If you're looking to send data to clients outside of a normal request to a hub then I'd recommend having a static Concurrent Dictionary on your hub that manages your users and maps them to corresponding connection Id's.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.