Weighing in on XSL / Standards

Joshua E. Smith jesmith at kaon.com
Sun May 23 16:35:15 BST 1999

Well, I read the articles on XML.com, and I've read all the arguments here.
 I'm still pretty much an outsider on all this, and I've *never* programmed
in any language who's name ends in "SL" so take this for what it's worth:

- Declarative programming languages, and by this I mean rule-based,
production-based, then-if, backward chaining, expert-system, like that,
take a *LOT* of getting used to.  That does not mean they are *bad*.  One
you have the epiphanal ah-ha moment, they can be a remarkably expressive
and easy thing to use.  I have seen some amazing work done in very few
lines of code in the AI field (I'm thinking, specifically, of the Soar
system out of CMU, UofM [Laird], and ISI [Rosenbloom]).

- To those of us who have thought forward-chaining, procedurally since our
epoch as programmers, it is hard to see production systems as anything but
black magic.  I used to have this bias myself, until a really smart guy
showed me how forward and backward chaining systems can actually be
transformed into one another, and therefore, it's really just a matter of

- A big part of the reason why you don't find tools like debuggers,
packages, modules, etc., in production systems is because you don't need
them.  Production systems naturally solve big problems with small amounts
of code.  The lack of such tools is thus a specious argument.  It's like
saying it's hard to adjust the fuel/air mixture with a screw driver on an
engine with no carburator.  Yes, I suppose it is.  And why would you need
to do that, exactly?

- It is often argued by the expert systems guys that production-based rule
systems (or "case based reasoning") is *more* intuitive than
forward-chaining, procedural, algol-derivative programming.  The theory is
that ordinary experts can write rules, but only programmers can write
algorithms.  I have no idea if this is true, I've never seen any evidence
that it is, but it is an article of faith in that community, and might help
to explain why the XSL camp seems to have a lot of "religion" about ease of

- The argument that a new standard is not needed because existing standards
can do the same job is specious.  Is TCP unnecessary because you could have
written your own windowing and framing code on plain old IP?  (Yeah, I know
I'm doing historical revision here, and TCP actually came before IP, but
pretend you don't know that, so you can see my point.)  [I'm basically
making the same argument someone else did earlier about SQL vs assembly

- The W3C seems a little schizophrenic in their treatment of what is worthy
of standardization.  There is the IETF model: take a collection of working
solutions, resolve the differences, and standardize the results.  There is
the US Dept of Defense model: invent a brand new thing, declare it a
standard, mandate it's use, then implement it.  XML is an example of the
IETF model: they took a good, working, thing (SGML) and tidied it up.
ECMA-Script is another good example of the IETF model.  From my viewpoint,
XSL looks like an example of the USDoD approach.  Am I missing some history
here?  When a detractor can say, with a straight face, that he doubts the
standard can actually be implemented, that's usually a sign that the
standard is *way* out in front of the community, and needs more baking.

I lived in the USDoD standards world for a long, long time, and I know that
their process is completely incapable of producing anything with any value
whatsoever.  I have also dabbled in the IETF standards world, and have been
uniformly impressed at how their process lets the cream rise to the top.
Since the W3C is all about the Internet, why does it have a process
separate from that of the IETF?  I dont' get that.  Can someone explain
that to me?  Does it have to do with paper documents or something?

So my take on the argument, in a nutshell: Somebody needs to go implement
XSL, develop some great apps using it, in the process fix everything which
is wrong with it, and then offer it up as a standard.  Standards bodies
should be editors, not authors.

-Joshua Smith

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