Presuming that you're trying to script input into a menu-driven routine to generate data or perform some action, the best course of action would be to analyze the code of the legacy menu routine and see what it is calling to actually generate data or perform the action based on the menu input and have your endpoint call that code directly with the proper inputs from your REST endpoint, bypassing the need for the menu and any scripted input. 

I'm amazed at how little code is actually required to get a fully operational server application running! Nice work!

Perfect, that's exactly what I needed! Thanks!