If we want to run the discount calculation when a user clicks a button on the customer’s browser screen, the most straightforward way to accomplish this is to put the calculation logic right in the browser screen controller.

See the Calculate discount button in the demo application and the screen controller implementation: CustomerBrowse.java. Please keep in mind that the provided calculation process is not optimal and see more options in the Loading and Saving Data section.

This approach is acceptable if the logic is invoked from a single point and it is not too complex to fit into a couple of short methods.