I am new to the formal idea of UML diagrams, but I have drawn and read system type diagrams for years. I wish to set a very simple exercise for the analysis stage of a project. I am considering the operation of a checkout till with a built-in scanner and weighing device. I can capture the interaction of the checkout operator and the customer with the till with a Use Case diagram. However, what is the optimum type of diagram to show the high-level internal operation of the till such as “scan and interpret barcode”, “look up code” and output item name and price on display, “read payment card” etc.?



The behaviors of a system are usually captured in UML with use case (requirements), sequence diagrams (interaction scenario between several classes), or activity diagrams (logical internal flow).

The activity diagram would best be used to model your narrative.

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