Re: [xmpp] draft-cridland-xmpp-session-00

Kevin Smith <> Tue, 10 June 2014 08:07 UTC

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Date: Tue, 10 Jun 2014 09:07:05 +0100
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From: Kevin Smith <>
To: Dave Cridland <>
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Subject: Re: [xmpp] draft-cridland-xmpp-session-00
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On Tue, Jun 10, 2014 at 8:43 AM, Dave Cridland <> wrote:
>> This draft will require servers and client changes, you could accomplish
>> the same goal by a pure informational draft pointing such features are
>> optional. Then only certain clients need to change. Note: Good clients like
>> Swift already ignore the session feature.
> Then it's not a good client - the session feature, if advertised, is
> mandatory.

Yeah, I don't believe this is true. Swift treats the session start as
unnecessary, but if it's offered by the server it'll negotiate it. The
relevant code is splattered around

> So if you remove the <optional/> marker from M-Link, every
> conforming client has to negotiate it.

Every 3920/1 client, that is, rather than every 6120/1 client. yes?

> You can't claim that if it's RFC 6121
> only then it's exempt, because then certain servers won't work (I think
> ejabberd is one that actually requires the <session/>, in line with RFC
> 3921).

Right. Clients still need to implement this for old servers (I assume
modern ejabberd /doesn't/ require this, but very old versions are
undoubtedly out in the wild).

I think the draft is roughly the right thing to do. Nits:


<optional/> really isn't what this really is. Is there scope for
naming it <obsolete/>? How widely deployed are clients-servers that
use optional and are unlikely to be upgradable? I'm uncomfortable with
standardising that <optional/> means MUST NOT. If we have to do this,
we should probably add some text that <optional/> is only used in the
context of session startup.