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   Re: [xml-dev] The task to be solved by RDDL. Re: [xml-dev] RDDL(was RE:

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At 10:58 AM +0100 1/19/02, Nicolas Lehuen wrote:

>-- namespace-centricity, limiting RDDL to describing namespace meta-data,
>whereas what we really need is to describe document meta-data (think of a
>DOCTYPE declaration but not limited to DTDs).

The  you need something other than RDDL. This is not what RDDL was 
meant to do, nor did RDDL ever claim to do this. A RDDL document 
describes a namespace, not a document. What you propose might be 
useful in and of itself, but it would replace RDDL.

>While there are many namespaces that, right or wrong, can stand alone in
>documents, and thus have associated schemas, there are schemas that define
>document with a namespace mix. Those schema don't have a particularly
>associated namespace, so they can't appear in a RDDL document.

That's true in some schema languages, including DTDs. However, it is 
decidedly not true in the W3C XML Schema Language. Regardless, 
there's no reason I can't include a mixed schema as a resource within 
a RDDL document for just one namespace. I can even include a schema 
for a totally different namespace as a related resource within a RDDL 
document. RDDL is very flexible.

>- As an illustration of the previous issue, it is rather funny to think that
>RDDL itself is out of its own scope. Granted, the RDDL documentation is an
>RDDL document. But like I wrote before, you cannot use the RDDL resolution
>mechanism to go to http://www.rddl.org/RDDL from a RDDL document.

Not sure why you would want to go there, but you most certainly can 
use it to go to http://www.rddl.org/, which is the RDDL namespace URL

>Show me the algorithm. I have asked for it twice, but nobody answered. I'm
>not asking for heuristics (like "I have a look at the namespace
>declarations, see those XHTML, RDDL and XLink namespace names, and decide to
>go for the RDDL one") or science-fiction ("I fetch all RDDL documents from
>each and every namespace name I find, and merge them together"). I want an
>algorithm that can be easily implemented today, if the fate of RDDL is to be
>used today.

An algorithm to do what exactly? The algorithm to find the RDDL 
document associated with any given namespace URI is trivial, the 
algorithm to find all RDDL documents associated with any namespace 
URIs in the document only slightly less so. Of course, there is no 
algorithm to find the RDDL document associated with a given XML 
instance document because there is no such RDDL document.

>And once you've shown me the algorithm, show me the same algorithm for
>XHTML+SVG, WAP 2.0, and my proprietary schema that mix namespaces. Hint :
>the algorithm has to be exactly the same.

Trivial, in each case load all the namespace URLs. (You'll probably 
get some exceptions because not all of these will resolve to RDDL 

>-- describing document meta-data may not be the intended purpose of RDDL,
>its author may purposely have restricted their scope to describing
>namespaces meta-data. But in that case, this has to be written clearly
>somewhere in the RDDL documentation, and a lot of use cases for RDDL should
>be marked as non implementable. There are people casting silver bullets from
>RDDL, which is the main reason why this thread is so big.

The authors never intended RDDL to manage nuclear power plants or 
describe airplane controls, either. Should they explicitly deny 
RDDL's use for those purposes? Do they have to deny everything you 
can't do with RDDL? RDDL's about describing namespace names. I never 
heard anybody except you and Paul T. claim it was for anything else.

| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
|          The XML Bible, 2nd Edition (Hungry Minds, 2001)           |
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