Of the various internet .+P, NTP is one I never learned about as a student, so now I'm looking at its web page [1] by its creator David L. Mills (1938-2024). I've found one video of him giving a retrospective of his extensive internet work; he talks about NTP at 34:51 [2] and later at 56:26 [3].
[1] https://www.eecis.udel.edu/~mills/ntp.html
HN discussion shortly after Dave Mills died, early in 2024: https://news.ycombinator.com/item?id=39051246
Amazingly, The New Yorker wrote an article about it: https://www.newyorker.com/tech/annals-of-technology/the-thor...
In [3] he mentions that one can use NTP to observe frequency deviations and use it as an early warning system for fire and AC failure. That really intrigues me. Can you actually? Has this ever been implemented?
Oscillators of all kinds are temperature dependent.
That's why the most stable ones are insulated and ovenized[1].
So an AC failure which would lead to higher room temperatures would lead to stronger or more frequent correction by the NTP client, as the local oscillator would drift more.
Not sure about the fire case though. I mean the same applies there but I'm not imaginative enough to think of a realistic scenario where NTP would be useful for averting a fire.
[1]: https://blog.bliley.com/anatomy-of-an-ocxo-oven-controlled-c...
I knew of some experiments in this space back in the late 1980s or early 1990s - but it was specifically with DECstation hardware that had terrible clocks (not used for alerting, just "this graphs nicely against temperature".) https://groups.csail.mit.edu/ana/Publications/PubPDFs/Greg.T... (PDF) 4.2.1 does talk about explaining local clock frequency changes with office temperature changes (because they overwhelm a clock-aging model) but it doesn't have graphs so perhaps they weren't clear enough to include (or just not relevant enough to Time Surveying.)
What do you mean by +P?
Presumably, .+P is regex referring too all the acronyms ending with P, that is Protocol. SMTP, HTTP, FTP, IMAP, XMPP…
Looks like .+P is just a regex way of saying any set of characters / protocol ending in P.
Nothing, as they said .+P (note the dot)