I have a neighbor who sells ice cream. He owns several kiosks in various towns around the country. Two years ago we talked and he asked how hard would be to develop a simple POS (Point Of Sale) for him. He was very unsatisfied with his solution. He had a general cash register from which he had to download all transactions every day otherwise they would disappear. It had functionality he did not need but also lacked some functionality he needed. And it was expensive.
I worked for Radiant Systems so I know a thing or two about POS systems. This one is very simple. All it has to do is to send transactions to the server. The items and prices are fixed during the year which means there is no inventory management. The only changing variables are cashiers but their management is simple - we need to track just name, pin and kiosk where the cashier work. Reporting consists of one report with sold items and shift durations. Overall, quite simple functionality, right?
Then I started thinking about the server requirements which is a grey area for me. I don't know enough about it, especially about operations. I played with Node in Azure VM a little bit but I was not sure enough. The project went to sleep at the end of the year 2012…
To be resumed a year later. My neighbor was more angry about the cash registers. And there was a new feature in Azure - the Mobile Services. I don't need to deal with the server details any more. Exactly what I wanted. So in the autumn 2013, we agreed on an attempt to implement it and I started to work on a proof of concept.
Following the KISS principle, the initial design was as follows:
- Android tablet in each kiosk connected to the Internet via 3G modem
- HTML SPA (Single Page Application) as client POS application running in the browser on the tablet
I prototyped an initial solution during the rest of the year 2013. Three screens (sign in, cash box, report), all in one big awful HTML page. But that is what prototypes are for - to see whether it can work, then throw it away and do it properly. Here is the main screen from the prototype:
We tested it on a tablet and it looked good - a green light for my little, fun, real, side project. I had three months to properly develop it during my spare time. Yes, it was optimistic :-)