[Standards] UPDATED: XEP-0220 (Server Dialback)

Dave Cridland dave at cridland.net
Tue May 17 18:04:49 UTC 2011


On Tue May 17 18:55:22 2011, Peter Saint-Andre wrote:
> On 5/17/11 11:51 AM, Dave Cridland wrote:
> 
> > Versioning is *nearly* always the wrong thing to do.
> 
> http://mail.jabber.org/pipermail/standards/2008-September/019763.html

In the message you quote, I continued:

"""
Our namespace versioning is not versioning of the protocol in this  
sense, because that would imply that "urn:xmpp:features:dialback:0"  
is a subset of "urn:xmpp:features:dialback:1", whereas no such  
assertion exists - the two are entirely unrelated from a protocol  
standpoint, and any similarity is merely in the familial sense -  
they're likely to have both been specified in the same document at  
different times.

But - crucially - no compatibility is asserted; indeed the precisely  
opposite assertion is made: the two protocols are mutually  
incompatible.
"""

This matches what I originally proposed in the message of mine you  
have cited above:

"""
urn:xmpp:protoname:1

That last portion we'll treat as a version number. Any time we cause   
incompatibility between versions of the XEP, we update it. (Note,   
that's not "every new XEP").
"""

Note use of the word "incompatibility". The use of the term "version"  
is, I agree, confusing, but my point here is that by changing the  
namespace version number, we're actually both signalling, and  
causing, an incompatible variant of the protocol.

I don't think the variants of dialback in discussion here are  
incompatible within the subset currently defined.

Dave.
-- 
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