[iapi]

I would suggest any programming that you are comfortable with and use a NoSQL Database.

You can use Erlang because is not only about scalability but mostly about:

reliability

soft real-time characteristics (enabled by soft real-time GC which is possible because immutability [no cycles] and share nothing and so)

performance in concurrent tasks (cheap task switch, cheap process spawn, actors model, ...)

scalability - debatable in current state , but rapidly evolving