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Re: why do namespaces have such a bad rep (was Re: Experimenting with Na

  • From: "Steven R. Newcomb" <srn@t...>
  • To: xml-dev@i...
  • Date: Wed, 1 Apr 1998 11:25:01 -0500

namespaces bad

James Anderson <James.Anderson@m...> writes:

> why do namespaces have such a bad reputation? in particular, why are
> they discredited for having been conflated with something which they
> are not, and which they do not claim to be?

I'm not making this up.  These are the kinds of ideas that some very
smart people brought home from the XML Conference in Seattle last
week.  I was called from the conference and told, with breathless
excitement, that XML does inheritance via an XML facility called
"namespaces".  I don't know how it happened, and I'm not blaming
anyone, but it's pretty clear to me that RDF was oversold there, as
were namespaces.  And it's easy to see how this misunderstanding would
mushroom: when you use an element type name from another document
type, and say so, and if you don't know the history of RDF, or the
real significance of context in document architectures, or the stated
limitations on the purpose of namespaces, wouldn't it follow (as a
"least hypothesis", if nothing else) that you intend this element to
be treated as if it were that other element type?  (This is a mistake
that I, for one, could easily make!)

> why? what does colon syntax have to do with class inheritance?

Expectations created by vague recollections of OO syntaxes that use
colons to delimit class names.  No more, no less.  I'm not claiming
that it's a logical or appropriate presumption.  I'm just observing a
fact.  Real people -- people I respect -- are misunderstanding what's
happening here, and in a big way.  Moreover, it's a difficult
misunderstanding to clear up, and clearing it up inevitably casts
Fear, Uncertainty, and Doubt on the whole XML thing, which is
something I really don't want to do.

> the namespace 'thing' maps the names from the "inherited from (sic)
> DTD" into a unique region of a two dimensional namespace. it says
> nothing at the structure.

Yes.  I said that.

> > RDF was looking for was a way to guarantee global uniqueness of
> > element type names, and if we ever try to get anything more than that
> > from namespaces, we are on very thin ice indeed.

> agreed, but it doesn't claim to.

That's right.  However, the fact is, people need inheritance.  The
closest thing XML provides today is namespaces.  The unsophisticated
are confusing namespaces with inheritance.  This is a Bad Thing for
XML and W3C, because when their eyes are opened, these people will
feel betrayed and their honeymoon with XML will suddenly be over.
"You mean there's no XML way for me to say that I want to treat this
element as if it were this other element type in this other document
type?  What kind of pseudo-object-oriented horseshit is this XML
thing, anyway?"  And when you consider that namespaces are a
suboptimal approach to the problem RDF is designed to address -- the
very problem that was presumably the excuse for railroading namespaces
through the committee process without the due consideration that has
been the hallmark of excellence in the rest of the XML process
(including the RDF process, except for this namespace business) -- I'm
afraid namespaces look very bad indeed.

> the wd doesn't propose to collapse the architecture, it proposes to
> map the names.

Yes.  I said that.

> > Anyway, all is not lost.  This namespace thing is a mistake that will
> > necessarily be corrected, simply in order to support the needs of
> > civilization in an XML-dominated world.  The way toward a solution is
> > already paved by an ISO standard (ISO/IEC 10744:1997 Annex A.3) that
> > is being adjusted to accommodate the syntactic limitations of XML
> > (i.e., its lack of #NOTATION attributes).  It is implemented in the SP
> > parser and in other software systems, and it is already being used in
> > many industrial contexts.  It's the right sort of answer, it's not
> > going away, and its usage is accelerating rapidly; there was a
> > manyfold increase in the number of papers reporting its use at
> > SGML/XML 97.

> it also has equivalent mechanisms to manage the same problem within a
> one-dimensional namespace.
> (i.e. the problem doesn't go away)

Huh?  What problem doesn't go away?

> some may find the ability to rename an advantage, as it allows one
> to alter the intended semantics. i wonder whether it as often leads
> to confusion. where the issue is really name-uniqueness, namespaces
> are a much more compact expression.  there's no reason they couldn't
> be integrated into sgml architectures - but for the deconstructivist
> aims, they'd accomplish the same thing as the renaming attribute...

Do you think that providing a mechanism for renaming things is all
that inheritable architectures have to offer?  If so, you'd better
study this topic some more.  That's just a housekeeping feature.

> why wouldn't people just take them for what they are - orthogonal to
> the issue of structure, and use them for what they can do?

Because:

* people need inheritance more urgently than they need namespaces;

* if they had inheritance they wouldn't need namespaces (even your
  "greater compactness" argument will not stand up to scrutiny because
  the ISO inherited architectures syntax can make much more compact
  documents than the proposed namespace syntax ever could);

* nothing else in XML, today, even looks like inheritance; and 

* there is nothing in XML, today, that does inheritance.

However, if the W3C would simply acknowledge that an XML-ready
mechanism and syntax for true architectural inheritance is already
available in an existing ISO standard, this whole problem would
vanish, and the XML honeymoon would not end with disappointment.  Why
don't they just do that?  Or, alternatively, just use the ideas,
change all the names, and maybe add some web-application-specific
stuff, as was done with HyTime hyperlinking in X-Link?

-Steve

--
Steven R. Newcomb, President, TechnoTeacher, Inc.
srn@t...  http://www.techno.com  ftp.techno.com

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