Subject: Chicago MMUSIC WG minutes

From: Mark Handley <[email-masked]>
Date: Thu, 17 Sep 1998 10:31:05 -0400

MMUSIC Minutes from the Chicago IETF
====================================

Reported by Eve Schooler, Mark Handley, and Joerg Ott

Colin Perkins made a brief presentation on changes to the SAP security
specification made as a result of comments on the mailing list.  Mark
Handley will merge the security spec with the base spec and submit
this to the IESG to become an experimental standard before the next
IETF.  An issue was raised whether these changes to the SAP
specification required the version number to change; the previous
version of the draft had inadvertantly changed the version
number. However, Mark Handley pointed out that implementations of the
previous SAP security did not exist so that the existing version
number could be re-used.

Mark Handley summarized the status of SIP: we have completed WG last
call and submitted the spec to the ADs.  The ADs felt that performing
IETF last call over the IETF was a bad idea so delayed that until
after the IETF.  In the meantime a couple of errors had shown up in
the SIP spec.  Besides pure editorial errors such as the consistent
use of IETF standards terminology and the need for some explanatory
clarifications, a couple of functional errors were discovered.
Henning Schulzrinne described these errors and the proposed solutions
including the following: a new error code was added to allow
distinction between a busy signal from one (out of many) call legs
from a (final) busy signal (on the single or all legs) of a call.  An
expiration field was added to the "Location" header to allow reporting
independent reporting of different expiration times for each location.
Finally, an open issue was reported with respect to the "Location"
syntax: in SIP, a "Location" header may be following by several URIs
each which associated parameters -- the separator between them being
commas and semicola, respectively.  In case a URI contains either of
the separating character (which is unlikely but possible), this will
result in misinterpretation of the "Location" header.  Proposed
solutions include quoting each URI, allowing only a single URI per
"Location" header, and using '<' and '>' as delimiters for the URI
similar to the mail address format, and changing the name of the
header.  The rough consensus was to change the name of Location to
Contact and to allow '<' and '>' as delimiters.

A new ID will be submitted as soon as the ID editor is accepting IDs
again, and we will ask the ADs to do IETF last call on this revised
spec instead.  The consensus in the room was that the changes were
small enough that we didn't need to repeat WG last call.

Colin Perkins presented a proposal for a local message bus for local
area conference coordination, similar to the LBL conference bus, CCCP
and PMM.  Such a proposal was first made in MMUSIC at the 1994 Seattle
IETF and has been discussed occasionally since. There seemed to be a
lot of interest in this proposal now.  It is not clear that this
should be an MMUSIC work item though, as it has the potential to be
used for more general purpose local coordination.  The rough consenus
was that work on this should continue, and that we should consider
holding a BOF at the Orlando IETF to see if the interest is general
enough to form a new WG.  The authors of the Mbus documents agreed to
consider the implications of a broadened scope of the Mbus with
respect to their design decisions as well as the potential overlap
with other WGs (or BOFs) in the IETF before deciding on requesting a
BOF for the 43rd IETF.

Philip Hoschka presented a proposal for a syntactic mapping of SDP
into SMIL (W3C's Synchronised Multimedia Integration Language).  The
rough consensus was that this was the wrong approach -- SDP is quite
limited and there is no reason why these limitations should be
perpetuated in SMIL.  Instead, a description language much more
powerful than SDP would be desirable in many cases.  It was also
pointed out that providing SMIL definitions that follow what is in SDP
faces the problem of a SDP being a moving target: this would lead to
this part of SMIL always being slightly out-of-sync with SDP and may
even result in diverging specifications.  Inclusion or referencing SDP
as is was conceived a more suitable alternative.  However, we want to
ensure that the IANA registry used for SDP can also be used for SMIL
so the two should share some common syntax.

Francois Menard presented some ideas for using XML in the context of
SIP for conveying more general information such as settlements.  This
wasn't a specific proposal -- more a heads up for people to think about
this possibility.

Kenji Fujikawa presented a proposal for SIP URLs.  Mark Handley
presented the reasons why he thinks this is a bad idea.  Much
discussion ensued which was curtailed because we ran out of time, but
the consensus appears to be that is this a bad idea and should not be
persued.  If you absolutely need this information in a URL, use the
data URL instead.  But preferably don't do it at all.

Slides from the presentations and these minutes will be made available
on the MMUSIC archive site at ftp://ftp.isi.edu/confctrl/minutes.