Re: Use of XML for config files

[Darren New <dnew@san.rr.com>]

Stephen Leake wrote:
> 
> Darren New <dnew@san.rr.com> writes:
> 
> > Stephen Leake wrote:
> > > I am an XML beginner. I gather the <key name="foo">value</key> style is
> > > more amenable to definition via DTD or schema? What other virtues does
> > > it have?
> >
> > On the other hand, it says less. So you cannot, for example, say "the foo
> > package must configure a bar and a baz." You could do that if the format was
> > <foo>
> >   <bar>My stuff</bar>
> >   <baz>Your stuff</baz>
> > </foo>
> 
> Do you mean "in the DTD, you cannot say .."? Are you implying that
> each app should have its own DTD? I guess that makes sense.

I'm saying that if each app has its own DTD, that DTD can say that a foo
includes a bar and a baz. If the style of <key name="something">value</key>
is used, then the DTD for all config files will be the same. 

In the former case, you get extra checking, extra specification, and more
readable config files, at the expense of having different DTDs for each
config file.

In the latter case, you have the advantage of having a fixed number of keys
to look at, but the application has more work to do to check the
correctness.

In the former case, you could also have things like
<recent_files>
  <file> My Work.doc </file>
  <file> Nancy.jpg </file>
  <file> http://www.adapower.com </file>
</recent_files>

Altho you could probably do that with the <key> syntax, it wouldn't be
nearly as clear, I expect.

INI files, of course, use recent.1, recent.2, recent.3 and so on.

> In this case, I'm guessing that we could have one DTD for all config
> files. But you are right, it would not say much, so maybe that is not
> useful.

Right. It's basically the same as a INI file, semantically speaking. That
is, all the checking that everything needed is there the right number of
times is left up to the application, rather than the config file definition.

-- 
Darren New 
San Diego, CA, USA (PST). Cryptokeys on demand.
** http://home.san.rr.com/dnew/DNResume.html **
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