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

Carlo v. Loesch CvL at mail.symlynX.com
Wed May 17 16:33:52 UTC 2006

Jean-Louis Seguineau typeth:
| > We're only talking about leaving out 'to' on the S2S wire.
| I am just saying this breaks section 9.1.1 of RFC3920 for s2s, not

Well obviously as this is an extension to the RFC, we cannot remain
compatible to it. In fact, when XMPP was about to be published as an
RFC, we suggested that the one-to-many issue needs attention and XMPP
should provide for a means of multicasting. Back then several people
presumed multicast would never become necessary, so the RFC came out
with multicast inability builtin.

Now you have come to the point that multicast is useful after all,
and we are patiently here again and even proposing how to do it.
Obviously we can't stick to an RFC which was conceptually built
against multicast, that's why we are suggesting to give this new
syntax a new XMPP version number.

I'd also like to add a statement Larry Masinter made on the IMPP
Mailing List on Oct 18, 1999:

    "If you're going to do a standard for Instant Messaging (even 1-1 messaging), ignoring the requirements imposed by the possibility of group communication would likely lead you to a protocol that doesn't satisfy anyone's actual requirements."

IMPP was then designed without one-to-many in mind, even though
the mere plan of distributing presence IS a one-to-many operation.
And here we are, 7 years later, and we know Larry was right.

| My point was only about protocol level compliance. But now that Till started
| on this, the JEP assumes the rosters to be properly synchronized on every
| server. There is no guarantee it would always be the case. You will have to
| explain how you will cater for it. That is probably a tougher nut to
| crack...

If the rosters are not in sync, it doesn't matter if they aren't in sync
on the sender's or on the receiver's side. If so far you were able to live
with occasional glitches and occasional necessity to re-establish a
subscription, the multicast variant of the operation won't make that more
or less complicated. It only gives you less traffic on the network.

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