Re: URN single or multiple variants (was: four-part harmony?)

Dirk Herr-Hoyman ([email protected])
Thu, 23 Sep 1993 08:21:20 -36803936 (CDT)

> These properties I've collectively called the variant specifier. Now to
> continue with the list of cautious premises.
>
> (13)To paraphrase Tim, given a URN you should be able to ask some server
> to return you one or more variant specifiers, one for each variant.
> You select the variant you want, and pass it off together with the
> URN when you need to lookup the corresponding URL.
>
> (17)The variant specifier is thus a thing that optionally accompanies
> a URN, at the same level in our UR* scheme of things.
>
> (18)We need a new member of the UR* family for variants. How about URV?
>
So, what you are saying is that

URN + URV = URL

and that a URL refers to a single instance of a document at a single
locatation.

Although there may be some use of a URV within hypertext (and other
links), I would think that the typical case would be to just use an
unadorned URN, since I wouldn't know which variant would be wanted until
retrieval time. It would seem that some sort of negotiation/protocol
would be useful here, even something as simple as what Gopher+ does
(return list of all variants/views). This would allow for smart clients
to do the negiotiation.

As long as the URV is extendable, this looks like a good idea. I would
opt for just 2 dimensions within the URV right now, location and format.

I also remember a proposal for a URM (modifier). Would this work for
the URV?

-- 
Dirk Herr-Hoyman                            | 
Internet Publishing Specialist              | 
Electronic Journal of Extension             | Follow your heart! 
  Project Coordinator                       | 
University of Wisconsin-Extension           | (to Florida...) 
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