Data Flow Diagrams Concepts

This video tutorial introduces Data Flow Diagrams (DFDs), explaining their purpose in illustrating data movement within systems. It covers common symbols and components used in DFDs, such as process boxes, external entities, and data stores. The tutorial provides examples of Level Zero and Level One DFDs, highlighting differences in detail and specificity. It concludes with rules for creating accurate DFDs and tips for interpreting them in exams.

What is the primary purpose of a Data Flow Diagram (DFD)?

• To list the hardware components of a system

• To display the user interface design

• To illustrate how data is used and moves around a system

• To show the physical layout of a system

Which symbol in a DFD represents a process?

• Diamond

• Circle

• Rectangle

• Arrow

What does an external entity in a DFD typically represent?

• A database

• A file

• A network

• A human or system providing or receiving data

In a DFD, what does a data store symbol typically look like?

• A rectangle with a missing edge

• A circle

• A triangle

• A diamond

What is the main difference between a Level Zero DFD and a Level One DFD?

• Level One DFDs are less detailed

• Level One DFDs provide a high-level overview

• Level Zero DFDs are more detailed

• Level Zero DFDs provide a high-level overview

In the backup system example, who initiates the backup request?

• The file manager

• The storage device

• The technician

• The database

What additional elements are included in a Level One DFD compared to a Level Zero DFD?

• More external entities

• Less detailed data flows

• Fewer process boxes

• More detailed process boxes

Which of the following is a rule for creating a Level One DFD?

• External entities do not need inputs or outputs

• Each process must have at least one input or output

• Data flows do not need to be labeled

• Data can flow in multiple directions

Why should data flow only in one direction in a Level One DFD?

• To reduce the number of arrows

• To make the diagram look simpler

• To clearly indicate the direction of data flow

• To avoid using too many symbols

What should every data flow connect to in a Level One DFD?

• A manager

• An external entity

• A process

• A data store