[Standards] Link-Local Messaging comments

Justin Karneges justin-keyword-jabber.093179 at affinix.com
Tue Mar 13 20:29:06 UTC 2007


> >   In section 6 it says that the stream opening should have no 'to' or
> > 'from' attributes. Which is kinda unfortunate. This means that when
> > someone opens a new connection to me, the only information i have is the
> > ip the connection originated from. If the machine where the connection
> > originated from has multiple presence, i'll have to wait untill the first
> > stanza containing a 'from' attribute is received before i can link a
> > connection to a presence.. If there would be a 'from' attribute in the
> > stream opening, it would obviously be much easier/elegant.

That's how the protocol works though.  If you depend on this attribute being 
present, then you'll lose iChat compatibility.

IMO, it makes a lot of sense for the stream to not identify a particular 
account during the initial negotiation.  Like s2s, Link-local simply links 
two systems, and identification of accounts is better placed in the stanzas 
themselves (which allows multiplexing of one TCP connection for many stanza 
senders/receivers).

Unfortunately, iChat doesn't multiplex chats over one connection like this.  
Instead, it explicitly ties a TCP connection to a contact.  For example, 
closing a TCP connection is considered to have a meaning similar to 
the "Gone" XEP-85 chat state.  Weird...  but this is how iChat works.

So, as much as we can talk about better ways of doing Link-local (what you 
did), or assumptions/possibilities about the current design (what I just 
did), it's all kind of moot if we want to retain iChat compatibility.

> Ah. I'll change that, since we modified it in rfc3920bis too:
>
> http://www.xmpp.org/internet-drafts/draft-saintandre-rfc3920bis-01.html#str
>eams-attr

What was the rationale for this?

-Justin



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