt timestamp will be undefined although if the sending succeeds, it will be set 3 seconds later as well.