Subject: [Simple] Presence data format extension

From: BECKMANN MARK <[email-masked]>
Date: Thu, 11 Apr 2002 04:43:33 +0200

Hello,

this may be rather a question to the impp WG, but hopefully someone on this
list can also help me, so that I dont have to subscribe to yet another
list;). 

I would like to know if my understanding is correct that basically each
implementor is free to develop his/her own presence data format extension in
particular additional value types and that the extensions are then just
identified by a unique xmlns without having to register the new status value
types and/or create a new RFC to describe those extensions.

Now, if my understanding is correct I wonder whether it is necessary to
define any status values beyond a very limited set at all. The schema
attribute allows each recipient of presence data to find out about the data
format. The limited set of specified status values would allow
interoperability without having to check the data format or semantic
description. For any status information beyond that, interoperability is
achieved by providing information about the data format in the schema
attribute. Of course it is then still open how a user will find out about
the meaning of the status values. Couldn't an additional link pointing to
the semantic description of the extensions solve this problem? 

Thanks,

Mark

Mark Beckmann			Siemens AG

ICM MP PO8 SA 82
P.O.Box 100702			phone: +49 (5341) 906 1814
D-38228 Salzgitter   		fax:   +49 (5341) 906 2010

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From: "Adrian Bateman" <[email-masked]>
Date: Fri, 12 Apr 2002 12:09:22 +0100

> types and/or create a new RFC to describe those extensions.

Well, yes, anyone can create a new extension to the presence data format
using xmlns and abiding by the extensibility mechanism described in the
draft. As far as status values are concerned, we're just working up a
more refined solution to that in the published draft (in fact, we'd
welcome comments from anyone on the recent discussion - you can get to
the mailing list archives from http://www.imppwg.org/), but you can
provide different status value ranges too.

> the semantic description of the extensions solve this problem? 

In terms of interop, I fully expect there to be standard extensions
published. In fact, while we only deal with the RFC 2778 terms OPEN and
CLOSED directly, I think a set of standard IM status values is essential
including the usual things like "busy" and "away". We didn't want to
hold up the already tortuously slow process of producing the IMPP
presence draft by trying to get agreement on this, which is why it will
be an extension. It will be important for different user agents which
might use different protocols on opposite sides of a CPIM gateway to
have agreed on the meaning of the status values.

I've seen it mentioned that this might be a possible work item for this
group. I expect the discussion would be a bit of a religious debate
including things like "do we need busy and do-not-disturb, are these the
same thing, and if they are, which do we use" but it will have to be
done in the end.

Regards,

Adrian.