> From: Bullard, Claude L (Len) [mailto:]
> XML is good for HAS-A; not too good for IS-A.
Why not? Because a child node defaults in "has-a" in human eyes? The
only difference is that it seems natural. Both "has-a" and "is-a" need a
syntax scheme + interpretation algorithm. "is-a" presents a more
complicated description even for humans. Essentially it is just an
enhanced "has-a" + property, where the property comes with it's own
"has-a" and "is-a" :-)
> XML is good for data objects; not so good (in fact, rotten)
> for object-oriented objects.
A certain design may have rotten parts but one cannot argue against the
usefulness of it. I see OO influenced XML structures gaining ground
every day from RDFS to SOAP to JSML[1] and for good reasons. They
provide for cool stuff from MVP to plain multilanguage serialization and
they escape the useless hype of implementations that suffer from the
"relational normalization rules" you mention below (i.e. my favorite
vendor's database module that outputs or "supports" XML)
> XML is pretty good for tables, but not so good
> for enforcing relational normalization rules.
Of course. Enforcing relational normalization rules shuts down most good
reasons to use XML in the first place, with the possible exception of
exchanging DB data between servers via http.
> XML is primarily syntax. The rest are applications
> of languages that use that syntax or orthogonal
> systems designed to process data objects that use
> that syntax.
>
> Many of the mistakes I encounter come of trying
> to make of XML what it is not. XML can express
> many styles of data laden trees, but that is
> where it stops. The two ways guaranteed to
> get howls are to design an XML type that exactly
> mimics the implementation, then claim that is a
> generalized solution (usually, a claim that
> it should be a standard) or to create a
> generalized solution (usually a standard) and
> hand that to an implementer who knows it
> doesn't apply to his or her problem (the
> case for LegalXML is weak outside the US,
> and I suspect this is true of many e-gov
> and e-business specifications for XML
> document types and schemas).
>
> XML Doesn't Care. That's why it scales.
> XML implementors have to care; that is why
> they freak out a lot.
Agreed.
[1] www.jsml.org
Cheers,
Manos
