[standards-jig] XMPP compatibility discovery

Jacek Konieczny jajcus at bnet.pl
Wed May 21 16:42:50 UTC 2003

On Wed, May 21, 2003 at 08:42:54AM -0700, Iain Shigeoka wrote:
> On 5/21/03 0:18, "Jacek Konieczny" <jajcus at bnet.pl> wrote:
> > But things get more complicated for server application. They should send
> > new error messages to XMPP compliant clients, but should not do that to
> > old Jabber clients (which will be still popular for some time). Of
> > course server could send something like this:
> Actually you'll know based on the stream itself. So the server will know
> it's talking to an XMPP 1.0 compliant client by looking for the 'version'
> attribute on the stream set to '1.0' as per spec:
> http://www.jabber.org/ietf/draft-ietf-xmpp-core-12.html#xmlstreams
> Once you know the stream is xmpp 1.0, you should send xmpp error messages
> instead of jabber ones. The lack of the version attribute indicates an old
> jabber client and should be sent the old jabber error packets.

I am writting a transport gateway, which behaves like server entity, but
is not directly connected to client. Also remotes server may be able to
generate both types of errors, but they won't know if client they talk
too understands XMPP errors.

> The hard part for the server (or the spec in general) is deciding how to
> handle error messages between clients on different versions. E.g. Is it the
> server's responsibility to read error messages and translate them between
> streams if one client is old jabber, and the other is xmpp.

Old errors are not very well translatable to the new style. It is easier
in the other way, but this requires the server the client is connected
to to be XMPP compliant and able to translate error stanzas. We don't
even have a working XMPP server now, and this limits developement of XMPP
clients and services.


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