Another myth to debunk...

Stefan writes:

But I don't think WSDL is a good candidate for making this point, since with its reliance on XML Schema it's probably the least flexible and most static part of the whole Web services architecture.

Since when does WSDL rely upon WSDL?

The WSDL2.0 draft has the following pseudo schema for the types component:

<definitions>

  <types>

    <documentation />?

    [extension elements]*

  </types>

</definitions>

Aside from the WS-I Basic Profile 1.0 which does constrain the use of XML Schema for WSDL1.1 descriptions (although as with WSDL2.0 any schema definition language can be used), there is no reason why the definition of the WSDL types couldn't be RelaxNG or schematron or anything else for that matter.

And I really don't understand why XML Schema would be considered inflexible or static. David Orchard has been blogging on the topic of versioning XML Schema and Web services. It isn't XML Schema holding things back in this regard. Rather, it is the hard-wired data binding (blech!) that so many are enamored of that makes things unnecessarily complicated in this regard.