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cc-devel - Re: [cc-devel] CC 1.5 and embedding RDF

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Subject: Developer discussion for Creative Commons technology and tools

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  • From: Nathan Yergler <nathan AT creativecommons.org>
  • To: Wendy Bossons <wbossons AT mit.edu>
  • Cc: cc-devel AT lists.ibiblio.org
  • Subject: Re: [cc-devel] CC 1.5 and embedding RDF
  • Date: Mon, 7 Dec 2009 14:07:33 -0800

The RDF-XML from the web services (that includes the Work assertion)
represents the same information as rel="license"; both associate a
license with a particular work. The RDF-XML is obviously more
verbose, as it includes the description of the license as well. A
parser could dereference the license URI and retrieve the same
information if they started with just the license URI.

So the two are really equivalent, just different encodings (one in
XML, one in XHTML).

Note that before RDFa (RDF in XHTML) was available we recommended
including the RDF-XML chunk in an HTML comment. This has many
problems, not the least of which is that it's opaque to parsers and
was never widely adopted. It's also frequently crippled by CMS
systems trying to be helpful by turning the angle brackets into
entities.

Don't worry about asking questions; that's what we're here for :).

Nathan


On Mon, Dec 7, 2009 at 12:19 PM, Wendy Bossons <wbossons AT mit.edu> wrote:
> I apologize in advance for all of the questions, but I am still learning . .
> . what is the use case for the rdf in the CC issue response? I have to make
> a case for changing the data we store, and I can't make it without
> understanding when the embedded rdf is required -- from reading the document
> that was written with Hal Abelson (ccREL: The Creative Commons Rights
> Expression Language), I gather that it would be for tools that make or read
> CC protected resources. Is that correct? So, there may be some unforeseen
> need to use the rdf with respect to tools, other than the web application?
> Example:
> <rdf>
>
> <rdf:RDF xmlns="http://creativecommons.org/ns#";
>
> xmlns:dc="http://purl.org/dc/elements/1.1/";
>
> xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
>
> xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#";>
>
>   <Work rdf:about="">
>
>    <license
>
> rdf:resource="http://creativecommons.org/licenses/by/3.0/us/"/>
>
>   </Work>
>
>   <License rdf:about="http://creativecommons.org/licenses/by/3.0/us/";>
>
>    <permits rdf:resource="http://creativecommons.org/ns#Reproduction"/>
>
>    <permits rdf:resource="http://creativecommons.org/ns#Distribution"/>
>
>    <requires rdf:resource="http://creativecommons.org/ns#Notice"/>
>
>    <requires rdf:resource="http://creativecommons.org/ns#Attribution"/>
>
>    <permits
>
> rdf:resource="http://creativecommons.org/ns#DerivativeWorks"/>
>
>   </License>
>
>  </rdf:RDF>
>
> </rdf>
>
> ...\Wendy
> Wendy Bossons
> Web Developer
> Contact Information:
> wbossons AT mit.edu
> 617-253-0770
>
>
>
>
>
> On Dec 7, 2009, at 1:44 PM, Nathan Yergler wrote:
>
> Right, although in the second case, you don't even need the xmlns:cc
> attribute.
>
> Nathan
>
>
> On Mon, Dec 7, 2009 at 8:38 AM, Wendy Bossons <wbossons AT mit.edu> wrote:
>
> So then either of the following are correct (first example is from the given
>
> w3 page), but the unprefixed form is safer in the sense that it's more
>
> likely to be understood by a wide range of search engines . . .
>
> <a xmlns:cc="http://creativecommons.org/ns#";
>
>  rel="cc:license"
>
>  href="http://creativecommons.org/licenses/by-nc-nd/3.0/";>
>
>  Creative Commons License
>
> </a>
>
> or
>
> <a xmlns:cc="http://creativecommons.org/ns#";
>
>  rel="license"
>
>  href="http://creativecommons.org/licenses/by-nc-nd/3.0/";>
>
>  Creative Commons License
>
> </a>
>
>
>
> Wendy Bossons
>
> Web Developer
>
> Contact Information:
>
> wbossons AT mit.edu
>
> 617-253-0770
>
>
>
>
>
> On Dec 7, 2009, at 10:28 AM, Nathan Yergler wrote:
>
> license is one of the reserved values in RDFa, as it's defined in the
>
> XHTML namespace; see http://www.w3.org/TR/rdfa-syntax/#relValues for a
>
> list of these values.  It's implicit that license is in the XHTML
>
> namespace, and any conforming RDFa processor will return a fully
>
> qualified URI in that namespace.
>
