* Question
A simple DFD graphic description consists of the following four basic components, what are they?
* Answer
A simple Data Flow Diagram (DFD) consists of the following four basic components, which are essential to represent how information flows within a system:
1. Processes (Circles or Rounded Rectangles)
Description:
A process transforms incoming data flows into outgoing data flows. It represents an action or function performed on the data.
Example:
“Validate Order”
“Calculate Total”
Symbol:
Usually drawn as a circle, oval, or rounded rectangle, labeled with a verb-noun phrase (e.g., “Process Payment”).
2. Data Flows (Arrows)
Description:
A data flow shows the movement of data between processes, data stores, and external entities. It represents what data is being passed and in which direction.
Example:
“Customer Info”
“Order Details”
Symbol:
Drawn as a straight arrow, labeled with the name of the data (e.g., “Invoice Data”).
3. Data Stores (Open-Ended Rectangles)
Description:
A data store holds information for later use. It represents files, databases, or any repository from which a process can read or write data.
Example:
“Customer Database”
“Inventory File”
Symbol:
Drawn as an open-ended rectangle or two parallel lines.
4. External Entities (Squares or Rectangles)
Description:
Also known as terminators, these represent external sources or destinations of data that interact with the system, such as users, organizations, or external systems.
Example:
“Customer”
“Bank System”
Symbol:
Drawn as a rectangle or square, placed at the edge of the diagram.
Summary Table
Component | Symbol | Role | Example |
Process | Circle / Oval | Transforms input into output | “Verify Login” |
Data Flow | Arrow | Shows direction of data movement | “User Input” |
Data Store | Open-ended rectangle | Stores data | “User Records” |
External Entity | Rectangle | Source or sink of data | “Customer” |
These four components work together to provide a clear, structured view of system functionality and data movement, especially useful during system analysis and design phases.
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