How to Draw a Context Diagram (Level 0 DFD) in draw.io
A context diagram, also called a level 0 data flow diagram, shows the whole system as one bubble and the people and systems that trade data with it. Learn to draw one in the free draw.io web app, with every flow labelled with the data it carries, using an online shop.
Step by step
The big picture
- Context diagram. A context diagram, or level zero DFD, shows your whole system as one bubble, plus everyone who trades data with it. It's the quickest way to agree on scope. Here's the one we'll build for an online shop.
- Blank diagram. Start a blank diagram in draw.io.
One system
- One process. The whole system is one process, so drag a single ellipse into the middle of the page. Name it after the system. Online shop system.
External entities
- External entities. External entities are the people or systems outside it. They're plain rectangles. Put the customer on the left.
- Label with data. Hover over the customer and drag the blue arrow onto the system. Label the flow with the data it carries, a noun. Order.
- External entities. The warehouse sits outside the system too. Put it on the right.
- Label with data. Data goes out of the system as well. Drag from the system to the warehouse, and label it. Pick list.
- External entities. Next, the supplier. Put it above the system.
- Label with data. The supplier sends us its prices. Connect it down to the system. Price list.
- External entities. And the shop manager goes below the system.
- Label with data. The manager gets a report every week. Connect the system down to the manager. Sales report.
Check the rules
- No data stores. Look at the middle. There are no data stores and no inner steps at level zero. Everything inside the system stays hidden until the level one diagram.
- The finished diagram. Click away to see the finished context diagram.
Recap
- The rules. So, one process for the whole system, external entities around it, and every flow labelled with the data it carries. No data stores at level zero.
