IPA IP 2020 Question 11
A question IPA Japan published in 令和2年度 10月 ITパスポート試験 公開問題 問11, translated into English. ITPEC is based on the same exams.
Same question on ITPEC: Oct 2022 Q95
When a guest arrives at a certain restaurant, their name is registered in a visitor list. When the guest is allocated a seat, both the guest list and seating availability are referenced. Which of the following is the most appropriate DFD to represent this series of actions?
Explanation
Reception writes to Guest list; Show to seat reads Guest list and Seating availability — the DFD in (d).
In a DFD, an arrow from a process into a data store means the process writes to it, and an arrow from a store into a process means the process reads it. The story gives three flows:
- •The guest's name is registered in the visitor list: Reception → Guest list
- •Seating refers to the guest list: Guest list → Show to seat
- •Seating refers to seating availability: Seating availability → Show to seat
Only (d) draws exactly these three.
Answer (d)
Why not others:
- •(a) — Reception reads the Guest list instead of registering in it, and Show to seat writes to Seating availability instead of referring to it
- •(b) — Reception writes to Seating availability, Show to seat sends data back to Reception, and nobody registers the guest in the Guest list
- •(c) — Reception registers the guest but also writes to Seating availability, and Show to seat reads neither store; it only receives a flow from Reception
Key rule: Read the arrow direction at every data store: into the store is registering or updating, out of the store is referring to it.
System Development Technology · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.