The first service is responsible for the registration of users. It has to contain methods to add, update, or delete users. We can cover all needs with the standard REST approach. We will use a combination of methods and paths to provide this user registration functionality:

• POST request to /user/ creates a new user and returns its id
• GET request to /user/id  returns information related to a user with id
• PUT request to /user/id  applies changes to a user with id
• DELETE request to /user/id  removes a user with id

This service can use the E-mail notifications microservice and call its methods to notify the user about registration.