Re: I-D submission "Requirements on TV Broadcast URIs"

From: Gomer Thomas (gomer@lgerca.com)
Date: Wed, Nov 18 1998


Message-ID: <3652E53E.4F5ABA11@lgerca.com>
Date: Wed, 18 Nov 1998 10:18:22 -0500
From: Gomer Thomas <gomer@lgerca.com>
To: www-tv <www-tv@w3.org>
Subject: Re: I-D submission "Requirements on TV Broadcast URIs"

I agree with Craig's point on compatibility. The term "compatible with" is very
ambiguous. Moreover, to my knowledge the only standardization body which has
already adopted a URI scheme is DAVIC. There have been several proposals to
ATSC, but none have gone anywhere.

(At the same time, I believe the scheme which Craig and I have in mind is
"compatible with" the DAVIC scheme in a very useful sense, namely a "tv:" URI
can be translated into a "dvb:" URI in the context of a DVB receiver when
needed.)

A requirement to support relative referencing is basically a requirement to use
the <hier_part> syntax for an absolute URI, as described in section 5 of RFC
2396. This seems to me like a reasonable requirement.

As for the "exception" which refers to the semantics of "host": the use of the
term "host" is probably misleading in the first place. RFC 2396 uses the term
"authority" instead of "host" in the "generic URI" syntax. In the DTV context I
believe it will typically resolve to a transport stream, channel, or event.
Whether one can view it as representing the "source" of a transport stream
depends on what one means by "source". For the purposes of these requirements,
that doesn't seem to me to be important. The key point is that it is not
necessarily an Internet server, and in fact usually is not. Since this
"exceptions" section is presumably not normative in any case, there is not much
point in getting bogged down in fine points here.


I see no reason to include this point.  None of the ATSC, DVB, or

Craig A. Finseth wrote:

>         ...
>    o  The URI scheme must be compatible with solutions already adopted
>       in standardisation bodies such as ATSC, DVB, and DAVIC.
>         ...
>
> I see no reason to include this point.  None of the ATSC, DVB, or
> DAVIC proposed schemes meet the other requirements.  Thus, requiring
> compatability with something that does not meet the requirements is
> confusing at best.
>
>    o  The URI scheme should support relative referencing such that
>       a TV-program with all its associated resources can be referenced
>       against a common base, which is the TV Broadcast URI of that
>       aggregate.
>
> I would put this in the category of "nice, but if it doesn't work out,
> not a big deal."
>
>    5. Exceptions in TV Broadcast URIs
>
>    TV Broadcast differs from the conventional Internet in several ways.
>    The TV Broadcast URI scheme is affected by that in the following aspects:
>
>    o  The host is not necessarily a server identifyable through an
>                                            identifiable
>       IP-address. For instance, the 'host' is a transport stream.
> Well, the "host" is the _source_ of a transport stream...
>         ...
>
> Craig



--
Gomer Thomas
LGERCA, Inc.
40 Washington Road
Princeton Junction, NJ 08550
phone: 609-716-3513
fax: 609-716-3503