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- From: David Megginson <email@example.com>
- To: "XML Developers' List" <firstname.lastname@example.org>
- Date: Sat, 20 Mar 1999 10:16:35 -0500 (EST)
James Robertson writes:
> Having done a transformation with 12 steps in the chain,
> I would disagree that the DTD becomes a big problem.
> If you're using a tool like Omnimark,
... or Perl, etc. ...
> you can choose to view the document as SGML or text. In general, a
> lot of the steps use the latter, with some simple find-and-replace
That's a kludge that works when you have end-to-end lexical control of
the SGML, but not otherwise. You have to know for certain (for
example) that you won't have to deal with pathological cases like
<!-- <em> --></em>
Fine-grained lexical control is rare in major enterprise projects,
where people might be using five different tools and several different
software systems to produce the SGML that feeds into the front end.
> So in practice, we just ended up with about 5 DTDs that were very
> close to each other.
> Not a lot of work.
It depends, again, on the complexity of the project. If there are,
say, a project manager, three UI specialists, a sysadmin, a DBA, ten
software engineers working on the DB and transformations, five DTD
consultants (with a DTD co-ordinator), and two publishing specialists
working in the chain, the difficulties of co-ordinating even small
changes become near exponential, especially if the team is scattered
across the continent (as is common in large enterprises).
It can be done (I know from my own experience), but it's quite
different from a situation where you and a couple of associates
control all of the parts of the chain yourselves, and the original
SGML's requirement for a DTD makes the problem that much harder.
> And it did ensure that all was correct at each stage, catching
> errors in a most satisfying way.
Yes, that can be a great advantage, but like anything, it requires a
cost/benefit analysis. If I ask a customer "Do you want DTD
validation at every stage", she'll say yes; if I ask her "Are you
willing to risk ending up paying an extra US$200,000 to have DTD
validation at every stage", she might hesitate (remember, everyone's
time costs money, not just the DTD designer's).
Maybe she'll still say yes, depending on her requirements and budget,
but at least with XML (and WebSGML) the choice isn't forced on her.
All the best,
David Megginson email@example.com
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