Subject: SDPv2 and URL's

From: Bill Fenner <[email-masked]>
Date: Mon, 8 May 1995 16:41:58 PDT

The subject of URL's in session descriptions came up today, and I remembered
a comment that I had on the SDPv2 spec.

Three examples out of my sd archives (no, I have no clue why I keep sd
archives.)

i=IVS 3.4 format audio/video on the default ivs multicast address.
Please do not send high rate (> 64 kbps) video with high ttl (>32)
without checking that it does not conflict with others scheduled
transmissions. The current MBone agenda can be looked at
<http://www.cilea.it/MBone/agenda.html>. Further information about ivs
is available at the following URL: <http://www.inria.fr/rodeo/ivs.html>

i=Multicast of keynote and plenary sessions from Washington, DC,
Convention Center. See http://sc94.ameslab.gov for general information
and http://sc94.ameslab.gov/AP/glance.html for schedule. Biology and
Medicine Plenary Thursday at 1:30 pm EST by Christopher Johnson (Utah).
Direct any questions or concerns to [email-masked].

i=World Domination Records, Windswept Pacific, IUMA, Starwave, and Nick
Turner of Firstars Management present the Seattle-based techno/ambient
rock band Sky Cries Mary. For more information visit
http://www.starwave.com/corp/scm/   Email feedback is welcome at
[email-masked]. This is a nv/CellB vat/PCM2 broadcast. Questions
regarding this beoadcast should be directed to Eric Davis
([email-masked]) http://www.classified.com/people/ericd.html

Each of these people found it useful to include multiple URL's for
different types of information.  If SDPv2's u= doesn't provide
similar functionality (i.e. multiple URL's with an optional description
of each one), then people are likely to just put the URL's in the
i= field anyway and defeat the purpose of u=.

I propose to allow multiple u= fields, and associate an optional
description with each one, i.e.

u=http://sc94.ameslab.gov General information
u=http://sc94.ameslab.gov/AP/glance.html Schedule

Since whitespace in URL's should be able to be encoded using the URL
escape mechanism, whitespace should be a sufficient seperator between
the URL and the description.

A description like "Further information" could apply to any URL
without a description, but that's an application thing.

Comments?...

  Bill

(P.S. I am not on confctrl, I have been trying to subscribe for an awfully
long time, so I wrote a program that fetches the archives and inc's the
new messages into my inbox -- so, if you want quick repsonse, cc me on
replies)

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From: Mark Handley <[email-masked]>
Date: Tue, 09 May 95 11:46:41 +0100

>Three examples out of my sd archives (no, I have no clue why I keep sd

..

>without a description, but that's an application thing.

The reason why I suggested a single URL is simply that we should
attempt to move away from full descriptions of sessions in the "i"
field.  The Web is now sufficiently prolific that the norm should be
for most of a session description to be on the WWW server.  If only a
single URL is allowed, this tends to encourage this.  If we allow
multiple URLs then people will probably continue the current method of
having long descriptions.

As the number of announced sessions increases, the proportion of
sessions people want to see much information about decreases, and the
more you want SDP sessions to convey only essential information.  If
you're going to the effort to put a multicast together, then surely
you should be prepared to put together a few lines of description on
the Web which can easily then link to other relevant information?

Mark

---

From: Bill Fenner <[email-masked]>
Date: Wed, 10 May 1995 10:33:05 PDT

In message <[email-masked]> you write:
>If only a

I'm not so sure that I believe in social engineering by protocol design.  I 
think that if the protocol doesn't let the user do what they want (i.e. put in 
multiple URL's), then they will *make* it do what they want, (i.e. by putting 
them in the description field).

Them darned users, they's slippery folks...

  Bill