> You could do cc:license, but these days it's declared to be the same
>
> of xhtml:license.  Additionally, it appears that some search engines
>
> do not use conforming processors to index CC licensed content, instead
>
> looking for rel="license", so using a different namespace will impact
>
> how they index your content.
>
> Nathan
>
>
> On Mon, Dec 7, 2009 at 7:21 AM, Wendy Bossons <wbossons AT mit.edu> wrote:
>
> Why is the metainformation attribute, rel, never prefixed when it references
>
> "license"?
>
> Example:
>
> <a rel="license"
>
> href="http://creativecommons.org/licenses/by/3.0/us/";>......</a>
>
> Would it be incorrect to rephrase the above as:
>
> <a rel="cc:license" xmlns:cc="http://creativecommons.org/ns#";
>
> href="http://creativecommons.org/licenses/....";>.......</a>
>
> The reason I ask is the CC LIcense searchable as metadata within the
>
> application I'm working on. If it is to do that, I believe the license
>
> metadata should follow the same pattern as other metadata, such as
>
> <span xmlns:dc="http://purl.org/dc/...."; href="http://purl.org/dc/dmcitype/";
>
> rel="dc:type">work</span>
>
>
> ..\Wendy
>
>
> Wendy Bossons
>
> Web Developer
>
> Contact Information:
>
> wbossons AT mit.edu
>
> 617-253-0770
>
>
>
>
>
>
> On Dec 3, 2009, at 1:38 PM, Nathan Yergler wrote:
>
> Hi Wendy,
>
> The two blocks have (had) slightly different purposes; the first one
>
> describes a work with a particular license.  The latter only describes
>
> the license.
>
> That said, we no longer recommend embedding either in HTML pages.  We
>
> previously recommended embedding the former block in an HTML comment.
>
> While this approach had advantages over other available approaches
>
> when we developed it, it still has lots of problems, including over
>
> verbosity, invisibility to many parsers, and lack of standards
>
> compliance.  We're now recommending the use of RDFa to describe the
>
> license of a page.  See
>
> http://creativecommons.org/choose/results-one?license-code=by for an
>
> example of the HTML+RDFa needed to describe the license of a work, and
>
> http://wiki.creativecommons.org/ccREL for more details.
>
> Let me know if you have any questions.
>
> Nathan
>
>
> On Mon, Nov 30, 2009 at 2:51 PM, Wendy Bossons <wbossons AT mit.edu> wrote:
>
> What is the current recommendation on using the rdf that is returned by
>
> the
>
> CC issue call?
>
> For example, there are two rdf blocks in the response. Is one for
>
> backward
>
> compatibility? How do you recommend using the response, e.g. if embedding
>
> the rdf in the page, should one or both of the rdf blocks be used?
>
> Example from response document:
>
> ...
>
> <rdf>
>
>  <rdf:RDF xmlns="http://creativecommons.org/ns#";
>
> xmlns:dc="http://purl.org/dc/elements/1.1/";
>
> xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
>
> xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#";>
>
>   <Work rdf:about="">
>
>    <license
>
> rdf:resource="http://creativecommons.org/licenses/by/3.0/us/"/>
>
>   </Work>
>
>   <License rdf:about="http://creativecommons.org/licenses/by/3.0/us/";>
>
>    <permits rdf:resource="http://creativecommons.org/ns#Reproduction"/>
>
>    <permits rdf:resource="http://creativecommons.org/ns#Distribution"/>
>
>    <requires rdf:resource="http://creativecommons.org/ns#Notice"/>
>
>    <requires rdf:resource="http://creativecommons.org/ns#Attribution"/>
>
>    <permits
>
> rdf:resource="http://creativecommons.org/ns#DerivativeWorks"/>
>
>   </License>
>
>  </rdf:RDF>
>
> </rdf>
>
> <licenserdf>
>
>  <rdf:RDF xmlns="http://creativecommons.org/ns#";
>
> xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";>
>
>  <License rdf:about="http://creativecommons.org/licenses/by/3.0/us/";>
>
>    <permits rdf:resource="http://creativecommons.org/ns#Reproduction"/>
>
>    <permits rdf:resource="http://creativecommons.org/ns#Distribution"/>
>
>    <requires rdf:resource="http://creativecommons.org/ns#Notice"/>
>
>    <requires rdf:resource="http://creativecommons.org/ns#Attribution"/>
>
>    <permits
>
> rdf:resource="http://creativecommons.org/ns#DerivativeWorks"/>
>
>  </License>
>
>  </rdf:RDF>
>
> </licenserdf>
>
> Wendy Bossons
>
> Web Developer
>
> Contact Information:
>
> wbossons AT mit.edu
>
> 617-253-0770
>
>
>
>
>
>
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>
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