Hi Jens.
On 05/01/09 20:01, Jens Deppe wrote:
> Hi Jack,
>
> You might also consider putting the schema into a processing
> instruction statement. That way you could still have it easily
> extracted by other XML tooling such as XPath.
Thanks for your suggestion. If you mean add the version to the schema
and then read the schema as an ordinary XML file, I tried that but ran
into a problem. I tried adding a version to the schema header first,
and then to the schema itself. I could extract that information just
fine when I read the schema as an ordinary XML file, but the validator
(xmllint) complained when I used the schema to validate the manifest.
Thanks,
Jack
>
> --Jens
>
> Jack Schwartz wrote:
>> Hi Ethan.
>>
>> I think I figured out a way to do RelaxNG schema versioning.
>>
>> Where we had left it when we talked earlier, the document you pointed
>> me to (www.xfront.com/Versioning.pdf) had good ideas, but without a
>> schema versioning mechanism, they were hard to implement.
>>
>> RelaxNG schemas don't allow versioning in their headers, but we can
>> put the schema version in a comment in a RelaxNG schema to workaround
>> this. We can then have the parser validate the manifest against it
>> before using the manifest.
>>
>> The thing missing by putting the version in the comment instead of
>> the header (as in a DTD) is that there is no mechanism for the parser
>> proper to check it. No problem though... ManifestServ can add a
>> check of its own to look for the special comment in the schema (a
>> grep through the file, perhaps) to extract the version number. Next,
>> it would pre-parse the manifest to get the version of the manifest
>> and do the compare. If the check passes, preprocessing ensues and
>> the data is prepared for consumption by AI.
>>
>> As long as the schema version is in the schema somewhere, and the
>> parser knows how to find and check it, its robustness is the same.
>> It doesn't matter whether it is in a comment or in a header.
>>
>> Do you see any holes or omissions here, or does this make sense?
>> Other thoughts?
>>
>> Thanks,
>> Jack
>>
>>
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