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Hard real time udp communications is quite appealing. WebRTC and Object Real Time Communications (ORTC) claim to provide real time communications with udp. Does this mean "close enough to wall clock time to not notice" or are they designed with hard real time determinism requirements?

Are there any tests showing deterministic udp communications?

How real-time are these communication methods?

Marc Compere
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Definitely not "close enough to wall clock time to not notice"

100 ms latency at best, 300-800 ms in average, no guarantees and no mission-critical grade reliability. You should not use any IP-based technologies for for mission-critical applications. IP (internet protocol) was not designed for that.

Consumer-grade toy, nothing more. If it fails or freezes, you refresh your browser or come back in 10 minutes and try again. You would not use these technologies for military applications, remote control of medical machine conducting some procedure, and anything else that requires ultra-high reliability.

However, good enough for video conferencing and surveillance over web, where nobody dies if the application hangs 2% of times, and 500 ms latency is acceptable.

Try https://appr.tc/ for testing.

user1390208
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  • I have a hard time believing 100ms latency in best case scenario. udp can provide round trip messaging typically under 10ms and often around 2 or 3 ms. If the test app or case you're referring to uses video there must be some processing involved. I'm interested in simple messaging more than images or audio. The 'real time' claims are appealing. I've seen no test results with latency as a function of payload size – Marc Compere May 24 '20 at 00:58
  • For UDP-based messaging in the browser, you can go with WebRTC-UDP data channel, and yes, then the latency can be better than 100ms. Can be! But no reliability! Your UDP packets can be lost at times, so sometimes your messages will not arrive at all. Latency is not necessarily a function of payload size. UDP datagram of 10 bytes will take the same to arrive as UDP datagram of 50 bytes. WebRTC-TCP data channel, or plain websocket helps to solve reliability problem, but potentially increases the latency. – user1390208 May 24 '20 at 03:02