Just require URLs

Carl Hage carl at chage.com
Mon May 31 19:02:42 BST 1999


From:           	"Jonathan Borden" <jborden at mediaone.net>

> Paul Hunter wrote:
> > Using HTTP for URIs sounds intrinsically <em>bad</em> to me.  ...
...
> No one has offered a hard or
> practical example of an actual problem this creates, aside from offending
> of the sensibilities.

Turn it around-- it would be intrinsically <em>good</em> to require
all namespaces to reference a retrievable document. Any existing 
namespace registry can be mapped into a backwards compatible 
HTTP URL, returning something, e.g. http://isbn.org/isbn/1-57595-
180-0B could return the USMARC data (card catalog) formatted in 
HTML with a link to an XML representation. It serves as a URI as 
well as a source of documentation.

Software that maps hytime namespaces can just as easily map 
http://hytime.org/ namespaces, and software that knows nothing of 
hytime namespaces could follow a URL to find needed info. (Maybe 
manually, but better than nothing.)

I think the URI identifying namespaces and DTDs should be URLs 
not URNs. An XML document without retrievable documentation on 
the DTD should be considered non-compliant. The biggest problem 
isn't syntax-- it's the semantics. XML validators based on DTDs will 
only identify an insignificant percentage of errors-- hardly worth it if 
you ask me unless debugging software. (Though considering how 
Microsoft and Netscape callously violate HTML standards, I may 
need to recant.)

Likewise, a DTD->HTML converter doesn't produce human readable 
documentation, because the most important part (semantics) is 
missing.

If you ask me, XML will really work only when XML-Schema (or 
whatever) is enhanced to include human-readable detailed 
documentation (with all code-values defined in an XML thesaurus),
and the URIs in XML/DTD headers lead to a retreivable version of 
this. Putting the semantics and code-value definitions in separate 
paper documents (the norm today) must be abandoned. Instead 
everything needed should be accessable at the other end of the 
namespace URL.



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Carl Hage                                              C. Hage Associates
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<http://www.chage.com/chage/>                          Sunnyvale, CA 94086

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