Illustration of a simple hexagon one user (left) port and one db (right) port.
It simply calculates the formula:
result = input * rate
e.g. result = 100 * 1.1 = 110
The user port is connected to either the web or to a test harness, with or without the server adapter, The db port looks up the rate in a database, either in-the-code db, or from a file.
The startup decides how the wiring goes.
Run test_smaller_web_hexagon to run the tests.
Run rackup config.ru
to get the web UI on port 9292