We're implementing a book store. We should keep track of the following entities: Books, Customers, Purchases and Emails. There are a few requirements that we need to cover:

• When a book gets added/updated with a price of 0. All customers will automatically purchase this book for that price.
• When a customer signs up, all books with a price of 0 will automatically be purchased by that customer.
• When a customer signs up, we'll sent a welcome email to that customer automatically.
• When the customer makes a purchase, we'll send a purchase confirmation email to that customer automatically.
• When a customer signs up, we'll automatically assign Customer.SignupDate to the current date.
• When an email gets queued we'll automatically set the QueuedDate to now
• When an email gets sent out we'll automatically set the SentDate to now

There are 2 variants of the same sample application: BookStoreSampleApp.Simple and BookStoreSampleApp.Triggered. The former covers a traditional implementation of the given scenario wheras the latter embraced EntityFrameworkCore.Triggered to drive its business logic