xml-dev - Re: namespaces and document structure [Re: Next Round]

[Tyler Baker <tyler@infinet.com>]

james anderson wrote:

> Tyler Baker wrote:
> >
> > james anderson wrote:
> >
> > > yes, but...
> > ...
> > > Neither the prefix nor the qualified name have the same permanence as the
> > > local name, the namespace and the expanded name. One could well collect all
> > > prefixes in connection with which as symbol appeared, but the values are of no
> > > use as the bindings have dynamic extent.
> > > the prefix and the qualified name need to be handled separately, through an
> > > interface which combines symbols (here called names) with a dynamic parsing or
> > > serialization  context.
> > >
> > > The other additions have to be modified accordingly: as the prefix has no
> > > meaning outside of the parser's dynamic context, those interfaces have no purpose.
> >
> > Very true, but sometimes applications (or even the DOM) may want to preserve the exact
> > document structure in memory and be able to write out that exact document structure as
> > well.  That is the only reason for providing the prefix and qualified name methods.
> >
>
> The prefixes bear no relation to document structure. **Strictly speaking**
> neither they nor even the URI's have anything to do with content. They simply
> aid in identifying the names which figure in the content. That the prefixes
> appear in bindings which appear as attributes is a (regrettable) anomoly, but
> it does not change their nature.
>
> (When I hear of application which process *prefixes* I'll take this back.)

You may have content which is processed by multiple applications, some of which are
namespace aware and some which are not.  Some applications may want to do their own
namespace processing and will want to know the exact document structure of the original
document.  Hey, when I hear of an application which actually uses "Namespaces in XML" I'll
take a lot of things back.  It would be nice if some developers here could post examples of
successful uses of "Namespaces in XML" so we have some sort of context to move forward with
intregating "Namespaces in XML" into SAX.

> As "mr. Bray's" algorithm makes clear, a given document actually is an
> instance of an infinately large equivalence class in which the same "content"
> appears in varying encodings, each of which employs difference prefixes to
> bind respectively identical namespaces. The particular prefixes in one
> encoding have no bearing on the ability to write out the same document
> structure. To the extent that they affect the ability to duplicate the
> *encoding* they do so as a consequence of the relation between prefixes and
> *namespaces*, not as a consequence of the relation between prefixes and
> individual *names*.

Plain and simple, each Name belongs to a particular namespace at a given point in time.  The
prefix meanings may be volatile, but for applications which want to know "exactly" what the
text of the original document looked like (for example editors), I think exposing namespace
prefixes, or at a minimum the qualified name would be a good thing.

Tyler


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