[dispatch] Comments on draft-saintandre-sip-xmpp-presence-04

[Michael Lundberg <[e-mail]>]

Peter,

Thanks for resubmitting the SIP-XMPP presence I-D.  I think this and
the other documents are important as there are a lot of interworking
issues today with XMPP and SIP/SIMPLE implementations, and I think
these documents can help reduce some of those interworking challenges.

In order to help ensure interworking between different
implementations, I think Sections 5.2 and 5.3 need to have some
stronger ‘MUST’ language instead of SHOULDs, MAYs, etc.  This will
enforce proper and complete mappings between implementations that
conform to this document.

While I don’t think the document needs to enforce the use of the
<show/> element mapping discussed in 5.2, I think if implementations
are going to use the mapping, this document should enforce the use of
a specific namespace and describe the mapping of <show> values
specified in RFC 6121 (i.e., away, dnd, chat, and xa).  This will at
least allow a minimum set of standard mappings between XMPP and SIP,
which can be expanded on in future document(s).  Section 5.3 could
then also discuss how this mapping can be accomplished from SIP to
XMPP if the SIP endpoints/devices support this same namespace.  One of
the big interworking challenges with today’s implementations is the
use of different namespaces given the extensibility of XML-based
presence standards (e.g., PIDF, RPID), which allows individuals to
create their own namespace.  This flexibility is good for ingenuity,
but problematic for interworking between different implementations.  I
think standardizing a basic set of common status information using a
specific namespace is needed, and this document is a good place to do
that.

In my opinion, I do not think Section 6 should be part of this base
document.  While I like the idea of encapsulating the SIP <presence>
information into the XMPP message, I think this content should be a
consideration for implementing ‘rich presence’.  As written, this
method is only applicable for SIP to XMPP translation, and if the
focus of this document is just ‘basic’ presence information
interworking, the SIP to XMPP mapping in Section 5.3 already describes
a method for how this can be accomplished.

Regards,
Michael