Output Port report for validation steps

Hi list,

the editors draft specification of "XProc 3.0: Validation Steps" 
describes the p:validate-with-relax-ng, p:validate-with-schematron, and 
p:validate-with-xml-schema step for XProc 3.0.

I'd like to suggest the output port "report", which is part of the 
p:validate-with-schematron step, for the two other validation steps 
relax-ng and xml-schema as well.

I am quite aware that the existence of SVRL, the Schematron Validation 
Report Language, seems to be a fundamental difference between Schematron 
and to the two other types of validation. There is no standardized way 
to report validation errors from XSD or Relax NG validation. However, 
SVRL is only a recommended option. It is not a requirement that a 
full-conformance implementation shall be able to generate validation 
reports in SVRL. So that there is no standardized way to report 
validation errors from Schematron validation as well. This is reflected 
in the "Validation Steps" spec by the statement "Schematron assertions 
and reports, if any,mustappear on the|report|port. The outputshouldbe 
in/Schematron Validation Report Language/(SVRL)."

Why not define a output port "report" for xml schema and relax ng like 
"/validation reports, if any, must appear on the report port/"? I think 
it would be helpfull.

Our team is dealing with the electronic invoices, defined by the 
european norm EN 16931. To check whether any xml document conforms to 
this standard, we have some steps of validation, First is validation 
with xml against UBL 2.1 schema, second is validation with schematron 
against business rules defined in EN 16931. We tried to define and 
implement this in xproc and failed. Thats because, if a document would 
pass all validation steps, we are fine. But if not, the receiver wants 
to know what exactly went wrong. He needs a detailed error report for 
his records. This is true also in case of xml schema validaton errors, 
and that can't be done with either the current xproc spec since there is 
no way to report xml schema validation errors.

Of course, xml schema validation errors would be reported in a 
proprietary format. Thats bad, but it is definitly better than nothing. 
Our validator software applies XSLT to the saxon-specific report format 
to generate something that is similar to SVRL. Same could be done for 
other XML validation processors.


Sincerely,

Frank Steimke