[JDEV] PubSub (0060) Max_items -> Range?

Timothy Carpenter timbeau_hk at yahoo.co.uk
Mon May 19 19:08:37 CDT 2003

This is a valid point, but what if the subscriber does not know how many
have been missed?

A  subscriber may re-subscribe after an enforced/unplanned outage and wish
to get back up to date. It does not know how many events it has missed. Time
does not solve it (for what is...time?). For pubsub to be functional it
needs a form of sequence numbering and, thus, gap filling, an example of
which was proposed in JEP0032.


On 19/5/03 7:39 pm, "Matt Mankins" <mankins at media.mit.edu> wrote:

> In thinking about client interaction with pubsub nodes today I realized
> that it might sometimes be useful for clients to request a range of items
> from a node (this is modified example 50):
> <iq type="get" from="pgm at jabber.org" to="pubsub.jabber.org" id="items2">
> <pubsub xmlns="http://jabber.org/protocol/pubsub">
>   <items node="generic/pgm-mp3-player" range="10-20"/>
> </pubsub>
> </iq>
> We have max_items already, which suggests:
> "When max_items is used, implementations SHOULD return the N most recent
> (as opposed to the N oldest) items."
> ...so there already exists a notion of "counting" to the items.
> Range requests would be useful for low-bandwidth clients as well as for
> high-volume nodes.
> Since range is actually more general than max_items, it might be
> preferable to replace max_items with range.  ie-- range="0-10" would be
> equivalent to the current max_items="10".
> Matt Mankins
> MIT Media Lab
> http://www.media.mit.edu/~mankins/
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> jdev at jabber.org
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