Since the hub is the central point of contact, it is also the primary target for attacks.
Build a mechanism where the hub attempts to re-send failed requests 3 times before giving up. How To Make A Serverside Hub Part 2/2
Run multiple instances of your hub behind a Load Balancer . Since the hub is the central point of
Use Socket.io (Node.js) or SignalR (.NET). This creates a "persistent pipe" between the hub and the users. How To Make A Serverside Hub Part 2/2
Every request passing through the hub must carry a JSON Web Token (JWT). The hub should verify this token before passing the request to internal services.