I’m still working on Vrui’s second-generation collaboration / tele-presence infrastructure (which is coming along nicely, thankyouverymuch), and I also recently started working with another group of researchers who are trying to achieve similar goals, but have some issues with their own home-grown network system, which is based on Open Sound Control (OSC). I did some background research on OSC this morning, and ran into several instances of an old pet peeve of mine: the relative performance of UDP vs TCP. Actually, I was trying to find out whether OSC communicates over UDP or TCP, and whether there is a way to choose between those at run-time, but most sources that turned up were about performance (it turns out OSC simply doesn’t do TCP).

Here are some quotes from one article I found: “I was initially hoping to use UDP because latency is important…” “I haven’t been able to fully test using TCP yet, but I’m hopeful that the trade-off in latency won’t be too bad.”

Here are quotes from another article: “UDP has it’s [sic] uses. It’s relatively fast (compared with TCP/IP).” “TCP/IP would be a poor substitute [for UDP], with it’s [sic] latency and error-checking and resend-on-fail…” “[UDP] can be broadcast across an entire network easily.” “Repeat that for multiple players sharing a game, and you’ve got a pretty slow, unresponsive game. Compared to TCP/IP then UDP is fast.” “For UDP’s strengths as a high-volume, high-speed transport layer…” “Sending data via TCP/IP has an ‘overhead’ but at least you know your data has reached its destination.” “… if the response time [over TCP] was as much as a few hundred milliseconds, the end result would be no different!”