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> From: Jonathan Robie [mailto:firstname.lastname@example.org]
> I don't have good statistics on this, but I sure do see a lot
> more schemas
> in the real world than you seem to. Most of the applications
> I see that
> need datatypes together with XML are using XML Schema for
> this. Most of
> these applications use simple schemas, basically the "DTD+Datatypes"
> subset, though there are also quite a few uses of groups and
> some other
I'm seeing the same in our market (for our integration interfaces). We are
largely adhering to simple schemas, though they do go a bit beyond what DTDs
could accomodate. Also, we have adapted our integration interfaces to be a
bit more "schema-friendly". XML Schema does have some restrictions in what
it can model, and we are having to accomodate those restrictions.
A year ago, none of our customers really showed any interest in XML Schema.
Today, we are getting requests from customers for XML Schemas for message
formats for integrations. We are also starting to see interest in Web
Service standards (e.g. SOAP). I would add that our product suite is sold to
sales and marketing organizations. These don't tend to be very bleeding edge
in their use of technology (although this varies among companies).
> Database applications are an important class of
> where datatypes matter, and it's no accident that database
> vendors are
> strongly behind XML Schema.
Also, for application integration. Even when a database is not involved,
datatypes are important. I'm personally a big fan of RELAX NG (+ simple
datatypes), but XML Schema is the language blessed by the W3C, so it gets
all of the intention. None of our customers are asking for RELAX NG schemas;
they are asking for XSD schemas.
I hope the interoperability issues can be resolved, but I also hope that the
W3C works constructively with the ISO DSDL effort, and that from that effort
we will see greater awareness in the market of alternatives and can more
practically avail ourselves of alternatives in those circumstances where the
complexity of XML Schema is really not needed. Right now, that's not
practical because the market is not paying much attention to anything
happening outside of the W3C, and in spite of rhetoric to the contrary on
this list, one can find nothing in any W3C documents that acknowledges there
are alternative schema languages that deserve recognition. (Correct me if
I'm wrong on this latter point, but I've been unable to find anything to
> Does anybody have real data on the market penetration of XML
> Schema? I
> think that vendor support for XML Schema is clear, but if
> Adam is right,
> that's irrelevant. Vendors seem to believe that people are
> actually using
> XML Schema, too. Are they right? Do we have real evidence on
> this question?
I have no hard statistics, but given that we are finding that our customer
base is showing interest in XML Schema, and our customer base represents a
somewhat conservative (with respect to technology) segment of the market, I
would say that the speculative claim of about 1% of users using XML Schema
is extremly dubious -- and even those not currently using XML Schema often
have plans to start using it. If I were to extrapolate from our customer
base, I would put the estimate at closer to the 10-20% range and growing.