Subject: [xmpp] 3921bis: 8.2. Remote Domain

From: Jonas Lindberg <[email-masked]>
Date: Thu, 22 Jul 2010 13:49:43 +0200

http://tools.ietf.org/html/draft-ietf-xmpp-3921bis-08

   2.  If the "xmpp-server" address record resolution fails, attempt to
       resolve the "_im" or "_pres" SRV Service as specified in
       [IMP-SRV], using the "_im" Service for <message/> stanzas and the
       "_pres" Service for <presence/> stanzas (it is up to the
       implementation how to handle <iq/> stanzas). (...)

What is the reason for decoupling the two? Might be helpful to include
a brief sample scenario.

Does it really make sense to decouple the two without any guidelines
on what to do for <iq> stanzas? Wouldn't one expect issues if
implementation handle <iq> stanzas differently?

Jonas

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From: Justin Karneges <[email-masked]>
Date: Thu, 22 Jul 2010 15:43:34 -0700

> implementation handle <iq> stanzas differently?

CPIM defines the im and pres services as being separate, and so XMPP is trying 
to comply.

However, I'm not quite sure why you'd fallback from XMPP to generic CPIM 
delivery.  CPIM tells you what protocol is supported by the destination 
domain, avoiding any need to blindly attempt specific messaging protocols.  I 
would think that a server supporting multiple protocols would always start 
with im/pres resolution *first*..... ?

-Justin

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From: Peter Saint-Andre <[email-masked]>
Date: Sat, 24 Jul 2010 05:24:14 -0600

[Typed while in transit, delivery will be delayed.]

> with im/pres resolution *first*..... ?

Given that _im and _pres are not very widely deployed (jabber.org might
be the only IM service in existence that has the proper SRV records, and
I did that mostly on a lark), I don't know if we want to give priority
to those SRV records over _xmpp-server.

Peter

-- 
Peter Saint-Andre
https://stpeter.im/

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From: Justin Karneges <[email-masked]>
Date: Sat, 24 Jul 2010 13:13:26 -0700

On Saturday 24 July 2010 04:24:14 Peter Saint-Andre wrote:
> > CPIM defines the im and pres services as being separate, and so XMPP is
> > trying to comply.
> >
> > domain, avoiding any need to blindly attempt specific messaging
> > protocols.  I would think that a server supporting multiple protocols
> > would always start with im/pres resolution *first*..... ?
>

The CPIM records do have priority, but only for servers supporting multiple 
protocols.  If your server supports both XMPP and SIMPLE, for example, and it 
needs to deliver a message to example.com, then the most appropriate approach 
is for it to resolve "im" to see what protocol the destination server uses 
(read: XMPP or SIMPLE), and then use that protocol to send the message.

If your server only supports XMPP, then it can skip "im" and jump straight 
to "xmpp-server".  To be clear, this is not a change in priority, but rather 
that "im" is made irrelevant in an XMPP-only context.

In short, the CPIM records have priority, but in nearly all deployments they 
shouldn't be used.  Like that? :)

-Justin

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From: Peter Saint-Andre <[email-masked]>
Date: Sun, 25 Jul 2010 13:58:10 +0200

> shouldn't be used.  Like that? :)

Heh. :)

I'll make some inquiries about _im and _pres among those who might have
cared about them in the past, and think about the issues some more as
well. But your suggestion probably works.

Peter

-- 
Peter Saint-Andre
https://stpeter.im/