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This optional feature allows an administrator to provide a list of custom namespace prefixes that will override the default prefix registry. The custom namespaces are loaded on start-up via a YAML file. The namespaces can be modified while Fedora is running. Changes may take a few minutes to take effect.
Below is a sample YAML namespace configuration file, custom_namespaces.yml. Notice the "awesome" prefix definition at the bottom of the list. We will use this in the following example. NB: the custom file will override all default namespace prefixes. In other words, the custom file becomes the definitive registry. Any namespaces that are not prefixed will be returned as full URIs in the response.
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premis: http://www.loc.gov/premis/rdf/v1#
test: info:fedora/test/
memento: http://mementoweb.org/ns#
rdfs: http://www.w3.org/2000/01/rdf-schema#
webac: http://fedora.info/definitions/v4/webac#
acl: http://www.w3.org/ns/auth/acl#
vcard: http://www.w3.org/2006/vcard/ns#
xsi: http://www.w3.org/2001/XMLSchema-instance
xmlns: http://www.w3.org/2000/xmlns/
rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
fedora: http://fedora.info/definitions/v4/repository#
xml: http://www.w3.org/XML/1998/namespace
ebucore: http://www.ebu.ch/metadata/ontologies/ebucore/ebucore#
ldp: http://www.w3.org/ns/ldp#
dcterms: http://purl.org/dc/terms/
iana: http://www.iana.org/assignments/relation/
xs: http://www.w3.org/2001/XMLSchema
fedoraconfig: http://fedora.info/definitions/v4/config#
foaf: http://xmlns.com/foaf/0.1/
dc: http://purl.org/dc/elements/1.1/
awesome: http://example.com/awesome/ |
Fedora can activate the file by using the -Dfcrepo.namespace.registry system parameter, either on the command line or by adding it to the list of other params that provide paths to other configuration files:
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mvn jetty:run -Dfcrepo.namespace.registry=/my/fedora/path/custom_namespaces.yml |
In order to demonstrate how this feature works, try starting Fedora without defining a custom namespace registry:
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mvn jetty:run |
Once Fedora is running, run the following curl command
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echo "@prefix awesome: <http://example.com/awesome/> . <> awesome:stuff 'waffle' ." | curl -u fedoraAdmin:fedoraAdmin http://localhost:8080/rest/test -X PUT -H "Content-Type: text/turtle" --data-binary "@-" |
When you retrieve this resource,
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curl -i -u fedoraAdmin:fedoraAdmin http://localhost:8080/rest/test |
notice the new predicate is expressed as the full URI.
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@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix fedora: <http://fedora.info/definitions/v4/repository#> .
@prefix ldp: <http://www.w3.org/ns/ldp#> .
<http://localhost:8080/rest/test>
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<http://example.com/awesome/test> "waffle" ;
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Also notice there are built in prefixes for common namespaces. Now restart Fedora with the custom namespaces yml enabled:
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mvn jetty:run -Dfcrepo.namespace.registry=/my/fedora/path/custom_namespaces.yml |
Retrieve the item and see how your custom namespace prefix is being used.
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curl -ufedoraAdmin:fedoraAdmin http://localhost:8080/rest/test
@prefix awesome: <http://example.com/awesome/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix fedora: <http://fedora.info/definitions/v4/repository#> .
@prefix ldp: <http://www.w3.org/ns/ldp#> .
<http://localhost:8080/rest/test>
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awesome:test "waffle" ;
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More information on this feature can be found at the Best Practices - RDF Namespaces page.