[Standards-JIG] LAST CALL: JEP-0106 (JID Escaping)

Peter Saint-Andre stpeter at jabber.org
Tue May 3 23:19:58 UTC 2005

On Thu, Apr 21, 2005 at 10:43:11PM +0100, Richard Dobson wrote:
> >Well, as pointed out in this morning's Jabber Council meeting, I was
> >looking at the transformations only in one direction. It is perfectly
> >valid to have domain names that start with 20, 22, 26, 27, 2f, 3a, 3c,
> >3e, and 40. Consider the case of an MSN user whose email address is
> >up at 3am.com ... once transformed by an MSN gateway, that person's JID
> >might be:
> >
> >up%3am.com at msn.example.com
> >
> >However, the characters %3a are now ambiguous: do they signify "@3a"
> >through an MSN gateway or ":" as decoded in JID escaping? Thus an
> >an application would have no programmatic way of distinguishing
> >between the following interpretations of that JID:
> >
> >1. an entity whose decoded node identifier is "up at 3am.com"
> >
> >2. an entity whose decoded node identifier is "up:m.com"
> >
> >Ambiguity is bad because it breaks things. And one of our cardinal rules
> >is not to break things.
> >
> >Therefore the Council has decided to retain the #xx; escaping mechanism
> >for the 9 code points (and only for the 9 code points) that are
> >explicitly disallowed in the Nodeprep profile of stringprep. While this
> >prevents conforming applications from re-using existing URI-processing
> >libraries for the purpose of JID escaping, the Council decided that
> >that's slight hardship when special-casing the 9 code points in the node
> >identifier portion of JIDs, and to proceed with advancement of JEP-0106
> >as-is (actually, with some slight wording changes that I am working on
> >now).
> >
> >A transcript of the Council discussion is here:
> >
> >http://jabber.org/muc-logs/council@conference.jabber.org/2005-04-21.html
> >
> >Feedback is welcome as always.
> I would have to argue that its an equally slight hardship to alter the 
> existing MSN transports so we can just use the internet standard, plus how 
> many MSN users actually have addresses that could present a problem in any 
> case?? Certainly on my MSN contact list which is about 92 people 86 have 
> @hotmail.com or @msn.com addresses and of the remaining ones none of them 
> have domains that could cause a problem.
> Overall I truely fail to see the problem here from a real world point of 
> view and as far as I can see it seems an entirely theoretical problem and 
> thus shouldnt be holding us back from doing things properly.

The question is: what is the proper thing to do?

Some feel that percent-encoding is the proper approach. That is the
approach used in transforming disallowed characters in URLs/URIs.

Peter Saint-Andre
Jabber Software Foundation

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