[Standards-JIG] proto-JEP: Smart Presence Distribution

Carlo v. Loesch CvL at mail.symlynX.com
Wed May 17 19:29:22 UTC 2006


Jean-Louis Seguineau typeth:
| Sounds awfully like a fairy tale, isn't it ;) Once upon a time AOL published
| statistics on the subject that are not in agreement with this ratio. But
| maybe AOL is not relevant, they only have a few million concurrent users
| online at the same time... That said the messages were 3 to 1 over presence

yes this information is VERY relevant. this tells you what kind of ratio
jabber SHOULD have, because aol has no distribution to handle at all, it
doesn't have any retransmission overhead at all.

what i was talking about isn't the amount of times people change their
away status. i was talking about the amount of presence stanzas traveling
S2S, which is a lot higher, because every status change is transmitted
n times. without any optimization, the overhead is big. really big.

with our JEP the overhead is reduced. it still isn't topologically
optimized, that's the job for multicast, but even just sending a presence
update to each server once instead of n times makes quite a difference.

i should probably explain "topologically optimized" and "multicast":
you're in france or quebec or antigues, i don't know, but you have a
dozen friends in say argentina. in an ideal world your presence info
would only travel to argentina once, then redistribute on location.
we probably won't make multicast THAT smart, but it gives you an idea
where we are heading to.

yes multicast involves more trust on your friends' servers, but it's
the only way jabber can scale to surpass the big proprietary services.
why? because multicast stops the proliferation of overhead, which is
the problem.

| changes. If you want to demonstrate gains, you usually do sampling before
| and after, then compare (basic experimental approach). You do the whole
| process. You do not want to outsource your demonstration either, do you? 

i don't mind outsourcing the tests to you. i trust your results will
show the obvious and inevitable, unless you have an interest in not
improving jabber.

| What's the all point if the reduction is not important?

the reduction happens anyway, you can't go wrong.
the difference is only how much the reduction is.

| Nope. I'm the one building the servers others are using to provide big

excellent! then you can look up the figures that show how much
presence overhead is currently happening in interserver communications
of jabber! please do!




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