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Subject: discussion of the Creative Commons Metadata work

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  • From: Mike Linksvayer <ml AT creativecommons.org>
  • To: discussion of the Creative Commons Metadata work <cc-metadata AT lists.ibiblio.org>
  • Subject: Re: UUID/GUID
  • Date: Sun, 21 Mar 2004 18:39:19 -0800

Alexander Genaud wrote:
As per the 'semantic web', I've often wondered if hypertext
documents wouldn't be better identified and addressed using a
universally unique ID (UUID/GUID) rather than an URL.

URLs are universally unique identifiers that have the benefit of being decentralized.

It should be noted that there is a massive amount of redundancy
on the net by related sites as well as search engines and the
like. Certainly, this is what Creative Commons is doing with
related documents.

?

One could imagine a document referencing sources (or previous
versions) by an ID. If the referenced material were to change
location (which occurs often), the reference is lost.

<a href="http://site.com/12345.html"; uuid"12345.html" />

&lt;a href="http://site.com/12345.html"; uuid"12345.html" /&gt;>

What resolves the UUID? You have to trust that the resolver will be around longer than the original publisher, and that the resolver can deliver the referenced content. Otherwise you're no better off than with using PURL or similar, which can point you to a current URL if someone has bothered to keep PURL informed.

OTOH if your identifier is content derived (e.g., content hash) rather than just a big random number you don't need a resolver, and maybe there will be some means of finding the content (a P2P query now). It would be interesting to see <a>, <img> and the like support multiple URIs, some of which could be URNs. <http://magnet-uri.sf.net> is a workaround that doesn't need additions to XHTML, but does need browser support to be useful for normal links and images -- magnet links are currently used mostly to bridge the web and P2P. Another partial solution could involve additional HTTP headers. Perhaps the only practice that would cause zero breakage now and hold out some hope of being useful in the future would be to publish link metadata, e.g.,

<a href="http://creativecommons.org/";>Creative Commons Rulez</a>

(snippet from elsewhere)

<rdf:Description rdf:about="http://creativecommons.org/";>
<dc:identifier>urn:sha1:7FCKK7IMKPNWUVA2SCJA53R2WHUPNJ5K</dc:identifier>
<dc:identifier>other urn</dc:identifier>
<dc:identifier>yet another urn</dc:identifier>
</rdf:Description>

And see <http://www.w3.org/Provider/Style/URI.html>.

Alexander wrote later:
> Thank you. URN is precisely what I was rambling about. Is it
> generally utalize on the open internet. For example, can I
> search for a document (via google perhaps) by its URN?

Depending what sort of URN you're looking for via Google, you might find a Bitzi metadata record (which will likely give you additional content identifiers. AFAIK P2P is the only means of obtaining content via certain URNs at this point.

> Perhaps there is an advantage to using an URN in or alongside
> the CC license metatags. Software could easily keep track of
> bibliographic reference for an author and, with the help of a
> good query, do such things as find the root source of specific
> data, or what material references another document.
>
> example URN:
>
> urn:cc:FFFF:md5:5307d294b6ccd9854f2deed8c1628b72
>
> where cc:FFFF might represent an id generated by CC.
> md5:5307d294b6ccd9854f2deed8c1628b72
> might be a hash digest of the document.

Recording derivation seems like a problem separable from identifiers, and is addressed by dc:source.

--
Mike Linksvayer
http://creativecommons.org/learn/aboutus/people#21



  • Oops, Evan Prodromou, 03/19/2004
    • UUID/GUID, Alexander Genaud, 03/19/2004
      • Re: UUID/GUID, Chris Snyder, 03/19/2004
        • URN, Alexander Genaud, 03/19/2004
      • Re: UUID/GUID, Mike Linksvayer, 03/21/2004

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