...
dspace-rdf is an extension for DSpace that adds capabilities to convert contents stored in DSpace into RDF, to store the converted data in a Triple Store and to provide it as serializations of RDF. The Triple Store must support SPARQL 1.1 and can be used to provide the converted data over a read-only SPARQL endpoint. dspace-rdf can currently be found on my github repositoriy, but I would be glad to contribute it to a future version of DSpace.
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. dspace-rdf contains several parts. You can see a simplified class diagramm here:
...
The package org.dspace.rdf.conversion contains the classes used to convert the repository's content to RDF. The conversion itself is done by plugins. The Interface org.dspace.rdf.conversion.ConverterPlugin is really simple, so take a look if you want to extend the conversion. The only thing important is, that the plugins must only create RDF that can be made publicly available (see Design Decisions for further information). The MetadataConverterPlugins is heavily configurable (see below) and is used to convert metadata of Items. The StaticDSOConverterPlugin can be used to add static RDF Triple (see below). The DSORelationsConverterPlugin is not configurable yet. It is just a proof of concept and its revision is on the TODO list below.
...
| Warning |
|---|
The configuration of Fuseki DSpace provides configures it to provide a SPARQL endpoint several SPARQL endpoints, even some 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. |
...
And of course a good English documentation is necessary as this document only gives a little peak on how to configure and use dspace-rdf.
Design Decisions
I decided to add a Triple Store to the repository so that no data needs to be converted at the moment the converted data is accessed. This decision was done with the idea in mind that contents of repositories will much more often be read as changed. To avoid big changes in the core of DSpace and to make it easy to use dspace-rdf in existing repositories I decided that the Triple Store should extend the repository and not replace the relational database. The Triple Store can be considered as a cache for the converted data. Beside that it should be used to provide a read-only worldwide accessible SPARQL endpoint containing all converted data. The Triple Store should contain only data that is public as the access restriction of DSpace won't affect the SPARQL endpoint. For this reason dspace-rdf converts only archived, discoverable (non-privat) Items, Collections and Communities that are readable for anonymous users. Plugins converting Item metadata should check whether as specific metadata field needs to be protected or not ().