The Web uses Uniform Resource Identifiers (URIs) as a global identification system. A URI is used to identify a resource, such as a document or an abstract thing, either by a location, such as a DNS host name and a path on that machine, or a name.

When identifying real-world objects using a URI, you can choose Hash URI or 303 URI. The differences are as follows:

  • Hash URI: for smaller and stable sets of resources that evolve together, e.g. RDF Schema vocabularies and OWL ontologies. The advantage is that all resources are in the same file, because the redirection target cannot be configured separately for each resource.
  • 303 URI: for large-scale data sets that are likely to grow over time. One document can be used for describing either each or all resources. When using 303 URI for an ontology, it can reduce a client’s performance and cause higher latency.


Importing and Exporting URI/IRI

  • The Concept Modeler imports and preserves the URI or IRI for every OWL class and property from an OWL ontology file as the tagged value on the corresponding UML class and property in the Concept Modeler.
  • When exporting this particular model back to OWL, the Concept Modeler will not apply the normal automatic URI/IRI generation.

  • It will preserve the URI or IRI from the original OWL ontology, so that the classes and properties can be used with their correct URIs/IRIs.

  • The export URI style option also has no effect on the preserved URI or IRI.