Hi Gregor,
thanks, this kind of input is exactly why I put these mails on the public
list :)
2013/1/30 Gregor Hagedorn <g.m.hagedorn(a)gmail.com>
Some of our insights into the SMW RDF export (which we
found to be
difficult to configure and use):
1. Probably most relevant: total lack of support for xml:lang, which would
have been essential to our purposes.
Wikidata should be planned with support for language in mind.
SMW does have support for xml:lang, but only for the one language the wiki
is in. SMW was not intended for multilingual support.
In Wikidata we have a stronger focus on this, and will use xml:lang, but
completely transparent to the user.
So, agreed.
2. We also found that we had serious problems with managing structure,
e.g. record and subobject. Due to the need to obtain this information
recursively by repeated calls, and because there is no control on the URI
created for these calls, some easy solutions like applying clean-up xslt
will not work. This may not be relevant for wikidata.
This should indeed not be relevant, agreed. (I wouldn't use XSLT here, by
the way, but maybe a SPARQL construct query).
3. At first the lack of variable datatype (datatype is
fixed per property)
is acceptable. However, we found this a major problem with respect to the
forced distinction between datatype:wiki-page and datatype:global URI
properties. Essentially, SMW forces one to introduce for a semantic
property (e.g. dc:creator) two distinct dummy properties:
property:creator_page and property:creator_uri. Since in RDF export the
artificial distinction between pages and URIs disappears, it would be
desirable to merge them, but only one of them can be set to an imported
vocabulary.
I think this may be relevant to wikidata, where a similar distinction
between properties pointing to a local wikidata item and a global resource
exists.
Hmm... this really depends on how we deal with URIs to external entities in
Wikidata. To be honest, we have not decided that yet (or even thought much
about it). The assumption was always more like "we have everything as an
item", and the idea of external items has not really made it to the list
yet.
Without that, this is not relevant for Wikidata. But especially for
Wikibase installations that are not Wikidata this might be a very valid
point. I have to think more through it.
Gregor
(PS: If any of the problems above in reality does not exist in SMW and we
simply overlooked the solution, I am very happy for corrections, of course!)
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