ERROR value of "severity" attribute in XML output conflicts with WARNING message

[bitsgalore]

Looking at the XML output of Epubcheck 4.0.2, sometimes the value of the "severity" attribute in a message element contradicts the actual warning/error message. To illustrate this see below EPUB:

epub20_crazy_columns.epub

I run this through Epubcheck using:

java -jar epubcheck.jar epub20_crazy_columns.epub -out epub20_crazy_columns.xml

The output contains a validation message about about the use of absolute positions:

<message severity="error" subMessage="CSS-017">CSS-017, WARN, [CSS selector specifies absolute position.], OEBPS/Styles/styles.css (13-1)</message>

It is strange that the severity attribute states that this is an error, whereas the text message says it is a warning. Seeing that this file passed validation I'm assuming that internally Epubcheck considers this to be a warning.

Another example is this file:

epub20_encryption_binary_content.epub

Here Epubcheck reports:

<message severity="error" subMessage="HTM-023">HTM-023, WARN, [An invalid XHTML Named Entity was found: '&amp;0;'.], OEBPS/Text/pdfMigration.html (18-197)</message>

Which again shows the same problem.

[tofi86]

This clearly looks like a bug. Thanks for reporting it, we'll take a closer look!

@tledoux you introduced this in PR #673 for issue #486 - can you probably have a look at this? Thanks!

[tledoux]

Indeed, the main issue is that the schema jhove.xsd allows only two values for the severity attribute

<xs:attribute name="severity" use="optional">
  <xs:simpleType
    <xs:restriction base="xs:string">
      <xs:enumeration value="error"/>
      <xs:enumeration value="info"/>
    </xs:restriction>
  </xs:simpleType>
</xs:attribute>

So I had to decide how to map from the levels of epubcheck to these two values.
Currently the mapping is:

EpubCheck level	severity attribute
fatal error	error
error	error
warn	error
hint	info

Maybe I should have made another choice? Should I lower the warn to info?

[bitsgalore]

Hmm, tricky one. I'm not in favour of mapping the Epubcheck Warning level to jhove's "error" level, b/c epubcheck being a validator most users will expect this to be something that causes the validation to fail (which it doesn't).

Another option would be to add a "warning" level to the JHOVE schema and see if that gets accepted by the JHOVE maintainers (OPF). That change wouldn't cause any existing (valid) JHOVE output files to fail validating against its schema, and I think this could be useful for JHOVE as well. Not sure if they'd be open to this but perhaps worth a try?

[tofi86]

Ah, well, I remember the discussion about that, @tledoux.

Personally I'm not very happy with the JHOVE schema anyway and would suggest to implement a EpubCheck prorietary schema once in a while. But for now we should stick to the JHOVE and do our best.

Should we remove the severity attribute entirely? Would be my best guess...

[tofi86]

Any comments on that topic? Shall we remove the severity attribute or leave it as it currently is?

[tofi86]

Any suggestions?

I'm voting for removing the severity attribute. Shall we do that with EpubCheck 4.1?

[rdeltour]

I'd be in favor of keeping it as-is for 4.1, and maybe document this particularity (which can be confusing I agree).

In a next version however, we should revamp the XML format entirely, and we could possibly use a custom XML flavor (based on EARL?) on which we would have better control. People can always contribute XSLTs to convert to their flavor of choice.

[tofi86]

Thanks @tledoux for pushing a fix in PR #814 and using severity info in the XML format for warning messages from EpubCheck.

I'm okay whith that for the moment, but will open another issue to not forget to implement another XML structure in a future release.

[tofi86]

See issue #816 for further discussing a new XML output schema.

[rdeltour]

Since this is a breaking change, and most publishing workflow reject EPUBs with warnings, and we didn't receive that much feedback about this, I will leave this issue open and remove it from the v4.1 milestone.

Thank you @tledoux in any case for the PR, let's keep it open as well until we decide how to further proceed!

[tledoux]

As described in the PR, the new jhove schema allows for a 'warning' level which allows to map directly epubcheck levels with severity.
It also has an 'id' attribute to handle the id of an error.

I hope this PR could really fix this issue.