Hi, I'm rather proficient in creating standalone desktop based java programs.... What i know nothing about is networking multiple programs together..

I've been tasked with creating a program can be installed (or copied) to multiple computers (Slave computers), and have these access the one Database or File on another computer (Master computer).

The program is basically a customer & product & sales database for a mall jewelery shop.
The slave computers would be for entering sales and customer data.
the master computer is in the bosses office and will have a couple advanced, statistics & sales details.
The computer are internet connected, but also connected via LAN.

what I'd like to know is...
1. Whats the best method to achieve this? - Online Database? Shared File? etc.
2. Wheres the best place to learn about this topic? (specifically, how to link the Slave -> Master Computer)

Thanks in advance