In writer Marshall McLuhan's global village, a lot of kiosks and corner stores of creative output are dwarfed by the megalithic big box stores. Luckily, the same media that have globalized the reach of creative output also provide the tools to even the pitch on which producers of all sizes play. From independent filmmakers, musicians, and authors to the open source and Weblog communities, there has long been a push to advertise and distribute material on the Internet, and usually at much lower cost and less restrictive terms than more commercial content. This push has had aspects of politics, economics, and technical problem-solving, raising questions like the following:

• Can the wider spread of less restricted content put pressure on policymakers and big media companies to lessen restrictions on consumers' rights? Would this pressure increase if the variety of rights and restrictions on content were better communicated to consumers?
• Would independent producers be able to reach a wider audience, and thus earn a better living, if they had a better way to advertise their output and perhaps attract business by declaring less restrictive licenses?
• Will a technical network of machine-readable metadata help to improve the tools and communications channels between producers and consumers of content?

To answer these questions and others, a coalition of independent content producers, technologists, and lawyers banded together last year under the umbrella of the Creative Commons project (see Resources) to produce technology for machine-readable copyright licenses. This project employs RDF to describe the various rights and restrictions for a particular license using a vocabulary that was developed by the project's legal wizards.

This enabling technology is intended to make it easy for people to find content to share and collaborate on in a peer-to-peer environment. As Creative Commons folk like to say, it allows producers and consumers to skip the intermediaries. In the common scenario, my favorite indie band signs on to a small music label, which then signs a distribution deal with a large label, which then distributes CDs to a large music retailer, which I then visit to make the purchase. I pay a price premium for each layer in that intermediary chain, and I am forced to swallow usage terms that are set by very expensive lawyers who do not have my interests in mind, nor usually those of the original producer. In the Creative Commons world, I go online to see the sort of music I like and who may be producing music that I can enjoy on what I consider fair terms. I can then make my commerce directly with the producer. In this article, I shall introduce the data formats used by Creative Commons.

The code behind copyright

Let's say you're a playwright, and you've just completed a masterpiece. You want to post it on your Web site. You want people to be able to perform your play on their local campus. You want to allow your peers in Kobe and California to collaborate on a Kabuki version of your masterpiece. You do not, however, want XBC MegaMedia Inc. to simply rip off your work and produce a primetime version of it, without crediting you, and restrict the rights of their own viewers regarding the derivative version of your creation. You have neither the time nor the money for lawyers who would craft a license that walks the fine line between opening up your work to collaboration and use by your peers, and protecting you from abuse.

Creative Commons has a solution. You can go to their Web page and use a set of mercifully simple criteria to determine how you'd like to license your work. You will probably find, in the case of your masterpiece play, that what you have in mind is the Creative Commons Attribution-ShareAlike license. You can view the full legalese of this license, and also choose from the several easy ways to mark your work with the license. Since you're posting it on the Web, you can get the HTML snippet to include in your Web page with the play in order to assert the license. Listing 1 is an example of the HTML for the Attribution-ShareAlike license.

<!-- Creative Commons License -->
<a href="http://creativecommons.org/licenses/by-sa/1.0/">
<img alt="Creative Commons License" border="0" 
src="http://creativecommons.org/images/public/somerights.gif" /></a><br />
This work is licensed under a
<a href="http://creativecommons.org/licenses/by-sa/1.0/">Creative Commons License</a>.
<!-- /Creative Commons License -->

<!--

<rdf:RDF xmlns="http://web.resource.org/cc/"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<Work rdf:about="">
<license rdf:resource="http://creativecommons.org/licenses/by-sa/1.0/" />
</Work>

<License rdf:about="http://creativecommons.org/licenses/by-sa/1.0/">
   <requires rdf:resource="http://web.resource.org/cc/Attribution" />
   <requires rdf:resource="http://web.resource.org/cc/ShareAlike" />
   <permits rdf:resource="http://web.resource.org/cc/Reproduction" />
   <permits rdf:resource="http://web.resource.org/cc/Distribution" />
   <permits rdf:resource="http://web.resource.org/cc/DerivativeWorks" />
   <requires rdf:resource="http://web.resource.org/cc/Notice" />
</License>

</rdf:RDF>

-->

Most of this is simply images and text that alert people of the licenses, but the part of most interest to this column (and thus highlighted in bold) is an embedded RDF document that provides a machine-readable description of the license. This is pretty straightforward RDF. The rdf:about="" attribute on the Work typed node indicates that the resource being described is the very document in which the RDF is embedded. The chosen license is then indicated by a reference to its URI. To keep an agent from having to chase down that URI to get details on the license, those details are provided in-line as well.

The vocabulary of the RDF is firmly grounded in the careful legal work behind Creative Commons, and as such may be among the best-defined RDF vocabularies out there. The predicates permits, requires, and prohibits (not used in Listing 1) indicate the level of restriction on each sort of usage, and the objects specify the sort of usage in question. For example, in simple prose, the above description of the license terms boils down to the following:

• Anyone, even commercial interests, may reproduce the work.
• Anyone, even commercial interests, may distribute the work.
• Anyone, even commercial interests, may produce derivative works.
• Those reproducing or distributing the work, or producing derivative works, must include attribution to the original author.
• Such users must offer the same licensing terms as the original license (share-alike).
• Such users must keep all legal notices intact from the original work.

