I was looking for something like this for a project that involve IoT device and need near real time feedback. One thing that isn't clear to me is what should be used to communicate between the devices and servers? Having no experience with it (and having background in Node.js), websockets sounded like a way to go at first but I didn't see it mentioned much in that context, on the other hand I heard about few projects…
If it's okay to lose an update or two every now and then, you can send individual UDP packets with something like JSON or MessagePack in them. Otherwise use a raw TCP socket. No need for a framework and HTTP just to communicate.
For bigger systems, RabbitMQ is pretty nice.