I've been working on a hotspot backend system for the last three months and its been in production for almost two months now. Since it has been working so well they want me to adapt it for use in hotels.
The currently installed hotels use a Colubris CN-3200 or a MSC-3200 Access Controller. These units can interact with a backend service in a number of ways. Currently they use a "NOC" method where they simply pass everything to a remote server and then the remote server authenticates the user so the user never actually uses anything on the access controller itself.
The method which I use is that the access controller makes the initial connection and then passes the user through to a remote server. The remote server then passes the user back to the access controller which then authenticates against the remote server. This might sound like more effort/waste but it offers far more flexibility - for example I can have a remote web server and a separate authentication server. This is identical to how the Mikrotik RouterOS systems work.
Given this tweaking my application isn't too difficult. Just a case of either setting or detecting which access controller is in use and make the necessary adjustments to the templates and database. I should have this done in a few weeks since I have to revamp some bits to optimise the process.
It would be interesting to try some more access controller brands and see if I can achieve some across market compatibility. Although I'm happy with the RouterOS and Colubris units - together they cover pretty much every purpose I can think of.