Warning: I am not a lawyer, and the above is simply an informal gloss on the semantics behind the RDF vocabulary for the machine-readable license terms. If you want to be clear about the legal color of the license, consult the Attribution-ShareAlike license summary page (see Resources), which includes a link to the full legalese.

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Technical assessment

The biggest technical problem with the mechanism of embedding the RDF in comments within the HTML page is that it is a pretty adventurous layering of technologies. First, as Kendall Clark points out in an article on this approach (see Resources), it is mixing machine-readable information (RDF) rather directly into a human-readable format (HTML), and, in fact, into a portion of the format (comments) that is especially unsuited to machine-readable bits. The practice of using comments to bury machine-readable code in HTML is an old one (the script tag is the classic example), but this doesn't mean it's either natural or ideal. One alternative approach that's been suggested is to use HTML meta tags to refer to a Creative Commons description in standalone RDF.

For users of the Creative Commons technology, it may also be useful to provide machine-readable details on authorship, relevant dates, subject matter, and so on. The Creative Commons format already provides a useful template for this: Using the Dublin Core vocabulary, one can expand the Work typed node in the RDF as shown in Listing 2.

<Work rdf:about="" xmlns:dc="http://purl.org/dc/elements/1.1/">
  <license
    rdf:resource="http://creativecommons.org/licenses/by-sa/1.0/" />
  <dc:title>Bigfoot the King</dc:title>
  <dc:description>
    An original play dealing with the ironies of fate
  </dc:description>
  <dc:creator>Erasmus Jones</dc:creator>
  <dc:subject>Fate</dc:subject>
  <dc:subject>Justice</dc:subject>
  <dc:subject>Royal weirdos</dc:subject>
  <dc:format>application/xhtml+xml</dc:format>
</Work>

This is convenient because you are already using RDF/XML to describe the document (in licensing terms), so there is no harm in extending it to describe other aspects of its metadata. Then again, I've always been a strong advocate for not forcing in RDF/XML where plain XML will do, and if your content is in XHTML, then the other metadata could also be provided using XHTML meta tags, and a smart processor could process it into RDF automatically. Perhaps a way will also emerge to express Creative Commons more directly in XHTML. Again, RDF/XML is but one representation of RDF, and Creative Commons will gain the benefits of the RDF model regardless of which representation is used.

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Wrap up

Creative Commons is perhaps the most impressive embodiment of the ideas and potential behind RDF and related technologies. The vocabulary is anchored in authority developed by a team of lawyers -- and lawyers, of course, are the profession most associated with nailing down semantics. More important, the project is showing remarkable growth and providing clear benefits to a very broad variety of artists, developers, lawyers, and consumers. Most of these beneficiaries do not care one whit about metadata and information representation. They just want to know how they can share creative works from their peers, and how they can make their own work available in return. It's rare that technology, policy, and business can find such a concordance, and it's great to see XML metadata technologies providing the engine for the expansion of the commons.

Resources

• Participate in the discussion forum.
  
  
• Visit the Creative Commons home page for information on the policy and technical aspects of the project, and to select a license for your own work. The Creative Commons Weblog has frequently updated news on the project and community. If you want to be clear about the legal color of the license, consult the Attribution-ShareAlike license summary page, which includes a link to the full legalese.
  
  
• Read "Creative Comments: On the Uses and Abuses of Markup," by Kendall Clark, for a discussion of the manner in which the Creative Commons chose to embed RDF in HTML. Another good article is "Returning Creativity to the Commons" by Richard Koman.
  
  
• For more on the writings of Marshal McLuhan, visit his official Web site.
  
  
• Want more on the discussion about the desirability and good techniques for embedding RDF in HTML? See this summary for more information. See also this discussion of the issue by the W3C Technical Architecture Group.
  
  
• Check out Thinking XML's previous columns.
  
  
• Find more XML resources on the developerWorks XML zone.
  
  
• Get the IBM WebSphere Studio suite of tools that automate XML development, both in Java and in other languages. It is closely integrated with the WebSphere Application Server, but can also be used with other J2EE servers.
  
  
• Find out how you can become an IBM Certified Developer in XML and related technologies.
  
  

About the author

Uche Ogbuji is a consultant and co-founder of Fourthought Inc., a software vendor and consultancy specializing in XML solutions for enterprise knowledge management. Fourthought develops 4Suite, an open source platform for XML, RDF, and knowledge-management applications. Mr. Ogbuji is a computer engineer and writer born in Nigeria, living and working in Boulder, Colorado, USA. You can contact him at uche@ogbuji.net.

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Table of contents

• The code behind copyright
• Technical assessment
• Wrap up
• Resources
• About the author
• Comments