dddshelf / cheeper-ddd-cqrs-example

Cheeper is the reference code implementation of the book "CQRS By Example" – https://leanpub.com/cqrs-by-example/

Hexagonal Architecture + DDD + CQRS by Example Book code repository

Cheeper is a Twitter clone used in the book CQRS By Example as a reference implementation. Here you will find an example of applying Hexagonal Architecture, DDD (tactical patterns) and CQRS (Command query responsibility segregation) in a real use case PHP application.

Take a look around, play a bit with the code, and if you like what you see ... Give us a star 💫

📕 Check out the book · Report an issue in the book · Report an issue in the code

Table of contents

• About the book
• Code structure
  • The App namespace
  • The Cheeper namespace
• Running the application
  • Requirements
  • Getting started
  • Set all the infrastructure up
  • Demo time!
    • 1. Followers counter query
    • 2. Author timeline
    • 3. Adding authors
    • 4. Consuming events
    • 5. Follower counters query
    • 6. Author timeline again
    • 7. Following other authors
    • 8. Consuming events again
    • 9. Follower counters query
    • 10. Posting cheeps
    • 11. Author timeline

About the Book

Command-Query Responsibility Segregation is an architectural style for developing applications that split the Domain Model in Read and Write operations in order to maximize semantics, performance, and scalability. What are all the benefits of CQRS? What are the drawbacks? In which cases does it worth applying it? How does it relate to Hexagonal Architecture? How do we properly implement the Write Model and Read Models? How do we keep in sync both sides? What are the following steps to move towards Event Sourcing? This book will answer all these questions and many more, guided through lots of practical examples. Brought to you by the same authors behind "Domain-Driven Design in PHP".

Do you want to know more? Do you want to grasp further details about CQRS?

🌟 Go checkout the book 🌟

Code Structure

This repository follows a typical PHP application layout: All the code lives in the src folder and classes map 1:1 with the file where they live, following the PSR-4 standard for class autoloading.

The App namespace

This namespace contains all the classes that are specific to the delivery mechanism. In this case the delivery mechanism is the Symfony framework following the recommended structure.

The Cheeper namespace

The Cheeper namespaces is a bit little different from a typical PHP application using tactical Domain-Driven design patterns, where you could expect several modules under the Cheeper namespace. In here you will find book-chapter namespaces instead of modules, so it's easy for you to navigate through all the code of each chapter.

src/Cheeper
├── AllChapters
│   ├── Application
│   ├── DomainModel
│   └── Infrastructure
├── Chapter2
│   ├── Author.php
│   ├── Cheep.php
│   ├── Hexagonal
│   ├── Layered
│   └── Spaghetti
├── Chapter4
│   ├── Application
│   ├── DomainModel
│   └── Infrastructure
├── Chapter5
│   ├── Application
│   └── Infrastructure
├── Chapter6
│   ├── Application
│   └── Infrastructure
├── Chapter7
│   ├── Application
│   ├── DomainModel
│   └── Infrastructure
├── Chapter8
│   ├── Application
│   ├── DomainModel
│   └── Infrastructure
└── Chapter9
    ├── DomainModel
    └── Infrastructure

Running the application

Requirements

• Docker 👉 To run all services in your computer without installing all the dependencies.
• Docker Compose 👉 To orchestrate the services. If you're on Mac or Windows and you have installed Docker Desktop you already have Docker Compose installed. If you're on Linux, you can check out installation here.
• HTTPie 👉 To make HTTP requests in the same way as they're done in this README file.

Getting started

The first thing you should do is to have a fresh copy of the code. To do so just clone the repository

git clone https://github.com/dddshelf/cheeper-ddd-cqrs-example

Then, in order to get environment set up properly, you should have a .env.local file with all the correct values 👇

cp .env.docker.dist .env.local

And you're ready to go! 🤘

Set all the infrastructure up

As the code runs fully on docker, several make targets have been carefully prepared in order to make the interaction with the code as easy and smooth as possible. To start all the services just run 👇

make start

This make target, runs docker compose, and ensures all services are up and running. Next, once all the services have been started, we must make sure the database and queues start empty and database migrations are executed successfully. To do so, just run

make infrastructure

Finally to stop all services just run

make stop

Now you're ready to execute all the demo steps! 🚀

Demo time!

