Trippi RDF SPI implementation using SPARQL Update over HTTP.

To build (requires Java 8):

cd trippi-sparql ; mvn clean install

This will result in a large trippi-sparql-*.jar JAR in the trippi-sparql/trippi-sparql/target/ directory which contains the connector and its dependencies, and a trippi-sparql-fcrepo-webapp-*.war WAR in trippi-sparql/trippi-sparql-fcrepo-webapp/target . To use this connector with Fedora 3, this large JAR can be dropped into the WEB-INF/lib/ directory of a Fedora 3 web-application, or the WAR file can be used (it is simply the ordinary Fedora 3 web-application with the JAR pre-installed). Then, a <datastore/> element must be configured in fedora.fcfg. An example is shown below featuring the various parameters available. For each parameter except connectorClassName and updateEndpoint, a default will be used if no <param/> element for that parameter is supplied. The default value for each parameter will be the value shown in the example below, except that the default for the SPARQL CONSTRUCT Query endpoint is just the ordinary SPARQL Query endpoint, and the default for the ordinary SPARQL Query endpoint is the SPARQL Update endpoint. The default for graphName is as shown, but users should be aware that any relative URI used there (the default #ri is as used by Fedora 3's Mulgara configuration) will be resolved against a base URI configured in the parameter uriBase with default as shown below. Queries transmitted through Fedora's Resource Index API will be automatically equipped with an appropriate BASE declaration, but otherwise, clients that use the SPARQL endpoints directly are responsible for ensuring that the base URI is used correctly. A convenience method SparqlConnector::rebase is available for the purpose.

<datastore id="sparqlTriplestore">
    <comment>Triplestore addressed by SPARQL-over-HTTP used by the Resource Index</comment>
    <param name="connectorClassName" value="edu.si.trippi.impl.sparql.SparqlConnector">
        <comment>The name of the Trippi Connector class used to communicate with the triplestore.</comment>
    </param>
    <param name="readOnly" value="false">
        <comment>Whether this connector is going to be read-only in operation.</comment>
    </param>
    <param name="graphName" value="#ri">
        <comment>The URI of the named graph in which triples will be managed.</comment>
    </param>
    <param name="uriBase" value="info:edu.si.fedora">
        <comment>The base that will be used to resolve a graph name that is a relative URI.</comment>
    </param>
    <param name="maxHttpConnections" value="10">
        <comment>The maximum number of clients in the HTTP client pool used for SPARQL Update requests.</comment>
    </param>
    <param name="initialTripleStorePoolSize" value="3">
        <comment>The initial number of sessions in the triplestore pool.</comment>
    </param>
    <param name="maxTripleStorePoolGrowth" value="-1">
        <comment>The maximum number of additional sessions to add to the triplestore pool. If specified as -1, no limit will be placed on pool growth.</comment>
    </param>
    <param name="spareTripleStorePool" value="1">
        <comment>The number of spare sessions to maintain in the triplestore pool.</comment>
    </param>
    <param name="updateEndpoint" value="http://localhost:3030/fuseki/update">
        <comment>The URL of a SPARQL Update endpoint for the triplestore to be used with this connector.</comment>
    </param>
    <param name="queryEndpoint" value="http://localhost:3030/fuseki/query">
        <comment>The URL of a SPARQL Query endpoint for the triplestore to be used with this connector. This endpoint will be used for non-CONSTRUCT queries.</comment>
    </param>
    <param name="constructEndpoint" value="http://localhost:3030/fuseki/query">
        <comment>The URL of a SPARQL Query endpoint for the triplestore to be used with this connector. This endpoint will be used for CONSTRUCT queries.</comment>
    </param>
    <param name="autoFlushDormantSeconds" value="5">
      <comment>Seconds of buffer inactivity that will trigger an auto-flush. If this threshold is reached, flushing will occur in the background, during which time the buffer is still available for writing.</comment>
    </param>
    <param name="bufferSafeCapacity" value="40000">
        <comment>The maximum size the buffer can reach before being forcibly flushed. If this threshold is reached, flushing will occur in the foreground and the buffer will be locked for writing until it is finished. This should be larger than autoFlushBufferSize.</comment>
    </param>
    <param name="bufferFlushBatchSize" value="20000">
        <comment>The number of updates to send to the triplestore at a time. This should be the same size as, or smaller than autoFlushBufferSize.</comment>
    </param>
    <param name="autoFlushBufferSize" value="20000">
        <comment>The size at which the buffer should be auto-flushed. If this threshold is reached, flushing will occur in the background, during which time the buffer is still available for writing.</comment>
    </param>
</datastore>

Lastly, the <module role="org.fcrepo.server.resourceIndex.ResourceIndex"/> section must be altered so that the value of the value attribute in<param name="datastore"/> is the ID used above for the new <datastore/>, e.g.

<module role="org.fcrepo.server.resourceIndex.ResourceIndex" class="org.fcrepo.server.resourceIndex.ResourceIndexModule">
    <comment>Supports the ResourceIndex.</comment>
    <param name="datastore" value="sparqlTriplestore">
        <comment>(required)  Name of the triplestore to use. WARNING: changing the  triplestore running the Resource Index Rebuilder.</comment>
    </param>
    …
</module>