Mastodawn

Julia Evans Jun 19, 2024

when I asked people to explain how UDP works I got a lot of answers to the effect of "it's spray and pray"

but I'm having trouble thinking of examples of UDP-based protocols that actually work in a "spray and pray" way —

* DNS is "send 1 packet, retry if you don't get a reply”
* QUIC is a sophisticated system for streaming data over UDP
* I'd guess that video protocols correct for packet loss
* maybe statsd is a "spray and pray” system?

(please do not reply to this explaining how UDP works)

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Paul Khuong

@b0rk Syslog over UDP does that; I assume other stats/logging systems make the same trade off re simplicity and bounded work in the client VS delivery guarantees.

Otherwise, I think I've only seen un-acked sends coupled with erasure coding, for latency sensitive payloads where getting the data multiple RTTs late is useless. So sure, some amount of prayer, but only after putting extra work to let receivers cope with a couple lost packets.