An AddPermissionMessage is used to request the addition of a permission to a database for an user.
A ListPermissionMessage is used to request the list of permission related to a specific user.
A ListPermissionsInfo is used to store the list of permissions assigned to a user
Trait that every message that belongs to permissions management operations has to extend.
A RemovePermissionMessage is used to request the removal of a permission to a database for an user.
PermissionManagementMessages are used to manage operations about user's permissions to access data.