Trippi-Sail Triplestore Adapter

Introduction

This module allows Sesame Sail-compliant triplestores to be plugged into the Trippi triplestore interface, ultimately allowing them to be used with the Fedora Commons Repository.

Requirements

This module requires the following:

• Tomcat >= 7.0
• A Sesame Sail compliant Triplestore

Compilation

The code should be able to be built with Maven 3, simply cloning the repository, navigating into the cloned repository and calling:

mvn package

By default, this builds against Fedora 3.8.1. To build against other versions of Fedora, the fedora.version parameter can be passed, something like:

mvn package -Dfedora.version=3.7.1

Packaging should generate both a zip and tar.gz file inside of the target directory.

NOTE: To run the "remote" Blazegraph tests, the remoteBlazegraph property must be passed:

# Assuming Blazegraph is running on port 9999 on the localhost.
mvn package -DremoteBlazegraph=http://localhost:9999/blazegraph

Installation

1. Install your Sail-compliant triplestore. NOTE: Do not put it in the same servlet container as Fedora, since Fedora cannot be running when rebuilding the RI.

2. Extract the archive onto your target machine. Let's assume we have extracted it into /opt/trippi-sail.

3. Configure Fedora to know of the extracted JARs, in $CATALINA_BASE/conf/Catalina/localhost/fedora.xml:

   <Context>
   	<Loader
   		className="org.apache.catalina.loader.VirtualWebappLoader"
   		virtualClasspath="/opt/trippi-sail/*.jar"
   		searchVirtualFirst="true"/>
   	[...]
   </Context>

   NOTE: It may be desirable (or necessary) to add other paths to the virtualClasspath value if you are using a triplestore, in order to make the relevant classes available for the next step.

4. Use Spring Bean configuration to inject a org.openrdf.repository.Repository implementation into our org.trippi.impl.sesame.SesameSession class. See the examples in the src/main/resources/sample-bean-config-xml directory from the source or /opt/trippi-sail/example-bean-xml directory from the extracted binary package for examples. The XML file should be created in $FEDORA_HOME/server/config/spring.

5. Remove the reference to the resource index datastore in $FEDORA_HOME/server/config/fedora.fcfg; commenting it out should suffice. The section in particular is something like:

   <server xmlns="http://www.fedora.info/definitions/1/0/config/" class="org.fcrepo.server.BasicServer">
       [...]
       <module role="org.fcrepo.server.resourceIndex.ResourceIndex" class="org.fcrepo.server.resourceIndex.ResourceIndexModule">
           [...]
           <!-- Remove/comment out following param[@name="datastore"] bit in this module. -->
           <param name="datastore" value="localMulgaraTriplestore">
               <comment>(required)
                   Name of the triplestore to use. WARNING: changing the
                   triplestore running the Resource Index Rebuilder.</comment>
           </param>
           [...]
       </module>
       [...]
   </server>

6. The RI rebuild does not use the same classloader used by Tomcat, so the above virtualClasspath is not sufficient. In order to be able to run the rebuild, the classpath will have to be added to the rebuild command. The easiest way to do this is to prepend to the -cp entry in $FEDORA_HOME/server/bin/env-server.sh; enter the path to the directory, followed by an asterisk, like: /opt/trippi-sail/*.

7. Trippi as embedded in Fedora itself can have Sesame/OpenRDF jars built-in, which cause NullPointerExceptions when querying, so it may be necessary to move/rename $CATALINA_BASE/webapps/fedora/WEB-INF/lib/openrdf-sesame-onejar-{version}.jar such that it is not eligible for the classloader (change the extension away from jar or delete the file entirely, or move it somewhere else)..

8. Now, we should be clear to stop Fedora, rebuild the RI and start Fedora, and that should be it: You should now be running Fedora with your other triplestore backing the RI.

Troubleshooting/Issues

Having problems or solved a problem? Contact discoverygarden.

Maintainers/Sponsors

Current maintainers:

• discoverygarden

Development

If you would like to contribute to this module, please check out our helpful Documentation for Developers info, Developers section on Islandora.ca and contact discoverygarden.