What Depot Does
Let’s start by jotting down an outline specification for the Depot application. We’ll look at the high-level use cases and sketch out the flow through the web pages. We’ll also try working out what data the application needs (acknowledging that our initial guesses will likely be wrong).
A use case is simply a statement about how some entity uses a system. Consultants invent these kinds of phrases to label things we’ve known all along. (It’s a perversion of business life that fancy words always cost more than plain ones, even though the plain ones are more valuable.)
Depot’s use cases are simple (some would say tragically so). We start off by identifying two different roles or actors: the buyer and the seller.