[Standards] XEP-0220 unclear?

Philipp Hancke fippo at goodadvice.pages.de
Tue Apr 20 06:36:00 UTC 2010

Hi Luke,
> I've ran on some hickup during server dialback implementation. Mr. Saint-Andre recommended me to post a message here. Here's this exact problem (only 4 years ago) with stanzas to follow:
> http://mail.jabber.org/pipermail/jdev/2006-July/083520.html
> I'd be grateful for any pointers.

That is described in section 2.1.2:
"To do so, either it can reuse an existing XML stream or it needs to
  establish a new connection."
or in step 5 in RFC 3920, section 8.3:
"(Note: As an optimization, an implementation MAY reuse an existing
  connection here.)"

The order of dialback steps described by Ben is:
ME-GT  --> step 1
GT-ME  --> step 1
ME2-GT --> step 2
ME2-GT <-- step 3
GT-ME  --> step 4
GT-ME  <-- step 2
(connection identifier, stanza direction, dialback step)

GT is a little impolite by initiating it's own dialback before sending
the verification key. While that is a valid optimization, it makes
dialback flows very hard to read.
XEP 220 recommends (see 2.1.1) that the originating server does not 
initiate dialback unless it has queued any stanzas for the peer.

hope that helps


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