Type the pattern template, filled in for a real BorrowBox design decision. Five fields, and the fifth is not optional.

Answer

Pattern: One-Time Token Context: unattended pickup, no staff at the depot Problem: prove the collector is the right member Forces: must expire | must work with the bank offline | must not be guessable from a previous token Solution: issue a signed short-lived token, validate at the edge Consequences: clock skew becomes a failure mode; revocation is slow

A pattern is not a solution, it is a rule over a context. Typing the template makes that structural: the forces are what turn a good idea into a pattern, because they are the reasons the obvious solution does not work here, and the consequences are the honest price. A candidate who writes solution-only has described a technique and will be marked as such.

Pressman 9e ch14