On Fri Apr 30 17:26:16 2010, Bob Wyman wrote:
Please do not regress to the old, now largely deprecated, light
pinging/notification model. That stuff works great in small systems
or in
prototype demonstrations, but it is a real mistake for any system
that
expects to experience successful growth.
I agree that if you have a case where information is demanded on
every notification, then yes, you will end up with a thundering herd
problem as the majority of subscribers stampede to get the same
additional information they seek at once.
But please, credit me with at least half a brain cell.
XEP-0115 and PEP already interact such that notifications contain the
information that has changed, and that is interesting to the client.
So, in this instance, instead of sending out full profile, geoloc,
full name, profile statement, and favourite colour information with
every notice, then you'd send such information out individually when
it itself had changed - if clients expressed an interest in it. In
other words, you rely on the clients maintaining state. If the state
is, for some reason, lost or unavailable, then in this case an
explicit request is indeed made, but this is triggered not by a
notification, but by client-specific circumstances, and therefore
does not yield a thundering herd.
The XMPP community is already deploying such mechanisms out in the
real world on substantial scale, and it works just fine, by the way.
Dave.
--
Dave Cridland - mailto:[email protected] - xmpp:[email protected]
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