XML and standards (was Re: Integrity in the Hands of the Client)

Paul Prescod papresco at technologist.com
Mon Nov 24 09:01:06 GMT 1997

Mark Baker wrote:
> At 12:01 PM 23/11/97 -0500, Paul Prescod wrote:
> >Putting angle brackets around troff does
> >not make troff into a serialization of a Java Bean
> What if that troff document contained a link to an implementation of a
> troff formatter?  What if that implementation described its interface using
> XML?

What if it didn't? What if it described its interface using CORBA or
some proprietary language that is more powerful than CORBA? You don't
lose any flexibity or expressive power, you just have to write another
parser for CORBA or your proprietary language. 

The hard part of writing a troff implementation is not writing the
parser, but in writing the formatter. So XML can only make a marginal
difference in implementation time or effort. The hard part of writing an
interface to a troff implementation is writing the interface, not
publishing it (in my experience, anyway) so XML can only make a marginal
difference there either. The same goes for writing an SGML DTD parser.
The difficulty there is in keeping track of all of those elements,
attributes and entities, not in parsing the syntax. So again you only
get a marginal benefit from using XML as the representation language.

Now if a marginal benefit is enough to tip you into profitability, then
I'm glad we were able to help you. But there are costs associated with
that marginal benefit. You will beat your head against the wall trying
to express constraints that SGML cannot express directly. You will find
that your files are much larger than they would be in an optimized
notation. You will notice redundancy in places that you don't really
need it.

On the other hand, there is a huge benefit to using SGML/XML *for
documents* because SGML is the international standard for representing
structured documents. Thus you get the benefit of hundreds of tools,
books and experts, almost all of them specialized for document markup.
You do not get that benefit when you ignore CORBA (the real object
interface standard) to use XML instead. You do not get that benefit when
you ignore TeX or troff to use XML as a page description language. You
do not get that benefit when you ignore the existing DTD syntax to
invent a new XML instance syntax.

When you use XML to replace an existing standard, you are, for a period
at least, actually working against open standards and promoting a
proprietary alternative, even if it is expressed in the standard
notation of SGML/XML. This might be a good idea if there is a problem
with the existing standard in a given area, but more often it is a
better idea to work with the people who control the standard to improve
it rather than striking out on your own (for all of the usual reasons).

 Paul Prescod

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