Progress Report 2

Progress update 2

I'm now well into the process of building the backend for the cart slice.

The first order of business was to actually figure out exactly what each layer would have to do; I had the vague understanding that the Control layer would link the frontend to the application layer with an API, the app layer would activate the correct service in the service layer, and this would evaluate business logic, make calculations etc, before activating the data layer to write an order to the database.

Top to bottom:

• The API performs validation on the order it receives to make sure it's not empty. If it fails the function ends and an error message is returned to the browser. It then creates a variable which stores the output of the createOrder function, which is the name of the app layer function, passing the order object down to it. The API then carries out an outbound validation to check if the returning object is empty (as in if operations down the chain failed). If that passes there's a successful response passed back.
• The app layer uses the createOrder function which is very simple and activates createOrderService, passing order down to the service layer.
• This is where I am now. The service layer is the most complex and includes four main steps:
  • Compare orders data to database; extract product/customer data.
  • Execute business logic.
  • Create an order.
  • Activate database operations.
• When I realised I will need two sets of database operations, I decided to start writing the first set before finishing the service function. That makes more sense to me. I also believe at this point I should actually build the place order button in the frontend and connect it to the API so I can start to look at the data as it is passed down.