I want a basic server to multiple clients communication, in which there will be a message exchange protocol (obviously based on the FSM principle).
It is about a simple quiz game, where the server has previously downloaded a database (based on OMDB Api). Keeping that in mind, the server randomly chooses the questions that will be on the current game, based on the criteria that the user has previously specified (imdb rating 7.1-10). There is no need for internet connection (for both server and client), but only for a wifi (in order for the server to create a tethered connection, where the clients could connect to). The only case that internet may be used for, is when the server wants to perform a database update.
Some other requirements:
the server should be very light (and should also handle easily at least 10 clients)
the protocol to be created should be open and well defined, in order to be easily migrated
So, keeping that in mind, I thought raising a topic here, as I have read about lots of possible technologies, but I firstly want to get a more sophisticated/expert opinion, as I only have the basic knowledge of Android and I do not know which option would fit the fore-mentioned requirements, at most.