What is the best protocol for Real-Time Communication

Dear All,

I have been thinking about what is the best way to establish a communication where the real-time and response-time are important including the scaleability of the system .

TCP can be a bit tricky and RTT’s can be a problem. UDP is fast but packet loss can be a problem. I havent research CoAP very-well. What do you think its current importance in Riot enabling fast response time and sustaining real-time constraints?

Thanks.