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At 7:30 PM -0800 1/17/02, Paul T wrote:
>PS. It appears that people, who write articles about RDDL,
>are already providing the general public with misleading
>information about RDDL (exactly, like it was with
>XML Namespaces. As we should remember, each
>and every XML book or article was explicitly saying that
>Namespaces URLs "point to nothing" and that's the
>idea of them. Which is no longer true.)
>
Really? You've really read "each and every" one? Looking at my own
books I see in XML in a Nutshell, 1st edition:
Namespace URIs do not necessarily point to any actual document or
page. In fact, they don't have to use the http scheme. They might
even use some other protocol like mailto in which URIs don't even
point to documents. However, if you're defining your own namespace
using an http URI, it would not be a bad idea to place some
documentation for the specification at the namespace URI. The W3C got
tired of receiving broken link reports for the namespace URIs in
their specifications so they added some simple pages at their
namespace URIs. You are by no means required to do this, though. Many
namespace URIs lead to 404-Not Found errors when you actually plug
them into a web browser. Namespace URIs are purely formal
identifiers. They are not the addresses of a page, and they are not
meant to be followed as links.
The XML Bible is a little less clear that you can place something at
the end of a namespace URI, but still doesn't come close to saying
that you can't and that that's the whole idea of them. From the 1st
edition:
The URI that defines a namespace is purely formal. Its only purpose
is to group and disambiguate element and attribute names in the
document. It does not necessarily point to anything. In particular,
there is no guarantee that the document at the URI describes the
syntax used in the document; or, for that matter, that any document
exists at the URI. Having said that, if there is a canonical URI for
a particular XML application, then that URI is a good choice for the
namespace definition.
These were all written pre-RDDL but seem pretty accurate to me.
--
+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
+-----------------------+------------------------+-------------------+
| The XML Bible, 2nd Edition (Hungry Minds, 2001) |
| http://www.ibiblio.org/xml/books/bible2/ |
| http://www.amazon.com/exec/obidos/ISBN=0764547607/cafeaulaitA/ |
+----------------------------------+---------------------------------+
| Read Cafe au Lait for Java News: http://www.cafeaulait.org/ |
| Read Cafe con Leche for XML News: http://www.ibiblio.org/xml/ |
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