Cheeper starts totally as a blank application. There is no Author, Cheeps, Follows, etc.

1. Follower Counters Query

http --json --body http://127.0.0.1:8000/chapter7/author/a64a52cc-3ee9-4a15-918b-099e18b43119/followers-counter
http --json --body http://127.0.0.1:8000/chapter7/author/1fd7d739-2ad7-41a8-8c18-565603e3733f/followers-counter
http --json --check-status --body http://127.0.0.1:8000/chapter7/author/1da1366f-b066-4514-9b29-7346df41e371/followers-counter

Expected output

{
    "data": {
        "message": "Author \"a64a52cc-3ee9-4a15-918b-099e18b43119\" does not exist"
    },
    "meta": {
        "message_id": "c0342dfe-782e-4ffa-9e9c-8d6d82533ab2"
    }
}

{
    "data": {
        "message": "Author \"1fd7d739-2ad7-41a8-8c18-565603e3733f\" does not exist"
    },
    "meta": {
        "message_id": "35089f63-53ca-4a44-9a7c-6e588ba6d885"
    }
}

{
    "data": {
        "message": "Author \"1da1366f-b066-4514-9b29-7346df41e371\" does not exist"
    },
    "meta": {
        "message_id": "d07a6984-abc9-4a3a-92bb-829ad5dd85df"
    }
}

2. Author Timeline

http --json --body http://127.0.0.1:8000/chapter7/author/a64a52cc-3ee9-4a15-918b-099e18b43119/timeline
http --json --body http://127.0.0.1:8000/chapter7/author/1fd7d739-2ad7-41a8-8c18-565603e3733f/timeline
http --json --body http://127.0.0.1:8000/chapter7/author/1da1366f-b066-4514-9b29-7346df41e371/timeline

Expected output

{
    "_meta": [],
    "data": "Author \"1da1366f-b066-4514-9b29-7346df41e371\" does not exist"
}

3. Adding Authors

http --json --body POST http://127.0.0.1:8000/chapter7/author author_id="a64a52cc-3ee9-4a15-918b-099e18b43119" username="bob" email="[email protected]"
http --json --body POST http://127.0.0.1:8000/chapter7/author author_id="1fd7d739-2ad7-41a8-8c18-565603e3733f" username="alice" email="[email protected]"
http --json --body POST http://127.0.0.1:8000/chapter7/author author_id="1da1366f-b066-4514-9b29-7346df41e371" username="charlie" email="[email protected]"

Expected output

{
    "author_id": "a64a52cc-3ee9-4a15-918b-099e18b43119",
    "message_id": "d3c90181-c2c1-4e5c-90e9-99a799197b88"
}

4. Consuming Events

php bin/console messenger:consume events_async

Expected output

08:59:13 INFO      [messenger] Received message Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned"]
08:59:13 INFO      [messenger] Message Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned handled by Cheeper\Chapter7\Infrastructure\Application\Author\Event\SymfonyNewAuthorSignedEventHandler::handle ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned","handler" => "Cheeper\Chapter7\Infrastructure\Application\Author\Event\SymfonyNewAuthorSignedEventHandler::handle"]
08:59:13 INFO      [messenger] Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned was handled successfully (acknowledging to transport). ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned"]
08:59:13 INFO      [messenger] Received message Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned"]
08:59:13 INFO      [messenger] Message Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned handled by Cheeper\Chapter7\Infrastructure\Application\Author\Event\SymfonyNewAuthorSignedEventHandler::handle ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned","handler" => "Cheeper\Chapter7\Infrastructure\Application\Author\Event\SymfonyNewAuthorSignedEventHandler::handle"]
08:59:13 INFO      [messenger] Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned was handled successfully (acknowledging to transport). ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned"]
08:59:13 INFO      [messenger] Received message Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned"]
08:59:13 INFO      [messenger] Message Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned handled by Cheeper\Chapter7\Infrastructure\Application\Author\Event\SymfonyNewAuthorSignedEventHandler::handle ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned","handler" => "Cheeper\Chapter7\Infrastructure\Application\Author\Event\SymfonyNewAuthorSignedEventHandler::handle"]
08:59:13 INFO      [messenger] Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned was handled successfully (acknowledging to transport). ["message" => Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned^ { …},"class" => "Cheeper\Chapter7\DomainModel\Author\NewAuthorSigned"]

