• From: "Stephen Green" <stephengreenubl@g...>
• To: "Greg Hunt" <greg@f...>
• Date: Thu, 27 Dec 2007 09:33:21 +0000

But you accept that making things mandatory in the schema will
have the side-effect of making it permanent too (if you have a
forwards-compatibility versioning strategy and commitment)? And
this leads to the strong motivation to change semantics instead,
which is a dangerous kind of change.

So by avoiding application validation in addition to the schema (does
anyone actually ever not validate in the application after the schema
validation - don't most turn schema validation off after test phase and
use application level validation instead??) you have created an even
greater need for even more complex (perhaps impossible) validation
in the application - validation of the semantics :-)

On 27/12/2007, Greg Hunt <greg@f...> wrote:
> And if we engage in "avoidance of making things mandatory" for any reason
> other than enforcing real business data constraints we reduce the value of
> schema-driven validation.  Doing that requires the applications to do their
> own structural validation to enforce the business requirements for
> mandatory-ness which in turn makes implementing changes or assessing the
> impact of a change even harder.
>
> Greg

• Follow-Ups:
  • Re: Caution using XML Schema backward- or forward-compatibility as a versioning strategy for data exchange
    • From: "Greg Hunt" <greg@f...>

• References:
  • Caution using XML Schema backward- or forward-compatibility as a versioning strategy for data exchange
    • From: "Costello, Roger L." <costello@m...>
  • Re: Caution using XML Schema backward- or forward-compatibility as a versioning strategy for data exchange
    • From: "Stephen Green" <stephengreenubl@g...>
  • Re: Caution using XML Schema backward- or forward-compatibility as a versioning strategy for data exchange
    • From: "Greg Hunt" <greg@f...>