問9
頻出度★★★
DFD において，データフローや処理（機能）以外に記述されるものだけを全て挙げたものはどれか。 a データの処理に要する時間 b データの蓄積場所 c データの発生源や出力先
令和元年度 秋期 ITパスポート試験 問9
ストラテジ系システム戦略 › 業務プロセス
This question's explanation and your answers so far.
解説
問 9
Incorrectア
The pair 'a, b'. Item b, 'the location where data is stored' (the data store), does correctly apply, but this pair wrongly includes a, 'the time required to process the data', and it also omits the correct element c, 'the source and the destination of the data' (the source / sink). A DFD depicts the flow and processing of data and does not describe temporal factors such as processing time or ordering, so a pair that contains a is wrong.
Incorrectイ
The set 'a, b, c'. Items b (the data store) and c (the source / sink) are correct elements, but including a, 'the time required to process the data', as well is the mistake. A DFD does not express time, timing, or control flow, so a is not one of its building blocks.
- ウ
正解 A DFD (data flow diagram) has four building blocks: the data flow (an arrow), the process (processing / function), the data store (the location where data is stored), and the source / sink (external entity: where data originates or is sent to). The question asks for the elements other than data flows and processes (functions), so the ones that qualify are b, 'the location where data is stored' (the data store), and c, 'the source and the destination of the data' (the source / sink) — two items in all. Therefore ウ, which lists b and c, is the correct answer.
Incorrectエ
Only 'c'. Item c, 'the source and the destination of the data' (the source / sink), is a correct element, but by itself it is not enough. Item b, 'the location where data is stored' (the data store), is likewise a DFD building block other than data flows and processes, so this choice, which lists only c, is incomplete and therefore wrong.
ここがポイント
- The four building blocks of a DFD: the data flow, the process (processing / function), the data store (the location where data is stored), and the source / sink (external entity = where data originates or is sent to).
- A DFD is a diagram that represents 'the flow and processing of data'; it does not express temporal factors such as processing time, ordering, or control.
用語