My feeling is that UK LOM Core has a major problem with the way it
mandates so many elements.
I think this desire to mandate elements comes from a world view which
assumes that metadata is always passed around in discrete and complete
chunks called records - and that therefore it is always possible to say
whether any particular chunk meets some rules that determine whether it is
valid as a record or not.
More open views, like that of RDF for example, don't take such a fixed
view about whether something is a 'record' or not. They take the view
that sets of metadata properties (elements) can be pulled together from
anywhere and combined in various ways to meet a particular need.
Therefore, the notion of something being mandatory or not simply doesn't
arise - if you are missing an element it may just be because you haven't
yet found the bit of metadata that provides that information yet.
Consider the following scenario...
1) An RDN hub provides the core descriptiove elements about a resource
(title, description, subject keywords, etc.).
2) An LTSN centre provides some e-learning metadata about the same
resource (level, semantic density, learning time, etc.).
3) A third-party service allows end-users to provide annotations about the
same resource.
Each of these services makes their metadata available using the LOM XML
binding. Each follows the cataloguing guidelines in the UK LOM Core for
the elements that they control.
Taken together, the three parts provide a full, UK LOM Core compliant
record. But individually, the metadata exposed by each service is not
compliant because it doesn't contain the full set of mandatory elements.
I think that it would be more helpful to allow these services to claim
compliance with the UK LOM Core, even though they each only contain
partial information. It somehow feels wrong, or at least I don't
understand what we achieve, by saying that the individual services are not
complient.
The other argument against making so many elements mandatory is that for
all elements (with the possible exceptions of the identifiers) there will
be some scenarios in which the element has no valid value. In such cases,
the only course of action is to provide the element with a null value? I
assume that a null value is legal(?) but doing this seems, to me, to
completely undermine what is being attempted by trying to mandate
particular elements. Why is an empty value OK but a missing element is
not?
In conclusion, I think that the only elements in UK LOM Core that are
mandatory should be
1.1 general.identifier
and
3.1 metaMetadata.identifier
and even those I'd be prepared to be argued out of! Everything else
should be highly desirable, desirable or optional. This would allow
applications to make sensible decisions about which elements they expose
or not.
In summary, conformance with UK LOM Core should tell you more about how
particular elements and values have been used than about which set of
elements to expect in a record.
Thoughts?
Andy
--
Distributed Systems, UKOLN, University of Bath, Bath, BA2 7AY, UK
http://www.ukoln.ac.uk/ukoln/staff/a.powell +44 1225 383933
Resource Discovery Network http://www.rdn.ac.uk/
ECDL 2004, Bath, UK - 12-17 Sept 2004 - http://www.ecdl2004.org/
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