🐘🎯 Hexagonal Architecture, DDD & CQRS in PHP Symfony

Example of a PHP application following Domain-Driven Design (DDD) and Command Query Responsibility Segregation (CQRS) principles keeping the code as simple as possible.

Take a look, play and have fun with this. Stars are welcomed 😊

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Table of Contents

• 🚀 Environment setup
  • 🐳 Needed tools
  • 🛠️ Environment configuration
  • 🌍 Application execution
  • ✅ Tests execution
• 🤔 Project explanation
  • Bounded Contexts
  • Hexagonal Architecture
  • Aggregates
  • Command Bus
  • Query Bus
  • Event Bus
• 🤝 Contributing
• 🤩 Extra

🚀 Environment setup

🐳 Needed tools

1. Install Docker
2. Clone this project: git clone https://github.com/CodelyTV/cqrs-ddd-php-example cqrs-ddd-php-example
3. Move to the project folder: cd cqrs-ddd-php-example

🛠️ Environment configuration

1. Copy the default environment variables: cp .env.dist .env
2. Modify the environment variables if needed: vim .env
3. Add api.codelytv.localhost domain to your local hosts: echo "127.0.0.1 api.codelytv.localhost"| sudo tee -a /etc/hosts > /dev/null

🌍 Application execution

1. Install PHP dependencies and bring up the project Docker containers with Docker Compose: make build
2. Go to the API health check page

✅ Tests execution

1. Install PHP dependencies if you haven't done so: make deps
2. Execute Behat and PHP Unit tests: make test

🤔 Project explanation

This project tries to be a MOOC (Massive Open Online Course) platform. For now it only has an API and some Consumers.

⛱️ Bounded Contexts

• Mooc: Place to look in if you wanna see some code 🙂. Massive Open Online Courses public platform with users, videos, notifications, and so on
• Backoffice: Work in progress. Here you'll find the use cases needed by the Customer Support department in order to manage users, courses, videos, and so on.

🎯 Hexagonal Architecture

This repository follow the Hexagonal Architecture pattern. Also is structured using modules. With this, we can see that the current structure of a Bounded Context is:

$ tree -L 4 src

src
|-- Mooc // Company subdomain / Bounded Context: Features related to one of the company business lines / products
|   `-- Videos // Some Module inside the Mooc context
|       |-- Application
|       |   |-- Create // Inside the application layer all is structured by actions
|       |   |   |-- CreateVideoCommand.php
|       |   |   |-- CreateVideoCommandHandler.php
|       |   |   `-- VideoCreator.php
|       |   |-- Find
|       |   |-- Trim
|       |   `-- Update
|       |-- Domain
|       |   |-- Video.php // The Aggregate of the Module
|       |   |-- VideoCreatedDomainEvent.php // A Domain Event
|       |   |-- VideoFinder.php
|       |   |-- VideoId.php
|       |   |-- VideoNotFound.php
|       |   |-- VideoRepository.php // The `Interface` of the repository is inside Domain
|       |   |-- VideoTitle.php
|       |   |-- VideoType.php
|       |   |-- VideoUrl.php
|       |   `-- Videos.php // A collection of our Aggregate
|       `-- Infrastructure // The infrastructure of our module
|           |-- DependencyInjection
|           `-- Persistence
|               `--VideoRepositoryMySql.php // An implementation of the repository
`-- Shared // Shared Kernel: Common infrastructure and domain shared between the different Bounded Contexts
    |-- Domain
    `-- Infrastructure

Repository pattern

Our repositories try to be as simple as possible usually only containing 2 methods search and save. If we need some query with more filters we use the Strategy pattern also known as Criteria pattern. So we add a searchByCriteria method.

You can see an example here and its implementation here.

Aggregates

You can see an example of an aggregate here. All aggregates should extends the AggregateRoot.

Command Bus

There are 2 implementations of the command bus.

1. Sync using the Symfony Message Bus
2. Async using a local file

Query Bus

The Query Bus uses the Symfony Message Bus.

Event Bus

The Event Bus uses the Symfony Message Bus.

🤔 Contributing

There are some things missing (add swagger, improve documentation...), feel free to add this if you want! If you want some guidelines feel free to contact us :)

🤩 Extra

This code was show in the From framework coupled code to #microservices through #DDD talk and doubts where answered in DDD y CQRS: Preguntas Frecuentes video.

🎥 Used in the CodelyTV Pro courses:

• 🇪🇸 Arquitectura Hexagonal
• 🇪🇸 CQRS: Command Query Responsibility Segregation
• 🇪🇸 Comunicación entre microservicios: Event-Driven Architecture