Andy Powell wrote:
> You are basing this on a 'dumb-down rule' that hasn't been published
> ouside of the DC-Datamodel WG and that probably needs more work. For
> example, the rule could say that DC engines throw away the rdf:value
> if the dcq:creatorType isn't a recognised DC Type.
True. But this alternative rule have other serious problems.
> This whole area needs more work.
Very, very true.
>> Now, let us assume that somebody think that the following is a great
>> way to tell the world about the birthdate of the creator of the
>> resource:
>>
>> <?xml version="1.0"?>
>> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>> xmlns:dc="http://purl.org/dc/elements/1.0/"
>> xmlns:dcq="http://purl.org/dc/qualifiers/1.0/">
>> <rdf:Description about="http://my page/">
>> <dc:creator>
>> <rdf:Description>
>> <rdf:value> 1953-07-13 </rdf:value>
>> <dcq:creatorType
>> rdf:resource="http://my schema/creatortype/PersonalName/DateofBirth#" />
>> </rdf:Description>
>> </dc:creator>
>> </rdf:Description>
>> </rdf:RDF>
>>
>>
>> Oh yes, this is valid Qualified Dublin Core. If we accept Qualified
>> Dublin Core, there is nothing (repeat nothing) to stop people from
>> doing this.
>>
>> Will they do this?
>> You bet!
> This example may be valid syntax for qualified DC. But it doesn't mean
> anything, because DateofBirth doesn't refine the semantics of the
> dc:creator property in any meaningful way. (In DC Datamodel terms,
> DateofBirth is a value component not an element qualifier).
I agree with you completely. Yes, it is meaningless.
But because it _also_ is syntactically valid qualified DC, a DC engine
will have to deal with in one way or another. Computers are not very
adept at understanding that a particular datum is meaningless.
As the old saying goes: Garbage In = Garbage Out.
> So, if someone chooses to do this, they will have metadata that doesn't
> mean what it says and that doesn't interoperate with anyone else (or that
> only interoperates with people who have a shared local agreement to
> mis-use the model). So what! There are umpteen ways in which people
> can create metadata that doesn't interoperate? If people want to interoperate
> then they will have to create metadata according to rules - and the rules
> will include syntax rules and cataloguing rules.
"Will" is operative word here. If the last sentence had been
phrased in the present tense, I would have been a lot less
concerned.
We have in front of us, and are commenting on, a draft of [dchtml]
that is going to become an RFC published by IETF.
When a RFC is published, you can expect (and hope for) people to
start using it. Maybe a lot of people. The way the section about
qualified Dublin Core is phrased in the May 18 [dchtml] draft, we
can only expect that these people will go ahead and invent all sorts
of qualifiers _in_good_faith_. You can expect implementers of
DC engines invent all sort of different rules for dealing with
these _in_good_faith_.
Maybe we will get around to creating these rules at some point or
other. When we do, we shall have on our hands (or rather -- on
the Internet) a potentially huge installed base of qualified DC
metadata, and maybe a dozen or so DC metadata engines in operation,
created in good faith based upon the text of this RFC. Some
portion of this installed base will with a fairly high probability
violate the rules which we have not written yet.
One doesn't need much imagination too see what the existence of
such an installed base will do to the general usefulness of the
Dublin Core as a tool for resource discovery on the Internet.
--
- gisle hannemyr ( [log in to unmask] - http://home.sol.no/home/gisle/ )
------------------------------------------------------------------------
"Use the Source, Luke. Use the Source." -- apologies to Obi-Wan Kenobi
------------------------------------------------------------------------
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|