How difficult is it to develop ePOS (Point of Sale) System for restaurant?

Is it possible for me who know nothing about ePOS to develop an ePOS application in approximately a month? Which language is the most suitable to develop this kind of application? I'm planning on writing the program using Java. I have read about Java API called JavaPOS but there seems to be limited resource about it on the internet. Can I use basic Java language to develop my application? This ePOS application will be use with touch screen panel and will be integrated with wireless technology (PDA for taking orders from customer). Thank you.