Subject: RE: Update of RFC 2838, tv: URI

From: "Deventer, M.O. \(Oskar\) van" <[email-masked]>
Date: Tue, 22 Aug 2006 11:02:10 +0200

All,

Here are my responses on some of the comments received.

> the URI scheme hasn't been registered through IANA.
I do not know what happened with RFC 2838. Perhaps Dan Zigmond can tell.
Notice that there is no (central) registry for tv: URIs, as they are
deduced/derived from other information.

> tv: URI point to a web page
A tv: URI does not point to a web page. It points to a TV channel.

> Have the proponents of changing it talked to the original authors
We contacted Dan Zigmond. Notice that all of the original RFC 2838
authors have changed jobs.

> Liberate made set-top boxes, ... pretty tough to upgrade
Fortunately, there are no differences between RFC 2838 and our proposed
update in the American context. In the American context, RFC
2838-derived tv: URI's seem to match 1-on-1 with the website associated
with that TV channel. I haven't found any counter-example yet. It is
only in the European public-networks context that ambiguities occur,
which we propose to solve with an update.

> it's difficult to change the meaning of a URI scheme 
> once that meaning is encoded in widely deployed software.
Our proposed update will keep the semantics of the tv: URI unchanged. It
will even keep all American tv: URI's unchanged, as mentioned above.

> It sounds like you are looking for some sort of location and guide
service.
We are looking for a way to identify TV channels unambiguously for a
wide variety of use cases. The RFC 2838 tv: URI matches our needs.
However, we need an update to make this RFC also unambiguous in the
European context.

> CRID, described in RFC 4078
Crid's identify references to content, as its acronym says. I can use a
crid to make a reference to an episode of "Friends", to the whole
"Friends" series or to comedies in general. When people check my
electronic program guide, it is my responsibility to resolve a
particular crid to a locator. Notice that my crid that refers to an
episode of "Friends" is different from your crid referring to that same
episode, as your and my domain names are incorporated in our crids.
In summary, crids refer to content and are unsuited for the unambiguous
identification of TV channels. This is why RFC 2838 exists.

> if you clicked on a URI like tv:bbc.co.uk/bbcone, on a 
> sufficiently equipped and configured device, you would view
> that channel.
Yes, that is one of the use cases for RFC 2838 and its proposed update.

> you might have a pull-down menu that provided options
> about what to do with the tv: URI
Yes, that could be another use case.

> iCalendar to transmit this information? That way people can integrate
> what shows they want to watch with their personal calendars.
Yes, this is another relevant use case for tv: URI. That is, if the
TC-channel identification needs to be unambiguous and
understood/interpreted by a machine/application.

> the URI might be processed by a very different tool
> than a web browser
Indeed.

> [discussions on URI versus URL, identifier versus locator]
The tv: URI of RFC 2838 is an identifier, not a locator. It identifies
TV channels, independent of the way it is broadcast (ether, cable,
analog, digital, fast pigeon transport). The resolution of tv: URI's is
outside the scope of RFC 2838 and its proposed update.

> They don't depend on HTTP except for minting, 
> [which] is a one-time operation.
Correct.

Best regards,

Oskar

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