[jdev] Namespace IRI handling when forwarding stanzas between c2s and s2s links

Wed Nov 30 05:36:47 CST 2005

Hi!

I am currently finishing namespace support for the next release of 
jabberd14. One remaining thing that is not completely clear to me is the 
handling of the different namespace IRIs on c2s- and s2s-links. 
Currently I am just mapping all three namespaces 'jabber:client', 
'jabber:server', and 'jabber:component:accept' to the same jabberd14 
internal namespace. When I am serializing the stanzas, I check which 
type of connection the stanza is serialized on and use the standard 
namespace IRI for this type of connection.

The problem I have with that is the following:

Assume a client sends the following stanza:

<message xmlns='jabber:client' from='user1 at example.com' 
to='user2 at example.com'>
    <body>Some example stanza, that is not very useful, but should 
demonstrate my problem</body>
    <x xmlns='http://example.com/someStrangeExtension'>
        <presence xmlns='jabber:server'/>
    </x>
</message>

This stanza gets delivered to user2 as:

<message xmlns='jabber:client' from='user1 at example.com' 
to='user2 at example.com'>
    <body>Some example stanza, that is not very useful, but should 
demonstrate my problem</body>
    <x xmlns='http://example.com/someStrangeExtension'>
        <presence xmlns='jabber:client'/>
    </x>
</message>

(Note the namespace switch for the <presence/> element.)
Is this namespace change allowed, or is this an error?

In that simple case I could keep the namespace of the presence element 
intact very easily by just switching namespaces, when resending from one 
connection type to another. But it gets more complicated when user2 is 
on another server and I have to use s2s. In that case <message/> and 
<presence/> for sure are send as 'jabber:server' to the other server. 
But how does the other server know, that only the namespace of the 
<message/> element has to be mapped back to 'jabber:client' before delivery?

Tot kijk
      Matthias