Level 1 Data Flow Diagram in draw.io (DFD Step by Step)
A level 1 data flow diagram opens up the system into its numbered processes and data stores. Learn how to turn on the data flow diagram shapes in the free draw.io web app, number each process, and label every flow with the data it carries, using an online shop.
Step by step
Inside the system
- DFD level 1. A context diagram shows the whole system as one bubble. A level one data flow diagram opens that bubble up into processes and data stores. Here's the one we'll build for our online shop.
- Blank diagram. Start a blank diagram in draw.io.
- DFD shapes. Click more shapes, tick data flow diagram, and click apply. The new shapes show up at the bottom of the panel.
Processes and flows
- External entity. Start with the customer. It sits outside our system, so it's an external entity. Drag in the plain box and name it.
- Numbered processes. Processes are the bubbles. At level one, give each one a number, so the next level down can refer to it. Process one, take order.
- Label with data. Hover over the customer and drag the blue arrow onto the bubble. Label the flow with the data it carries, a noun, not an action. Order.
Data stores
- Data stores. Data stores appear for the first time at level one. Drag in the open-ended box under the process. Store D one, orders.
- Label with data. Take order writes the order into the store. Connect them and label it. New order.
- Numbered processes. Process two, ship order. Put it on the left, under the customer.
- Label with data. Data can flow out of a store into a process. Connect orders to ship order. Order to ship. Shipping sends the customer a delivery note. Connect it up to the customer.
- Data stores. Take order also needs prices. Add a second store on the right. D two, products.
- Label with data. Connect the store to take order, and label it. Product price.
Check the rules
- Process in between. Look at the customer. It never touches a store directly. Every flow between an entity and a store, or two stores, goes through a process.
- The finished diagram. Click away to see the finished level one diagram.
Recap
- The rules. So, number every process, label every flow with the data it carries, and always put a process between entities and stores. Every flow on your context diagram must show up here too.
