Re: [xsl] How do you ensure that data is not altered/corrupted in a transformation?

["Paul Tyson phtyson@xxxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Years ago when I had this challenge, I used Schematron.

You write a stylesheet to generate schematron rules from your source 
xml. The schematron rules say what you expect to see in the transformed 
file, based on the structure and content of the input file. These rules 
can be be as simple or complex as you want, depending on the validation 
requirements.

After transforming the source, you run the schematron-generated xslt 
against the output file.

If your validation needs are simple, you could skip the schematron part 
and just generate a stylesheet to check for all required elements, 
attributes, and content in the output file.

As others have mentioned, all this could be choreographed using xproc.

Regards,
--Paul

On 5/19/23 05:13, Michael Kay mike@xxxxxxxxxxxx wrote:
> Testing, testing, testing. Plus tools to help prevent the mistakes arising in the first place.
>
> Schema validation can catch a lot of the errors, but it won't catch them all.
>
> We had a case like this where a customer was flagging up dangerous levels of some reading in medical reports by displaying the relevant figures in red. When they upgraded from XSLT 1.0 to 2.0, the test $level > $dangerLevel started doing a string comparison rather than a numeric comparison, with the effect that the red flags weren't appearing -- and it took them months to notice, because they weren't doing enough testing. Hopefully no-one died. Tests are the only answer: and because stylesheets can be thrown together quickly, people often neglect to follow good software engineering disciplines when changing them.
>
> Michael Kay
> Saxonica
>
> > On 19 May 2023, at 09:37, Roger L Costello costello@xxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hi Folks,
> >
> > In certain domains loss of life may occur if data is altered/corrupted in any way.
> >
> > Suppose you write an XSLT program which transforms this:
> >
> > <alt>12000 feet</alt>
> >
> > to this:
> >
> > <altitude>12000 feet</altitude>
> >
> > How do you ensure that the data -- 12000 feet -- was not altered/corrupted in the transformation?
> >
> > I have heard of people doing a hash on the data prior to the transformation, a hash on the data after the transformation, and then comparing the hashes. Is that what you would do when lives are on the line? What is your recommendation?
> >
> > /Roger