🟡 Medium Example: Ordering Food Online

Now let us look at a slightly more complex system with multiple processes and data stores.

Scenario: A customer orders food through an app. The system processes the order, checks the menu, stores the order, and sends confirmation back to the customer.

📖 What This Diagram Shows

This DFD has: 2 external entities (Customer, Restaurant), 2 processes (Place order, Process payment), 2 data stores (Menu, Orders), and 7 data flows (the labelled arrows). Notice how every arrow is labelled and every data flow goes through a process — data never flows directly between external entities.