[Simple] RE: [xmppwg] RE: Action Item: character mappings for interoperabi lity

[Adam Roach <[e-mail]>]

Joe:

I think the fundamental disconnect here between
what I was trying to say and what you are hearing
is this:

 - the JID "[e-mail]" is NOT necessarily
   the same resource as "im:[e-mail]"

 - the JID "[e-mail]" is NOT necessarily
   the same resource as "sip:[e-mail]"

 - The resource "im:[e-mail]" is NOT
   necessarily the same resource as "sip:[e-mail]"

So, for any solution to work, the SENDER must have the
ability to select a *scheme* -- otherwise, there will be
resources that the sender cannot contact.

/a 

> -----Original Message-----
> From: Joe Hildebrand [mailto:[e-mail]]
> Sent: Monday, December 15, 2003 17:33
> To: [e-mail]; '[e-mail]'
> Subject: [xmppwg] RE: Action Item: character mappings for
> interoperability
> 
> 
> Hm.  I guess I need to show more of my work.  I had assumed 
> that on the XMPP
> side, the system entity that does server-to-server delivery 
> would do either
> something like draft-daigle-napstr-03.txt, or something even 
> simpler, like
> draft-ietf-impp-srv-04.txt, except with the "hard" DNS stuff 
> moved to the
> server.
> 
> 1) SRV: do you support XMPP?  If so where?  (resend using XMPP S2S)
> 2) No?  Ok, SRV: do you support SIMPLE?  If so, where? 
> (protocol transcode,
> resend using SIMPLE)
> 3) No?  Ok, SRV: do you support Wireless Villiage?  If so, 
> where? (protocol
> transcode, resend using the WV S2S protocol) 
> 4) No?  Ok, maybe you're an older or less sophisticated XMPP 
> implementation.
> I'll look up your A record, and connect on 5269/tcp.  (resend 
> using XMPP
> S2S)
> 
> <aside>
> NAPTR may be overkill, since in practice, we find it hard 
> enough to get
> customers to install SRV records...  The DNS admins make the 
> LDAP admins
> look helpful. :)
> </aside>
> 
> And something similar on the SIMPLE side.  More-or-less 
> obviously, the order
> of the above should be a policy decision on the part of an 
> admin.  Given
> that, I'm not sure that allowing a user to explicitly go around the
> site-wide policy is a good thing. 
> 
> Really, the only question I had was on step 2) above.  If I 
> determine that
> the other side would rather talk SIMPLE than XMPP, what 
> address do I put on
> the message?  sips: or im:?
> 
> -- 
> Joe Hildebrand
> 
>  
> 
> > -----Original Message-----
> > From: Ben Campbell [mailto:[e-mail]] 
> > Sent: Monday, December 15, 2003 2:52 PM
> > To: Adam Roach
> > Cc: 'Joe Hildebrand'; [e-mail]; '[e-mail]'
> > Subject: Re: [Simple] RE: [xmppwg] Action Item: character 
> > mappings for interoperability
> > 
> > Is the context of this thread IM only, or do we also care 
> > about presence? I am not sure the issues are always exactly 
> > the same, since IM addresses may be delivered as part of presence.
> > 
> > I wonder (vaguely) if draft-daigle-napstr-03.txt is 
> applicable here. 
> > Also, if I recall we _do_ have guidance on how to map an im: 
> > url to a concrete service using SRV, don't we? It seems to me 
> > that if I am a SIP user, the only real hope I have of 
> > cross-protocol interoperability is to advertise a PRES or IM 
> > URI. Other systems may be able to reach SIP URIs on an ad-hoc 
> > basis, but the abstract schema provide a more general approach.
> > 
> > More inline:
> > 
> > Adam Roach wrote:
> > 
> > > I'm cross posting this to SIMPLE to help cross-pollinate 
> some ideas 
> > > here.
> > > 
> > > Joe Hildebrand [mailto:[e-mail]] wrote:
> > > 
> > > [huge snip]
> > > 
> > > 
> > >>Example: josé#26;bó[e-mail] becomes 
> > >>im:jos%c3%a9&[e-mail]
> > >>(note for the MIME-impaired: that's jose' and bo'b)
> > >>
> > >>Actually, it's not clear to me from RFC 3428 whether I 
> > should map into 
> > >>sip:, sips: or im:; I could use some guidance here from 
> the SIMPLE 
> > >>folk.
> > > 
> > > 
> > > Well, they're all (potentially) different namespaces. In 
> > particular, 
> > > there's nothing (other than a possible site-local policy) 
> > that would 
> > > ensure that "im:[e-mail]" would map to the 
> same user as 
> > > "sip:[e-mail]" -- so, you need to have some 
> > mechanism by 
> > > which a distinction is performed. I'll get to that in a second.
> > > 
> > > By contrast, "sip:[e-mail]" and 
> > > "sips:[e-mail]" *will* always refer to the same
> > > user:
> > > 
> > >    Any resource described by a SIP URI can be
