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Gustaf Liljegren <firstname.lastname@example.org> wrote:
| Ever since XML Schema started to evolve and the talk about datatypes in
| XML took off, I've been wondering secretly why XML validation needs the
| concept of datatypes at all.
| XML is a plain text format, so content validation in XML should be no
| different from regular pattern matching.
And referential consistency checking (as in IDREF/ENTITY/NOTATION declared
values.) Exactly right.
| If my application wants an integer, all I'd do would be to check if all
| characters are in the range 0-9. Regular expressions would be enough for
| that. If possible, I'd have this check written in the schema, or some
| special module of patterns attached to the schema.
Again, exactly right. Semantics are at the application level, and the
universe of semantics is unbounded. Try to shoehorn this into XML - a
lexical formalism - invites the Farglebarp Problem [*], in spades. The
politics of it so far have determined that a bunch of DB-wonks and type
theorists have been allowed to transfer the costs of "standardizing" their
particular hobbyhorses onto everyone else.
(IOW, the fundamental problem with XML Schema is not technical: it's
social. But geeks have a habit of shying away from such unmentionables.)