Just now catching up...

On 11/24/09 1:15 PM, Brian Cully wrote:
> On 24-Nov-2009, at 15:08, Robin Collier wrote:
>> I would assume that you are going to request with the latest version
>> by virtue of the natural order of the version string, not by time.
> 
> No, because there is no natural order to an opaque string. Instead, you
> rely on the in-order delivery semantics of XMPP and go with the most
> recently received stanza. In truth, it doesn't really matter what stanza
> you pick, though, as long as you pick a version you've seen.

Right. This is exactly how we do things for roster versioning: when
requesting the roster, you tell the server "this is the last version I
know about" and it either (1) informs you that you're up to date or (2)
sends you what's new. I don't (yet) see any strong reason to do things
differently for pubsub.

And, to be clear, in order to tell the server "this is the last version
I know about" you don't need to tell the server "I last received an
update from you at Time X" because I can just as easily tell the server
"the last update I received from you was Version Y". The two are
functionally equivalent as far as I can see.

Now, people might want timestamps for other reasons, but so far we've
thought that timestamps are better encapsulated in the payload than in
the payload wrapper (<item/> element).

Peter

-- 
Peter Saint-Andre
https://stpeter.im/


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