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The package org.dspace.rdf.providing contains the servlet to provide the converted data as serialized RDF. In the last days I added a second servlet, which is not part of the image yet. The LocalURIRedirectionService is used if you use the LocalURIGenerator. Linked Data distinguish between non-information and information-resources. If a URI of a non-information resource is dereferenced it should forward to the URL of an information resource describing the non-information resource. With Handles or DOIs the resolver will perform the forward. For local URIs the LocalURIRedirectionService will do. The package org.dspace.rdf.providing.negotiation contains the classes for content negotiation. Linked Data uses content negotiation to serve the same information as html or different serializations of RDF under the same URI.
Installation
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The installation follows the normal installation of a DSpace source release. In addition you have to provide a Triple Store. You can use any Triple Store you like, if it support SPARQL 1.1 Query Language and SPARQL 1.1 Graph Store HTTP Protocol. If you do not have one yet, you can use Apache Fuseki. Download Fuseki from its official download page and unpack the downloaded archive. The archive contains several scripts to start fuseki. Use the start script appropriated for the OS of your choice with the options '--localhost --config=<dspace-install>/config/modules/rdf/fuseki-assembler.ttl'. Instead of changing into the directory you unpacked fuseki to, you may set the variable FUSEKI_HOME. If you're using Linux, unpacked fuseki to /usr/local/jena-fuseki-1.0.1 and istalled DSpace to /var/dspace this would look like this:
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| Warning |
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The configuration DSpace contains configures Fuseki to provide a SPARQL endpoint that can be used to change the data of the Triple Store. You should not use this configuration and let Fuseki connect to the internet as it would make it possible for anyone to delete, change or add information to the Triple Store. The option --localhost tells fuseki to listen only on the loopback device. You can use Apache mod_proxy to make the read-only SPARQL endpoint accessible from the internet. A more detailed documentation on how this can be done will follow here one day. |
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Configuration
The file [dspace-install]/config/modules/rdf.cfg is the main configuration file of dspace-rdf. It contains information on how to connect to the triple store, which class should be used as URIGenerator, which plugins will convert the repository content to RDF, which URL is used in the content negotiation to reach the DataProviderServlet and so on. It contains a lot of comments, so please take a look into the configuration file until there is a better documentation of dspace-rdf.
In the folder [dspace-install]/config/modules/rdf/ you'll find more configuration files. The files named
RDFizer
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[dspace-install]/bin/dspace dsrun org.dspace.rdf.RDFizer --help |
Development / API
TODOs
dspace-rdf is realized as a new module of DSpace as it contains a webapp and everyone should be able to decide whether it should be deployed or not. The webapp is used to provide the data in serializations of RDF (RDF/XML, Turtle, N-Triples and N3-Notation).
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