Re: [PyWrapper-devel] Valid response model

[Roger H. <ro...@td...>]

Thanks for the kind words Markus. I'm glad some one is glad I am =20
trying to do this ;) I hope it doesn't end up with too much work for =20
you.

I have narrowed down this problem to a simple test case.

This is a more simple XSD with a single import and it works fine:

http://localhost:8080/pywrapper/pywrapper?op=3Dschema&location=3Dhttp://=20=

rs.tdwg.org/ontology/voc/xsd/test1.xsd

The second version is just the same but includes the use of an =20
attribute reference in the imported file:

http://localhost:8080/pywrapper/pywrapper?op=3Dschema&location=3Dhttp://=20=

rs.tdwg.org/ontology/voc/xsd/test1_broken.xsd

and it doesn't work!

Looking at the logs

The error message is

"PyWrapperError: Global element reference 'http://rs.tdwg.org/=20
ontology/voc/Test2#/rdf:about' missing"

But we have a slightly earlier log message saying

2006-12-15 16:14:14,789 - DEBUG from pywrapper.model: =20
self._globalRefs=3D[u'http://www.w3.org/1999/02/22-rdf-syntax-ns#/=20
@about', u'http://rs.tdwg.org/ontology/voc/Test2#/MyElement', =20
u'http://www.w3.org/1999/02/22-rdf-syntax-ns#/RDF', u'http://=20
www.w3.org/1999/02/22-rdf-syntax-ns#/MyRdfString']

So it looks to me like it is just getting the namespace of the =20
attribute reference wrong and so not finding it in the globalRefs =20
look up. It does it right for the element but not for the attribute.

Looking at the code for _buildAttribute(self, attrs) on line 269 in =20
structure_handler.py  it  doesn't mention namespace (unlike the =20
_buildElement attribute) and it confuses me as it seems to pass the =20
type as the namespace to the Attribute object it creates.

Now this code all looks like clever stuff and I don't want to go =20
trying to fix anything when I don't really know what I am doing - =20
though I will have a go if no one else wants to. You may be able to =20
fix this in minutes rather than my hours and would probably create =20
fewer bugs .

It may be that I am doing something bad in the XSD although I am =20
pretty confident I am OK on that.

Would once again be grateful for you comments,

Roger




On 14 Dec 2006, at 10:48, Markus D=F6ring wrote:

> Hi Roger,
> that's exactly what we were all thinking of doing for some time =20
> already. Good finally someone DOES it!
> The xml schema parser inside pywrapper is a custom implementation. =20
> I couldnt find any existing schema parser out there, honestly. So =20
> as you can imagine this is a pretty tough job and I have tried it =20
> with many different schemas and progressed in implementing xml =20
> schema, but still dont support all of it (for example references =20
> and patterns).
>
> Well, and your RDF schema is honestly the most complex I've seen =20
> that was fed to pywrapper.
> So I tried to trace the problem and as you see pywrapper complaints =20=

> that the attribute  http://rs.tdwg.org/ontology/voc/TaxonName#/=20
> rdf:about  is being referenced, but is nowhere defined.
> pywrapper expands all namespace prefixes into the full namespace. =20
> So in this case http://rs.tdwg.org/ontology/voc/TaxonName# is the =20
> targetnamespace of the imported lib/TaxonName.xsd schema file. So =20
> in there I suspect is a reference to rdf:about, which pywrapper =20
> thinks is an attribute name. I think this is because I cant find =20
> anywhere the prefix rdf: being defined properly. I suspect oXygen =20
> and alike know what rdf: means. So try to add a namespace =20
> declaration to the schemas (for owl etc too). Then pywrapper should =20=

> expand rdf:about into the full qualified name http://www.w3.org/=20
> 1999/02/22-rdf-syntax-ns#about and hopefully find the global =20
> declaration of rdf:about in the lib/rdf.xsd schema.
>
> But again, I think I've never tried a schema with that many =20
> namespaces and imports so I keep my fingers crossed...
>
> Please let me know what happens!
> Markus
>
>
>
> On Dec 13, 2006, at 11:29 PM, Roger Hyam wrote:
>
>> Hi All,
>>
>> I am looking at what TAPIR output models I could use with =20
>> PyWrapper. I have developed XML Schemas that will help produce =20
>> valid RDF instance data for a simple OWL ontology. Here is an =20
>> example:
>>
>> http://rs.tdwg.org/ontology/voc/xsd/TaxonName/schema.xsd
>>
>> If you open this link in OxygenXML or Spy you can expand all the =20
>> nodes and create instance documents that look like valid RDF. Here =20=

>> is an example instance document:
>>
>> http://rs.tdwg.org/ontology/voc/xsd/TaxonName/template.xml
>>
>> So the plan would be to use the schema above (or something =20
>> similar) as the structure in an output model so that a TAPIR =20
>> response could be a valid semantic web document and a LSID =20
>> metadata response. A complete LSID authority would need very =20
>> little code on top of this.
>>
>> The downside is that these schemas are complex because of the =20
>> number of imports required to support the different namespaces =20
>> involved.
>>
>> Anyhow. The first step was to check that PyWrapper would parse =20
>> schemas like the one above so I did this:
>>
>> http://localhost:8080/pywrapper/pywrapper?=20
>> op=3Dschema&location=3Dhttp://rs.tdwg.org/ontology/voc/xsd/TaxonName/=20=

>> schema.xsd
>>
>> on my local machine and got
>>
>> "The models response structure is invalid: Global element =20
>> reference 'http://rs.tdwg.org/ontology/voc/TaxonName#/rdf:about' =20
>> missing"
>>
>> I am not sure why I get this as OxygenXML doesn't have a problem =20
>> with expanding the links and validating the rdf:about attribute so =20=

>> I *think* the schema is OK. The parser is handling the import of =20
>> TaxonName.xsd OK. Is it a problem with attributes? Is it a bug or =20
>> a known limitation or an error in my schema?
>>
>> The are also problems with the group element but I can always work =20=

>> round this by just repeating the element.
>>
>> Any ideas on the rdf:about problem would be most welcome.
>>
>> Many thanks,
>>
>> Roger
>>
>>
>>
>>
>>
>> ****************************************
>>   Roger Hyam <ro...@td...>
>>   Biodiversity Information Standards
>> ****************************************
>>
>>
>> ---------------------------------------------------------------------=20=

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