Book Image

Domain-Driven Design in PHP

By : Keyvan Akbary, Carlos Buenosvinos, Christian Soronellas
Book Image

Domain-Driven Design in PHP

By: Keyvan Akbary, Carlos Buenosvinos, Christian Soronellas

Overview of this book

Domain-Driven Design (DDD) has arrived in the PHP community, but for all the talk, there is very little real code. Without being in a training session and with no PHP real examples, learning DDD can be challenging. This book changes all that. It details how to implement tactical DDD patterns and gives full examples of topics such as integrating Bounded Contexts with REST, and DDD messaging strategies. In this book, the authors show you, with tons of details and examples, how to properly design Entities, Value Objects, Services, Domain Events, Aggregates, Factories, Repositories, Services, and Application Services with PHP. They show how to apply Hexagonal Architecture within your application whether you use an open source framework or your own.
Table of Contents (24 chapters)
Title Page
Credits
Foreword
About the Authors
Acknowledgments
www.PacktPub.com
Customer Feedback
Dedication
Preface
14
Bibliography
15
The End

Publishing Events from the Domain Model


Domain Events should be published when the fact they represent occurs. For instance, when a new user has been registered, a new UserRegistered Event should be published.

Following the newspaper metaphor:

  • Modeling a Domain Event is like writing a news article
  • Publishing a Domain Event is like printing the article in the paper
  • Spreading a Domain Event is like delivering the newspaper so everyone can read the article

The recommended approach for publishing Domain Events is to use a simple Listener-Observer pattern to implement a DomainEventPublisher.

Publishing a Domain Event from an Entity

Continuing with the example of a new user who has been registered in our application, let's see how the corresponding Domain Event can be published:

class User
{
    protected $userId;
    protected $email ;
    protected $password;

    public function __construct(UserId $userId, $email, $password)
    {
        $this->setUserId($userId);
        $this->setEmail($email...