Example: Writing a research paper.

Step 1: Draw Context Diagram

External Entities: Professor, Library

Context diagram establishes the boundary between the system and the external environment, i.e., shows scope and boundary.

Level 0 begins system description.

Step 2: decompose process - list activities involved, and then group those activities into three to ten major processes.


Step 3: Use major processes and external entities and data flows from context diagram to develop Level 0 DFD.

Level 0 DFD: Write Research Paper


Step 4: Analyze each process in Level 0 to derive Level 1 diagrams.

(In this example, the Level 1 diagram will consist of four diagrams: Level 1 Diagram 1, Level 1 Diagram 2, Level 1 Diagram 3, and Level 1 Diagram 4.)

Technique: Identify functions and what is needed to conduct functions.

example: What happens in Determine Paper Topic?

Remember that every flow in or out of Determine Paper Topic process on Level 0 must be shown in Level 1 Diagram 1: Determine Paper Topic.

Show boundary with dotted line.

Level 1 Diagram 1: Determine Paper Topic

example: What happens in Perform Research?

example: What happens in Prepare Draft?

example: What happens in Finalize Paper?