University of Glasgow

Roderic Page

OK, a bit of hyperbole in the morning. One of the goals of RDF is to
create the Semantic Web, an interwoven network of data seamlessly linked
by shared identifiers and shared vocabularies. Everyone uses the same
identifiers for the same things, and when they describe these things
they use the same terms. Simples.  
  
Of course, the reality is somewhat different. Typically people don\'t
reuse identifiers, and there are usually several competing vocabularies
we can chose from. To give a concrete example, consider two RDF
documents describing the same article, one provided by CiNii, the other
by CrossRef. The article is:  
  

> Astuti, D., Azuma, N., Suzuki, H., & Higashi, S. (2006). Phylogenetic
> Relationships Within Parrots (Psittacidae) Inferred from Mitochondrial
> Cytochrome-b Gene Sequences(Phylogeny). Zoological science, 23(2),
> 191-198.
> [doi:10.2108/zsj.23.191](http://dx.doi.org/10.2108/zsj.23.191)

  
You can get RDF for a CiNii record by appending \".rdf\" to the URL for
the article, in this case <http://ci.nii.ac.jp/naid/130000017049>. For
CrossRef you need a Linked Data compliant client, or you can do
something like this:  
  

``` {style="font-size:10px;border:1px solid rgb(192,192,192);background-color:rgb(240,240,240);"}
curl -D - -L -H "Accept: application/rdf+xml" "http://dx.doi.org/10.2108/zsj.23.191"
```

You can view the RDF from these two sources
[here](http://dl.dropbox.com/u/639486/rdf/130000017049.rdf) and
[here](http://dl.dropbox.com/u/639486/rdf/doi.rdf).  
  
**No shared identifiers**  
The two RDF documents have no shared identifiers, or at least, any
identifiers they do share aren\'t described in a way that is easily
discovered. The CrossRef record knows nothing about the CiNii record,
but the CiNii document includes this statement:  
  

``` {style="font-size:10px;border:1px solid rgb(192,192,192);background-color:rgb(240,240,240);"}

```

So, CiNii knows about the DOI, but this doesn\'t help much as the
CrossRef document has the URI \"http://dx.doi.org/10.2108/zsj.23.191\",
so we don\'t have an explicit statement that the two documents refer to
the same article.  
  
The other shared identifier the documents could share is the ISSN for
the journal (0289-0003), but CiNii writes this without the \"-\", and
uses the PRISM term \"prism:issn\", so we have:  
  

``` {style="font-size:10px;border:1px solid rgb(192,192,192);background-color:rgb(240,240,240);"}
02890003
```

  
whereas CrossRef writes the ISSN like this:  
  

``` {style="font-size:10px;border:1px solid rgb(192,192,192);background-color:rgb(240,240,240);"}

0289-0003
```

  
Unless we have a linked data client that normalises ISSNs before it does
a SPARQL query we will miss the fact that these two articles are in the
same journal.  
  
**Inconsistent vocabularies**  
Both CiNii use the PRISM vocabulary to describe the article, but they
use different versions. CrossRef uses
\"http://prismstandard.org/namespaces/basic/2.1/\" whereas CiNii uses
\"http://prismstandard.org/namespaces/basic/2.0/\". Version 2.1 versus
version 2.0 is a minor difference, but the URIs are different and hence
they are different vocabularies (having version numbers in vocabulary
URIs is asking for trouble). Hence, even if CiNii and CrossRef wrote
ISSNs in the same way, we\'d still not be able to assert that the
articles come from the same journal.  
**Inconsistent use of vocabularies**  
Both CiNii use FOAF for author names, but they write the names
differently:  
  

``` {style="font-size:10px;border:1px solid rgb(192,192,192);background-color:rgb(240,240,240);"}
Suzuki Hitoshi
```

``` {style="font-size:10px;border:1px solid rgb(192,192,192);background-color:rgb(240,240,240);"}
Hitoshi Suzuki
```

  
So, another missed opportunity to link the documents. One could argue
this would be solved if we had consistent identifiers for authors, but
we don\'t. In this case CiNii have their own local identifiers (e.g.
<http://ci.nii.ac.jp/nrid/1000040179239>), and CrossRef has a rather
hideous looking
[Skolemisation](http://www.w3.org/2011/rdf-wg/wiki/Skolemisation):
<http://id.crossref.org/contributor/hitoshi-suzuki-2gypi8bnqk7yy>.  
  
In summary, it\'s a mess. Both CiNii and CrossRef organisations are
whose core business is bibliographic metadata. It\'s great that both are
serving RDF, but if we think this is anything more than providing
metadata in a useful format I think we may be deceiving ourselves.  
  


OK, a bit of hyperbole in the morning. One of the goals of RDF is to create the Semantic Web, an interwoven network of data seamlessly linked by shared identifiers and shared vocabularies. Everyone uses the same identifiers for the same things, and when they describe these things they use the same terms. Simples.Of course, the reality is somewhat different.

Publicaciones de Rogue Scholar

Linked data that isn't: the failings of RDF