RDF2TM Mappings

This plug-in helps you configure the RDF to Topic Maps mappings in your Omnigator. Specify the desired mapping for each property using the selection box and press Confirm to accept proposed and/or changed mappings.

Each RDF property can be mapped to a characteristic (a basename, occurrence, or association) or to an identifier (subject identifier, subject locator, or source locator); or else it can be ignored.

A table of existing mappings (usually mapping.rdff in the Omnigator's topicmaps directory) is used to record mappings for later use.

When the Omnigator encounters a property for which no mapping exists it makes a "best guess" proposal based on the kinds of values exhibited by the property: Properties whose values are literals are mapped to occurrences; those whose values are URIrefs or blank nodes are mapped to associations. These proposed mappings can sometimes be improved as follows:

• Some properties whose values are literals (e.g. dc:title) are more appropriately mapped to basenames (or scoped basenames).

• Some properties whose values are URIs (e.g. foaf:homepage) are more appropriately mapped to (external) occurrences.

• Other properties whose values are URIs (e.g. skos:subjectIndicator) might be more appropriately mapped to an identifier.

Properties are used to type the resulting occurrences and associations, or to scope basenames. Thus, for example, dc:description properties mapped to occurrences will result in occurrences of type dc:description; foaf:knows properties mapped to associations will result in associations of type foaf:knows; and foaf:nick properties mapped to scoped basenames will result in basenames scoped by foaf:nick.

The role types of associations are set to the predefined subjects rdf2tm:subject and rdf2tm:object (where rdf2tm is the namespace <http://psi.ontopia.net/rdf2tm/>).

The technical details of this mapping are described in an Ontopia Technical Report.