5. Follower Counters Query

http --json --body http://127.0.0.1:8000/chapter7/author/a64a52cc-3ee9-4a15-918b-099e18b43119/followers-counter
http --json --body http://127.0.0.1:8000/chapter7/author/1fd7d739-2ad7-41a8-8c18-565603e3733f/followers-counter
http --json --body http://127.0.0.1:8000/chapter7/author/1da1366f-b066-4514-9b29-7346df41e371/followers-counter

Expected output

{
    "_meta": {
        "message_id": "8db6fc1d-41d5-4f6b-8950-e5766eee53e9"
    },
    "data": {
        "authorId": "1da1366f-b066-4514-9b29-7346df41e371",
        "authorUsername": "charlie",
        "numberOfFollowers": 0
    }
}

6. Author Timeline again

http --json --body http://127.0.0.1:8000/chapter7/author/a64a52cc-3ee9-4a15-918b-099e18b43119/timeline
http --json --body http://127.0.0.1:8000/chapter7/author/1fd7d739-2ad7-41a8-8c18-565603e3733f/timeline
http --json --body http://127.0.0.1:8000/chapter7/author/1da1366f-b066-4514-9b29-7346df41e371/timeline

Expected output

{
    "cheeps": []
}

7. Following other Authors

http --json --body POST http://127.0.0.1:8000/chapter7/follow follow_id="8cc71bf2-f827-4c92-95a5-43bb1bc622ad" from_author_id="1fd7d739-2ad7-41a8-8c18-565603e3733f" to_author_id="a64a52cc-3ee9-4a15-918b-099e18b43119"
http --json --body POST http://127.0.0.1:8000/chapter7/follow follow_id="f3088920-841e-4577-a3c2-efdc80f0dea5" from_author_id="1da1366f-b066-4514-9b29-7346df41e371" to_author_id="a64a52cc-3ee9-4a15-918b-099e18b43119"

8. Consuming events again

php bin/console messenger:consume events_async

9. Follower Counters Query

http --json http://127.0.0.1:8000/chapter7/author/a64a52cc-3ee9-4a15-918b-099e18b43119/followers-counter
http --json http://127.0.0.1:8000/chapter7/author/1fd7d739-2ad7-41a8-8c18-565603e3733f/followers-counter
http --json http://127.0.0.1:8000/chapter7/author/1da1366f-b066-4514-9b29-7346df41e371/followers-counter

Expected output

{
    "_meta": {
        "message_id": "0e9df870-894f-4d37-a140-4d598941fa4f"
    },
    "data": {
        "authorId": "a64a52cc-3ee9-4a15-918b-099e18b43119",
        "authorUsername": "bob",
        "numberOfFollowers": 1
    }
}

10. Posting Cheeps

http --json --body POST http://127.0.0.1:8000/chapter7/cheep cheep_id="28bc90bd-2dfb-4b71-962f-81f02b0b3149" author_id="a64a52cc-3ee9-4a15-918b-099e18b43119" message="Hello world, this is Bob"
http --json --body POST http://127.0.0.1:8000/chapter7/cheep cheep_id="04efc3af-59a3-4695-803f-d37166c3af56" author_id="1fd7d739-2ad7-41a8-8c18-565603e3733f" message="Hello world, this is Alice"
http --json --body POST http://127.0.0.1:8000/chapter7/cheep cheep_id="8a5539e6-3be2-4fa7-906e-179efcfca46b" author_id="1da1366f-b066-4514-9b29-7346df41e371" message="Hello world, this is Charlie"

11. Author Timeline

http --json --body http://127.0.0.1:8000/chapter7/author/a64a52cc-3ee9-4a15-918b-099e18b43119/timeline
http --json --body http://127.0.0.1:8000/chapter7/author/1fd7d739-2ad7-41a8-8c18-565603e3733f/timeline
http --json --body http://127.0.0.1:8000/chapter7/author/1da1366f-b066-4514-9b29-7346df41e371/timeline

cheeper-ddd-cqrs-example's Issues

Error when running make infrastructure