Subject: [Simple] About tuple ids and namespaces in presence data model

From: "Dag Ekengren" <[email-masked]>
Date: Thu, 7 Oct 2004 10:03:51 +0200

First of all, I would like to thank Rosenberg for his initiative with,
draft-ietf-simple-presence-data-model-00. I think the model is very
useful.

I have a few questions that I hope you can shed some light on.

1.	Please correct me where I have gotten this wrong: About the id
attribute of the service tuple.  If I remember correctly, when reading
about tuple-ids some time ago, the id needs only be unique within the
pidf document. It is used to detect if a tuple has been removed or a new
tuple has been added when refreshing the pidf document.

To uniquely identify a tuple on the presence server, you would need to
combine the etag (if PUBLISH was used) with the tuple id.

So it is perfectly valid to have tuple-ids like let's say "1", "2" and
"3" in a pidf document.

The tuple id in the notification generated by the presence server can be
something completely different. So a publisher that is also a watcher to
its own presentity cannot determine if a tuple in a notification is
"his" tuple. This would be difficult anyway with splitting/merging and
so on.

If service tuple were required to have contact uri:s, I guess the
tuple-id would be unnecessary. But that would be incompatible with RFC
3863.
2.	The new elements "person" and "device". I would like to put a
note on the device, would the note element be from the pidf namespace or
do you imagine that this element would be added to the
urn:ietf:params:xml:ns:pidf:person namespace? RFC 3863 says that a tuple
element can have optional note elements, but the person and device
elements aren't tuples, at least they aren't called <tuple>.

Should it be possible to use the RPID attributes within these elements?
In the examples there are activity elements, but it isn't clear what
namespace they are picked from. My guess is that these are indeed the
from the RPID namespace.
3.	Small comment on the samples: the prescaps for audio looks like
this in draft-ietf-simple-prescaps-ext-01: <audio>true</audio>, but in
the presence model samples it is expressed as <audio />. Is this an
intentional change, i.e. is it something that might go into a later
prescaps draft?

Thanks,
Dag

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 11 Oct 2004 16:56:45 -0400

inline.

> tuple has been added when refreshing the pidf document.

Right, that was its intended purpose.

> "his" tuple. This would be difficult anyway with splitting/merging and

Right.

> tuple-id would be unnecessary. But that would be incompatible with RFC

No, even if you have contact URIs, the server still needs to see them 
differently. I could be attempting an override, in which case two 
different PUA would publish tuples with the same service URI. Even if 
you ignore that, if you wanted to allow a publisher to change the URI 
and consider this a change in tuple, as opposed to a new one, you'd 
still need ID. Though I suppose there is hardly a reason to do that.

We don't have an id for the <device> element, which would seeem to imply 
that the device-id+etag form the handle. For services, its id plus the 
etag. I'll make this explicit.

> elements aren't tuples, at least they aren't called <tuple>.

THis is a good point. I would argue that the note in the presence 
document that resides outside of the tuples probably "belongs" to the 
<person>, even though its not within it. Thus, there would not be a need 
for another note element. I think thats consistent with current usage. I 
will add text describing this.

> namespace they are picked from. My guess is that these are indeed the

Per the other thread, rpid is being updated. You will see that the 
various rpid elements are assigned to appear in one of the person, 
device or tuple elements.

> intentional change, i.e. is it something that might go into a later

Bug. I'll fix.

Thanks,
Jonathan R.

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