Identifying XML Document Types (was XML media types revisited)

Paul Prescod paul at
Thu Jan 21 00:11:07 GMT 1999

> Namespaces Disadvantages: 

Surprisingly (to me) I find these arguments to be unpersuasive. Namespaces
seem like the right solution to me.

> Just because the root element is X doesn't mean its contents
> are Y. 

If the definition of the namespace (whereever it is) says that the
namespace's X must contain a Y, then an X *must* contain a Y, just as if
it were a DOCTYPE declaration. The only difference is that the validation
is done at some other level, using some other mechanism.

> Especially given the problems of validating documents in
> namespace-aware environments, namespaces may not always be available.  

These problems go away if you use the namespace convention in ways that
are not in contradiction with validation (i.e. #FIXED xmlns: attributes).

> Half
> the XML community regards Namespaces as the worst thing since the plague.

I suppose, but if we agreed that they solved the problem you describe then
maybe less people would hate them.

> Because namespaces aren't supposed to point to anything, you can't sneak a
> DTD in at the URL identified by the namespace.

That's what the DOCTYPE or architectural use declaration is for. Your real
complaint is that there is no way to automatically invoke a schema
processor based on a namespace declaration alone. My response is that
there is also no way to automatically invoke a stylesheet engine or
speech-to-text reader. The complaint about pointers to DTDs is only more
relevant if you posit that every namespace should always be associated
with a single schema and that schema should be a DTD. That can't be the
case if we are going to allow non-DTD schemas.

 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself

Don't you know that the smart bombs are so clever, they only kill 
bad people."

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