Domain Event How to get additional data?

Question

I'm building a ecommerce system by using DDD. In this system I have two bounded contexts: Identity & Access and Sales.

Customers can register themselves by filling in a form with their name, email and password. Then in the Sales context, I register a customer with:

$customer = new Customer($request->name, $request->email);
$this->customers->add($customer);

The Customer aggregate raises an CustomerWasRegistered event.

The Identity & Access context reacts on this event and creates a SystemUser aggregate for that customer:

$user = new SystemUser($email, $password);
$this->users->add($user);

My question: because the Customer aggregate doesn't know about a password (and neither the CustomerWasRegistered event). How can I get this password from the request to the Identity & Access context?

Answer 1

I see two solutions here:

1. If you really want to have a domain policy in I&A that will create a user after receiving "CustomerWasCreated" event, you might not want to ask new customers for password, instead you will send a link to activate their account and enter new password after the user (inactive) is created. This strategy is used very often but they will not be able to login before the process is completed.
2. What I would do - delegate this work to a process manager that will orchestrate the work between two BCs. The PC will know the password and will send an appropriate commands that contain necessary details.

In both cases you avoid sending password to the Sales BC.