05 Dec PORTFOLIO ASSIGNMENT This assignment will serve as the “Portfolio Assignment”

PORTFOLIO ASSIGNMENT

This assignment will serve as the “Portfolio Assignment” for this course. A portfolio assignment is an applied assignment that showcases your ability to apply what you learned in this class. You are encouraged to create a free DU portfolioLinks to an external site.  in which you can store evidence of what you learned (such as papers, projects, and key course assignments) as you move throughout your coursework at University College. You have the ability to share the portfolio with potential employers or colleagues. Keeping a portfolio will allow you to reflect on, provide context for, and continue to hone your work samples as you build knowledge and skills throughout your time at DU.

PURPOSE OF ASSIGNMENT

This assignment will bring together the learning from the previous assignments. Collect together all your work thus far and put it into a coherent unified high-level design for the system. You are welcome to use previous assignments verbatim where appropriate although you should be sure to incorporate the feedback on them.

As a reminder, here’s the original description of the system we’re creating:

Have you ever stopped to consider what happens when you’re shopping online? In between entering your credit card information and the money getting charged to your account is a very complex set of interactions. During this class, we will explore a simplified payment processing system that does exactly this. We’ll create a design for it and provide sample implementations for some of the components. 

Let’s take a look at some of the details of a payment processing system. 

FORMS OF PAYMENT

To keep this simple we’ll assume that we only accept credit cards for payment.

FRONTEND

The happy shopper needs some way to enter their payment details.

ONLINE STORE

The storefront needs an interface to the processing system where they can enter the shoppers’ details, get confirmation that they can charge the card, and collect the money afterwards.

CREDIT CARD PAYMENTS

Paying by credit card, whether online or in a physical shop, follows a two-step process. 

When your card is first run, it performs an “authorization”. This authorization takes the credit card details and the amount requested and sends them to the credit card company. The company then looks up the card and verifies whether or not the payment will succeed. A status code (OK or some kind of error code) is returned, along with an authorization code if the status is OK. 

Later on (e.g. once an hour, once a day) all of these authorizations are collected up into a single batch and sent as “payment requests” to the credit card company. A payment request contains the same information as the initial authorization along with the authorization code that was returned. The credit card company will respond with statuses for each payment request and all the money for those requests that succeeded is transferred into the store’s bank account.

PAYMENT PROCESSING SYSTEM

The system needs to implement credit card processing as described above. 

CREDIT CARD COMPANY

We shall assume we use a single credit card processor and that processor provides us with an interface for performing authorizations in real time