http://norman.walsh.name/2009/09/22/RDFaForDocBook 12 30 2009-09-22T14:20:39+01:00 Norman Walsh 2009 Norman Walsh Adding RDFa to DocBook would make it possible to add a class of semantic annotations to DocBook without changing the schema. But is that a good idea? Samuel Johnson Knowledge is of two kinds. We know a subject ourselves, or we know where we can find information on it. When Bob DuCharme introduced the semantic web track at XML Summer School this morning, he mentioned briefly the idea of adding RDFa to vocabularies other than (X)HTML. In particular, he's investigated how to do it in DocBook. The DocBook TC gets periodic requests to add new inline elements and attributes for bits of metadata. Sometimes the requests are entirely legitimate, in the sense that they're clearly about technical documentation, but seem to apply to such a small audience that the TC is reluctant to add them to all of DocBook. With this in mind, the idea of adding RDFa has some appeal: we add a few new attributes and henceforth users will be able to add new bits of metadata without having to change the DocBook schema. But I'm not sure. First, lots of DocBook elements have more discrete semantics than HTML elements. We don't need to say <phrase property="dc:title">Beautiful Sunset</phrase> because we have citetitle. We don't need to say: <info> <bibliomisc> <phrase rel="mpc:editor" href="http://mypubco.com/empid/53234"/> </bibliomisc> </info> because we have <info> <editor role="mpc:editor"> <personname>Some Name</personname> <uri>http://mypubco.com/empid/53234</uri> </editor> </info> I'm not suggesting those are exactly the same, they're clearly not, but I'm comfortable that existing DocBook elements are sufficient for the task. (Yes, you'd need a DocBook-specific tool to extract the metadata, which is a disadvantage, but you probably want one anyway for the existing DocBook semantics.) Second, it would allow you to construct statements with conflicting or, at best, odd semantics: <section> <title property="dc:creator">Alice1</title> <para xml:id='p12'>This is from section 2.2.</para> </section> I can just about imagine a sense in which “Alice1” can be both the title of a section and the Dublin Core creator of the section, but it doesn't make a lot of sense. Third, Bob's example seems to suggest that it would encourage markup like this: <para about="/alice/posts/trouble_with_bob" xml:id='p15'> <phrase property="dc:title">The trouble with Bob2</phrase> <phrase property="dc:creator">Alice2</phrase> </para> which seems like a bad idea to me. On the other hand, some of the examples do seem useful for exactly the sort of thing I suggested motivated my interest: <bibliomisc property="mpc:lastScreenShotDate" content="2009-08-01T15:31:00"/> <bibliomisc property="mpc:softwareRelease" content="3.1"/> In fairness, Bob set out to recreate the triples from the original tutorial, so some of the markup choices were forced upon him. So I'm not sure.