What you should be able to do
- Identify entities, processes, stores and flows.
- Check balancing between levels.
- Avoid illegal direct flows.
02 / REQUIREMENT ENGINEERING AND ANALYSIS MODELING / L11
Data Flow Diagrams: Level 0 and Level 1
A DFD follows data, not control flow. Level 1 must preserve the external inputs and outputs of the process it decomposes.
What data enters, changes, is stored and leaves the system?
Terms to use precisely
Common mistakes
- Drawing UI buttons or database commands as data flows.
- Connecting an external entity directly to a data store.
Follow data, not screens or clicks.
Connect the entities, process and store. The lab blocks invalid direct flows.
DRAWN FLOWS
Add a flow to begin.
For the Level 0 check, show student input, student output and the process reading diagram content.
CHECKED LEARNING LINKS
Watch the part that solves the gap.
Each link is matched to this lesson. Start with a quick video when available. Open the full lecture when you need the academic explanation.
WATCH FIRSTfull lecture
Lecture 24: Basics of Data Flow Diagrams
Learn entities, processes, stores, flows and functional decomposition.
GO DEEPERworked example
Data Flow Diagram Level 0 and Level 1 Sample
Watch a context-level model decomposed into a lower-level DFD. Note the title correction stated by the author.