[Standards] summary: allowable characters

Mridul Muralidharan mridul at sun.com
Sat Aug 4 23:40:13 UTC 2007

Robin Redeker wrote:
> On Fri, Aug 03, 2007 at 04:29:15AM +0530, Mridul Muralidharan wrote:
>> Just mentioning a basic problem which was discussed at jdev.
>> If two 1.0 server move to 1.1, all the 'older' 1.0 jid's will become 
>> unroutable - which are present in user roster/affiliations/privacylists/etc.
> Yes, this sounds like the death blow for escaping for backward
> compatibility. It will poison the old 1.0 servers and make whole roster
> subscriptions unusable once that server upgrades to 1.1. (Not to mention
> the JIDs in the private XML storage or other places you mentioned).
> Do you see any problem in just disallowing incompatible 1.1 JIDs to be
> able to communicate with 1.0 JIDs? The old 1.0-compatible JID accounts
> on a 1.1 server will of course still be able to talk with people on 1.0
> servers.

The problem is 1.1 JID's cant communicate with 1.1 contact JID's -
if user has cont\26ct at domain, what will the 1.1 server do ? It could 
either be pointing to a 1.1 cont\26ct at domain (route as-is), was a 1.0 
jid - convert to cont&ct at domain (needs transformation) or continues to 
be 1.0 cont\26ct at domain (route as-is) (all three as different cases, 
though 1 and 3 look the same).

> The network won't be split the day servers start speaking XMPP 1.1.
> By preventing people with JIDs with incompatible characters to speak
> with 1.0 servers the 1.1 servers can prevent that split.

Existing data will be present - and without jid meta-data, we cant 
associate encoding info.

One possible option would be to move to use uri scheme for jid's - (and 
so this could be the differentiator for 1.1 vs 1.0).
More importantly, it would help in case of interop with other protocols.

Last time I brought this up, it was considered a bit too disruptive, and 
so dropped :-) Since Peter was considering 1.1 of xmpp, maybe this would 
be a good time to rethink this idea !


> The 1.1<->1.0 gap will grow with people who want to use the new
> characters in their JID, and hopefully the server administrators also
> upgrade their servers at the same speed that these people come.
> Clients would also have to take care whether they speak to a 1.0 or 1.1
> server. A client error message like: "your server doesn't support these
> characters in the JID, convince the admin to upgrade!" will maybe even
> raise the pressure for admins a bit to upgrade :-)
> The problem with forcing admins to upgrade I see here is that they are
> maybe forced to upgrade to a unstable version or not so stable version
> as they had before.
> Robin

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