Access to DUL.owl ontology

Hello.

Currently, I'm working on an ontology definition aligned to Semantic Sensor
Network Ontology (SSN) <http://purl.oclc.org/NET/ssnx/ssn>, which, in turn,
is aligned to the Dolce Ultra-Lite upper ontology
<https://www.w3.org/2005/Incubator/ssn/wiki/SSN_Skeleton#Aligning_the_SSN_Ontology_and_the_core_SSO_design_pattern_with_DOLCE>
.

One can see <https://www.w3.org/2005/Incubator/ssn/ssnx/ssn#Module_DUL>
that in the SSN ontology spec, the DUL IRI namespace is:
*http://www.loa-cnr.it/ontologies/DUL.owl
<http://www.loa-cnr.it/ontologies/DUL.owl>*

However, it seems that this "link is broken", due that the IRI doesn't
point the the proper DUL.owl definition.

I'm trying to see/generate a data model visualization of SSN via the
tool WebVOWL
(Web-based Visualization of Ontologies)
<http://vowl.visualdataweb.org/webvowl.html>.

For this, I'm following this IRI:
http://vowl.visualdataweb.org/webvowl/#iri=http://purl.oclc.org/NET/ssnx/ssn

However, it fails due that it cannot find/retrieve DUL's definition:
{
*Could not load imported ontology:
&lt;http://www.loa-cnr.it/ontologies/DUL.owl&gt
<http://www.loa-cnr.it/ontologies/DUL.owl&gt>; Cause: Problem parsing
http://www.loa-cnr.it/ontologies/DUL.owl
<http://www.loa-cnr.it/ontologies/DUL.owl>*
*Could not parse ontology.*
}

Questions:

   - Is there any standard way to handle this "broken link" when aligning
   to upper ontologies?
   - Should DUL.owl be fixed?
   - Should SSN address this situation "somehow"?
   - If I'm aligning to SSN, how I should address this situation?

Thank you for your feedback.

/$¡rm
Best regards,

Sergio José Rodríguez Méndez (羅士豪)
Pervasive Embedded Technologies Laboratory (PET Lab)
Computer Science Department
National Chiao Tung University