問31
頻出度★★★
業務をモデル化する際のモデリング手法の適切な組合せはどれか。
業務プロセスモデル データモデル DFD E-R 図 業務プロセスモデル データモデル DFD PERT 業務プロセスモデル データモデル E-R 図 DFD 業務プロセスモデル データモデル E-R 図 PERT
平成22年度 秋期 ITパスポート試験 問31
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 31
- ア
正解 The correct answer is ア. The two columns of the table ask about models from two different viewpoints. The left column, the business process model, is a model that shows what processing is done in the business and where data flows from and to, and its representative technique is the DFD (Data Flow Diagram). A DFD diagrams the flow of business operations using the symbols for data flow, process, data store, and external entity (source/sink). The right column, the data model, is a model that shows the structure of the data itself handled in the business, that is, what groups of data (entities) exist and how they are related, and its representative technique is the E-R Diagram (Entity-Relationship Diagram). An E-R Diagram uses entities and relationships to express, for example, the correspondence between “customer” and “order”. Therefore ア, the combination of business process model = DFD and data model = E-R Diagram, is appropriate. It is useful to memorize them as a pair: flow (process) is the DFD, structure (data) is the E-R Diagram.
Incorrectイ
The left column, business process model = DFD, is correct, but the right column, data model = PERT, is wrong. PERT (a PERT chart, also called an arrow diagram) shows the sequence of activities and the days they require using arrows and nodes, and is a project schedule management technique used to find the overall duration and the critical path. What it expresses is the order and schedule of activities, not the entities and relationships of data, so it cannot serve as a data modeling technique.
Incorrectウ
The techniques used, DFD and E-R Diagram, are the correct ones, but the left and right columns are swapped. An E-R Diagram expresses data structure with entities and relationships, so it is a technique on the data model side, while a DFD expresses the flow of data and the processing, so it is a technique on the business process model side. This option applies their roles the other way around, so it is wrong. This swap is the biggest trap in this question.
Incorrectエ
Both columns are wrong. An E-R Diagram is a data modeling technique, not a business process modeling technique, and PERT is a technique for schedule planning and process control, not a data modeling technique. This option also does not contain a single technique for expressing the flow of a business process (DFD), which is another reason the combination does not hold.
ここがポイント
- Business modeling is done from two viewpoints: process and data. The representative technique for the business process model (processing and the flow of data) is the DFD, and the representative technique for the data model (the structure formed by data entities and their relationships) is the E-R Diagram.
- A DFD expresses the flow of business operations with four symbols, namely data flow, process, data store, and external entity, while an E-R Diagram expresses data structure with entities and relationships. A PERT chart, also called an arrow diagram, is a schedule management technique (for calculating the critical path), so note that the domain it models is different from the other two.
用語