I am missing a fundamental idea on how JavaPOS works, could anyone enlighten me?

A new employer wants me to create a mobile Java App that is of the "ordering food at a restaurant" variety using JavaPOS. I can imagine making the UI on the phone, but what does it communicate to? What path does my app make in getting to the specific restaurants device hardware and inputting an order on its own?

sounds more like homework than for a job?

anyways... you would need or already have some central Database server setup, that stores your menu items, etc. You would have your device communicate with that database server either over local lan (intranet) or wan (internet), and query for available food items. then display them somehow on the screen for the server to select from, then some kind of submit function to send the selected items back to a new table in the database so that the order can be filled. of course when you submit the order you must have some mechanism monitor the table for new submissions, then print out an order ticket for the kitchen, etc.

anyways... thats the basic idea i think.