CUSTOMER
1.
get
valid
customer
selection
2
.
look-up
product
price
3.
get
payment
4.
dispense
product
5.
dispense
change
PRODUCT
TABLE
CUSTOMER
CUSTOMER
selection
valid
selection
returned
change
product
and price
object
product
selected
product
returned
object
PRICE
TABLE
PRODUCT
TABLE
product
requested
T
T
T
T
product
dispensed
no
product
product
OK
coin
return
requested
coins
OK
0.
vend
control
program
change
dispensed
