[regrep-comment] Add validation mechanism to ebXML reg/rep

[John Silva <johns@anr.ms.philips.com>]

In the HL7 usage of ebXML reg/rep there is a need to
validate submitted conformance profiles against a
defined XML Schema. It would be useful if the ebXML
spec defined an extensible (pluggable) validation
mechanism much like content based discovery, to
validate objects submitted to ebXML reg/rep by
ObjectType. There could be a hierarchy of validations
available, for example, for XML documents there could
be the default XML well-formedness check, optionally
followed by a DTD validation, followed by an XML Schema
validation, followed by a Schematron validation, etc.
However, this could be a little difference from CBD in
that there could be a chaining of validations not just
a single validation per ObjectType.

In our particular use case in HL7 conformance profiles,
we are going to specify XML Schema as well as Schematron
rules to help pin down the [syntactic]  requirements of our submitted
profiles. Sun has tools that will do XML Schema and Schematron
validation that can be 'pipe-lined' together to do the kind of
validation we need.

Also, there is an additional validation requirement on metadata
submitted along with content.   For example, if we have a particular
type of object setup in our registry (HL7ConformanceProfile) we
would like a mechanism in ebXML reg/rep that ensures that ALL
submittals to the reg/rep enforce a particular set of metadata along
with the content.    This is needed to ensure consistency of metadata
in the registry so that when users search for content of a particular
objectType, that they can be sure that all content of that type has
consistent metadata (indices).

   Thanks,
       John Silva
       Email:  johns@anr.ms.philips.com
      Contributor on ebxmlrr.sourgeforge.net