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Tim Bray wrote:
>
> Ronald Bourret wrote:
>
> > That is, it may be possible to process a
> > document based solely on the information in various RDDL documents, but
> > this is unlikely to be true in general.
>
> I haven't made up my mind whether RDDL is a good enough idea to
> be worth investing more time in either by way of development
> or standardization; at least it's been a useful thought experiment.
>
> That being said, could you outline some scenarios where RDDL would
> fail be sufficient for reasons of insufficient generality or
> whatever? -Tim
The problem is that a RDDL document can't know the context in which the
elements it describes are used. This is a problem on the human readable
end of things, but not enough so to make RDDL documents useless. For
example, a RDDL document describing a namespace for elements for
people's names can tell me that such and such an element is a last name,
but it can't tell me whose last name, since that depends on the context
in which the name is used.
At the machine level, the problem is even worse. For example, the
aforementioned RDDL document might contain a stylesheet that converts
name elements to HTML. But how useful is this? I probably want to
display a name differently in a resume than in a list of employees.
(Note that the context is even greater than just the containing document
-- it also includes an application. One application might print resumes
as such while another might list job applications and languages spoken.)
In thinking about using the machine readable parts of a RDDL document at
run time, I think schemas are very useful if they can be used in a
modular fashion. Stylesheets are marginally useful. And code is close to
useless. On the other hand, all of these would be quite useful at design
time. For example, a human using a programming framework could pick
through a library of modules that can process names in the hopes that
one will meet their needs.
So while I think RDDL does have a place, it is mostly at the level of
educating people and making resources known, rather than providing
processing information. In rereading your document, it seems this might
also be your opinion, as your only mention of document processing is
point 8:
Content-negotiation is not a sufficiently powerful tool for
selecting definitive-material resources.
-- Ron
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