問14
頻出度★★★
DFD の表記に関する記述として, 最も適切なものはどれか。
平成29年度 春期 ITパスポート試験 問14
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 14
Incorrectア
The description “it represents the transitions of a system’s states accompanying the passage of time and changes in situation” applies to a state transition diagram (state machine diagram). It focuses on states and the events that change them, so its purpose differs from DFD, which centers on the flow of data.
Incorrectイ
The description “it associates the entities handled by a system with one another to represent the structure of data” applies to an E-R diagram (Entity-Relationship Diagram). It models the static structure of data (entities and relationships), which is different from DFD that represents the flow of data through processes.
Incorrectウ
The description “it represents the attributes and operations of the elements that make up a system, and the relationships among the elements” applies to a class diagram (UML). It is a method for representing the structure and relationships of classes in object orientation, and does not apply to DFD, which depicts the flow of business data.
- エ
正解 DFD (Data Flow Diagram) is a method that represents a business or system by focusing on how data flows through it. Using four elements — the sources/sinks of data (external entities), processes, data stores, and the data flows (arrows) that connect them — it depicts which data passes through which process and where it is passed on. Therefore, choice エ, which reads “focusing on the flow of data, it represents the relationship between the flow of business data and the processing”, best fits the definition of DFD and is the correct answer.
ここがポイント
- DFD (Data Flow Diagram) focuses on “the flow of data” and uses four elements — external entities, processes, data stores, and data flows — to represent the relationship between the flow of business data and its processing.
- Distinguishing it from similar diagram methods: state transition diagram = transitions of states, E-R diagram = structure of data (entities and relationships), class diagram = attributes, operations, and relationships of classes. Tell them apart by their purpose.
用語