Example: Self-Service machine
The main function of self-service machine is to allow a customer to buy a product(s) from
the machine (candy, chocolate, juice...). Every user that you asked for a set of scenarios
happening during usage of machine, can tell you that main use case can be labeled as "Buy
a product". Let's examine every possible scenario in this use case.
The "Buy a product" use case
The actor in this use case is a customer. This customer wants to buy some of the products
offered by the self-service machine. First of all he/she inserts money into the machine, selects
one or more products, and machine presents a selected product(s) to the customer. Use case diagram
for this scenario can be represented as:
