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   Re: Architectural Forms and XAF

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  • From: Arjun Ray <aray@q2.net>
  • To: xml-dev <xml-dev@xml.org>
  • Date: Sat, 26 Feb 2000 08:01:42 -0500 (EST)

On Fri, 25 Feb 2000, Tim Bray wrote:

> I'm pretty sure that what AFs do is a superset of what namespaces
> do.  David Megginson has proved conclusively that using namespaces
> doesn't get in the way of using AFs.

IOW, namespaces are unnecessary and insufficient. :)

Consider this reworked, but rather familiar example:

  <?xml:arch public-id="http://www.w3.org/HTML/1998/html4" 
             form-att="h" auto="yes" ?>
  <?xml:arch public-id="http://www.xml.com/books" 
             form-att="xdc" auto="no" ?>
      <title>Book Review</title>
    <body xdc="bookreview">
      <div xdc="title">XML: A Primer</div>
        <tr align="center">
          <th>Author</th> <th>Price</th>
          <th>Pages</th> <th>Date</th>
        <tr align="left">
          <td xdc="author">Simon St.Laurent</td>
          <td xdc="price">31.98</td>
          <td xdc="pages">352</td>
          <td xdc="date">1998/01</td>

> The only reason why the AF framework wasn't used to do the job of
> namespaces (and yes, we thought about it a lot) is that the syntax
> for AF-ing attributes is ugly and complicated.

"Ugly" and "complicated" are both value judgments - enough that a
dissenting opinion is worth recording.  

  -  I'll grant that a number of people find practically *all*
     of SGML/XML syntax imperishably ugly.  But, if syntax like
        ... name="value" ...
     is ugly, then it's by no means clear how colonifying names
     suddenly beautifies matters.
  -  Considering how some attribute values can have very complex
     internal syntax (URLs come to mind), I wonder what's so
     complicated about a series of tokens
        ... renamer="old1 new1 old2 new2..." ...
     none of which are individually more complicated than a name.

> The syntax for namespaces is uniform for attributes and elements,
> and much simpler.  

I find namespace usage in practice hideously verbose and cluttered.  
Actually, I've yet to see a *good* example non-trivially contrasting
"ugly and complicated" with "uniform and simpler".  So far, onlookers
get plugs for one side and... potshots at the other.

> Not simpler because of better design, just simpler because it's
> trying to solve a much smaller problem.

We all know that the whole business *started* with colonified names.
Apparently, the syntactic device by itself created enough warm fuzzy
feelings in some quarters that, come what may, *some* problem for this
solution just had to be, um, found.

"The bottomline is that it is really difficult to solve a problem when
the problem does not exist." - Masataka Ohta.

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