[Standards] IQ Pubsub again (was Re: Fwd: Meeting minutes 2010-02-15)

Fabio Forno fabio.forno at gmail.com
Fri Feb 19 09:46:05 UTC 2010

2010/2/19 René Treffer <treffer+xmpp at measite.de>:
> I think we are talking about the wrong problem. Things may go wrong,
> everywhere. The only thing that matters would be a stable way for
> "Server, my state is X, is that correct?" -> {"yes", "no", "error"}
> Decreasing the size of X helps, getting good ways to sync helps, trying to
> build endless layers of ack that break randomly won't help much imho.
> Sending a single IQ with the client state, at the clients discretion, wait
> for the reply, and you are done with detecting any kind of inconsistency. At
> least in the cases where the server stores data. Wave had some stuff for
> that, iirc. Running a pubsub without storage is a fire & forget, by
> definition.

Well this is similar to a solution we are adopting for having some
sort of reliability, which is not based on IQs, but needs some more
work and cooperation between the client and the server:

- subscribers have a presence subscription with the pubsub service
- when the client goes online we send the last published item ID
- if the client is not in synch starts pulling items starting from the
last received ID
- while the client is online the server sends events with new item IDs
and the client pulls their payload with IQs

Fabio Forno,
Bluendo srl http://www.bluendo.com
jabber id: ff at jabber.bluendo.com

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