> > >    "upgraded" to a SIPS URI by just changing the scheme, if it is
> > >    desired to communicate with that resource securely.
> > > 
> > > So, when you get to a gateway that is going from XMPP to 
> > SIP, I would 
> > > posit that selection of "sip:" would be appropriate when 
> SASL isn't 
> > > being used on the XMPP side, and that "sips:"
> > > would be appropriate when it is.
> > > 
> > > Now, for the issue I deferred: when a message arrives for a 
> > jid, how 
> > > do you know what to do with it? Let's imagine that I send 
> > an IM (from 
> > > an XMPP client) to the jid "[e-mail]". If my 
> > > understanding is correct, this *must* end up being routed to the 
> > > server indicated by the xmpp-server SRV record for 
> > "jabber.com." So... 
> > > does that server attempt to deliver it to an XMPP account called 
> > > "[e-mail]"? Does it gateway it to 
> > > "im:[e-mail]"? Does it gateway it to 
> > > "sip:[e-mail]"?
> > > 
> > > One answer would be "selection amongst those destinations 
> > is going to 
> > > be based on local configuration at the jabber.com XMPP 
> > server, since 
> > > it 'owns' the jabber.com namespace." And that would work, 
> > sort of, and 
> > > be consistent and simple.
> > > 
> > > But it's a very incomplete solution.
> > > 
> > > On a grander scale, we need to ask: if you are sitting at an XMPP 
> > > client as "[e-mail]", and want to send an IM to 
> > > "sip:[e-mail]", how do you do that? Can we 
> assume that 
> > > "dynamicsoft.com" is running an XMPP to SIMPLE gateway? Can 
> > we assume 
> > > that jabber.com is? Should this be able to work if the XMPP 
> > to SIMPLE 
> > > gateway is owned by yet a third domain?
> > > 
> > > I think all three solutions need to be possible.
> > > 
> > > We've already discussed how the first would work; that's easy.
> > > The scheme to use in translation is a matter of the 
> > destination server 
> > > configuration, potentially selected on a user-by-user basis.
> > 
> > I'm not sure I agree on this. As you mention above, even if 
> > dynamicsoft.com maintains an xmpp to simple gateway, there is 
> > no reason to expect that you can infer an identifier that 
> > makes sense to the xmpp side of the gateway from a SIP URI. 
> > If dynamicsoft maintains such a gateway, then it would make 
> > more sense to advertise an xmpp identity in addition to the 
> > SIP identity, or perhaps an im: URI for both.
> > 
> > It seems to me that an xmpp device, presented with a SIP URI, 
> > can do nothing intelligent with it beyond submitting it to 
> > some xmpp-sip gateway that it _already_ knows about, and it 
> > cannot use the SIP URI to discover that gateway.
> > > 
> > > The second would require some indication from your client to your 
> > > server (the host indicated by the xmpp-client SRV record for
> > > jabber.com) that you want to break out to a SIP network.
> > > I don't know enough about the formatting of jids to propose 
> > something 
> > > ideal, but I would think that using some sort of 
> locally-configured 
> > > prefix would provide that sort of indication (e.g. 
> sending an IM to 
> > > "sip#x3A;[e-mail]" would indicate to your 
> > server, by the 
> > > presence of "sip#x3A;", that it should gateway to 
> > > "sip:[e-mail]" using its SIMPLE gateway functionality 
> > > instead of finding the XMPP server for dynamicsoft.com). In 
> > this case, 
> > > the proper scheme to use is explicitly indicated by the user.
> > > 
> > > The third case will require using a jid that explicitly 
> > routes to the 
> > > third-party gateway; for example, 
> > > "adam#40;[e-mail]". (Ideally, this 
> > > ugliness would be hidden behind some sort of user interface 
> > construct 
> > > that allows users to configure their default SIMPLE 
> > gateway). For this 
> > > case, the scheme is decided by the gateway itself, and will 
> > typically 
> > > be specific to the protocol mapping provided by that 
> > gateway (i.e. a 
> > > gateway that translates to SIMPLE will always use sip: or 
> sips:, as 
> > > appropriate).
> > > 
> > > At least, that's my two cents on the topic.
> > > 
> > > /a
> > > 
> > > _______________________________________________
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> > > [e-mail]
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> > 
> > 
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