[JDEV] Ambiguity in jabber:iq:browse "pushes"
jens at mac.com
Thu Aug 16 11:37:58 CDT 2001
I'm trying to grok the vague description of jabber:iq:browse on the
"Protocol-Draft" section of the DocZone:
As always, if this is the wrong thing to look at and there's a
conflicting but more accurate description somewhere else, let me know!
The primary thing that's gotten me confused is the apparent ambiguity of
a "set" query using this namespace. It seems to be used for two entirely
(1) Sent to a watcher as a "push" to notify a watcher of new data in the
*sender*s browse space.
(2) Sent to a browse source to edit (add/modify/delete) data in the
*receiver*s browse space.
In general I don't see how these two things can be distinguished from
each other. If you look at the two examples in the "Live Browsing" and
"Editing" sections, they are fundamentally identical; only the type of
data elements in the payload is different. Yet the two have very
different meanings and in fact describe data on two different JIDs! The
sinking feeling I have is that when receiving such a "set" you have to
make a judgment call based on the exact type of data contained and the
exact JID you received the query from. I imagine that this is _usually_
possible, but it makes me nervous and doesn't seem like a good design.
IMHO it's the "push" feature that seems wrong -- it's a misuse of "set".
The exact meaning of "get" and "set" is already pretty vague due to all
the uses they've been put to, but it seems that you can at least rely on
the fact that they apply to the _receiver_ of the query. But browse
pushes turn this on its head.
What this really points out is the lack of a general purpose
subscription/notification mechanism in Jabber, which is ironic since
this is so central to presence. Jabber's <presence> element and its
subscription model are completely hardwired for one particular type of
data (presence state and status text) and cannot be used for anything
else. There is a lot of other info that one might want to subscribe to,
ranging from buddy icons to lists of shared files to news headlines, but
no good mechanism to manage the subscriptions and notifications required
by real-time updates of this information.
Any comments? Am I totally off-base here? Are the existing efforts to
remedy this? (I'm aware of the Profiles JIG and have just joined it.)
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