Apache Jena
Jump to navigation
Jump to search
What is Apache Jena?
- https://jena.apache.org/
- https://en.wikipedia.org/wiki/Apache_Jena
- https://en.wikipedia.org/wiki/Draft:Apache_Fuseki (Draft in progress/review as of 2020-06-28)
- https://www.wikidata.org/wiki/Q1686799
First Steps
The goals are:
- Setting up an Apache Jena instance
- loading some data
- starting a Fuseki server
For Querying your data your might want to look at the SPARQL tutorial in this wiki.
When i first tried to get Apache Jena and the Fuseki server running i had some issues doing so. This page is to share how i solved the issues e.g.
Also some things are done slightly different here then the "standard" Apache Jena way. This is to avoid having to learn the details of Jena configuration but go with standard Unix and shell script approaches instead. We try to use things as much "out of the box" as possible.
Script to download Apache jena and load initial data with tdb2.tdbloader
#!/bin/bash
# WF 2020-05-10
# global settings
jena=apache-jena-3.16.0
tgz=$jena.tar.gz
jenaurl=http://mirror.easyname.ch/apache/jena/binaries/$tgz
base=/hd/luxio/gnd
data=$base/data
tdbloader=$jena/bin/tdb2.tdbloader
getjena() {
# download
if [ ! -f $tgz ]
then
echo "downloading $tgz from $jenaurl"
wget $jenaurl
else
echo "$tgz already downloaded"
fi
# unpack
if [ ! -d $jena ]
then
echo "unpacking $jena from $tgz"
tar xvzf $tgz
else
echo "$jena already unpacked"
fi
# create data directory
if [ ! -d $data ]
then
echo "creating $data directory"
mkdir -p $data
else
echo "$data directory already created"
fi
}
#
# show the given timestamp
#
timestamp() {
local msg="$1"
local ts=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
echo "$msg at $ts"
}
#
# load data for the given data dir and input
#
loaddata() {
local data="$1"
local input="$2"
timestamp "start loading $input to $data"
$tdbloader --loader=parallel --loc "$data" "$input" > tdb2-$phase-out.log 2> tdb2-$phase-err.log
timestamp "finished loading $input to $data"
}
getjena
export TMPDIR=$base/tmp
if [ ! -d $TMPDIR ]
then
echo "creating temporary directory $TMPDIR"
mkdir $TMPDIR
else
echo "using temporary directory $TMPDIR"
fi
if [ ! -f authorities-kongress_lds.ttl ]
then
wget https://data.dnb.de/opendata/authorities-kongress_lds.ttl.gz
gunzip authorities-kongress_lds.ttl.gz
fi
loaddata $data authorities-kongress_lds.ttl
Script to start Fuseki server
This script tries to avoid the complexity described in https://jena.apache.org/documentation/fuseki2/fuseki-configuration.html by using the --loc parameter
Don't run this script with version 3.16.0 - use 4.3.1 at least to avoid log4shell vulnerability!
#!/bin/bash
# WF 2020-06-25
# Jena Fuseki server installation
# see https://jena.apache.org/documentation/fuseki2/fuseki-run.html
version=3.16.0
fuseki=apache-jena-fuseki-$version
if [ ! -d $fuseki ]
then
if [ ! -f $fuseki.tar.gz ]
then
wget http://archive.apache.org/dist/jena/binaries/$fuseki.tar.gz
else
echo $fuseki.tar.gz already downloaded
fi
echo "unpacking $fuseki.tar.gz"
tar xvfz $fuseki.tar.gz
else
echo $fuseki already downloaded and unpacked
fi
cd $fuseki
java -jar fuseki-server.jar --tdb2 --loc=../data /gnd
SSH tunnel to make port 3030 available
The default installation of Fuseki only allows connections from localhost. If you don't want to bother with the configuration you can use a SSH tunnel like this:
ssh -L 3030:localhost:3030 capri.bitplan.com
replacing capri.bitplan.com with the name of the server you are using. While the above ssh session is active you'll be able to point your browser to http://localhost:3030 and the Apache admin Web GUI will show and be functional.
Script to start Jena on boot
You might want to adapt the harddisk location where you keep your jena/fuseki installation and adapt the script name "fuseki" which is the script for starting Fuseki shown above.
#
# start Apache jena server
#
startJena() {
cd /hd/luxio/gnd
log=/var/log/jena.log
sudo touch $log
sudo chmod 666 $log
nohup sudo ./fuseki > /var/log/jena.log 2>&1 &
}
startJena
Apache server configuration
This configuration does not give you any access security so it's only good for small secure intranets / development environments.
#
# Apache configuration for jena.bitplan.com
# Virtual host jena
#
# see http://wiki.ubuntuusers.de/Apache/Virtual_Hosts
#
# to enable run
# a2ensite jena
# to disable run
# a2dissite jena
#
# see http://stackoverflow.com/a/13089668/1497139
#
# WF 2020-06-23 - use reverse proxy jena
<VirtualHost *:80>
ServerAdmin webmaster@bitplan.com
ServerName jena.bitplan.com
ProxyPreserveHost On
ProxyRequests Off
ProxyPass / http://localhost:3030/
ProxyPassReverse / http://localhost:3030/
</VirtualHost>Fuseki configuration
see https://stackoverflow.com/questions/63874908/fuseki-configuration
Example usecases
Get your own copy of wikidata
see Get_your_own_copy_of_WikiData
Command Line Tools
see http://www.bobdc.com/blog/jenagems/
RDF API Tutorial examples
see https://jena.apache.org/tutorials/rdf_api.html
Script to compile and run tutorial examples
#!/bin/bash
# WF 2020-06-14
num=$1
pwd=$(pwd)
base=$pwd/apache-jena-3.15.0
cd $base/src-examples
echo compiling Tutorial $num
javac -cp "$base/lib/*" jena/examples/rdf/Tutorial$num.java
echo running Tutorial $num
java -cp ".:$base/lib/*" jena/examples/rdf/Tutorial$num
Tutorial03.java
Java Code
/** Tutorial 3 Statement attribute accessor methods
*/
public class Tutorial03 extends Object {
public static void main (String args[]) {
// some definitions
String personURI = "http://somewhere/JohnSmith";
String givenName = "John";
String familyName = "Smith";
String fullName = givenName + " " + familyName;
// create an empty model
Model model = ModelFactory.createDefaultModel();
// create the resource
// and add the properties cascading style
Resource johnSmith
= model.createResource(personURI)
.addProperty(VCARD.FN, fullName)
.addProperty(VCARD.N,
model.createResource()
.addProperty(VCARD.Given, givenName)
.addProperty(VCARD.Family, familyName));
// list the statements in the graph
StmtIterator iter = model.listStatements();
// print out the predicate, subject and object of each statement
while (iter.hasNext()) {
Statement stmt = iter.nextStatement(); // get next statement
Resource subject = stmt.getSubject(); // get the subject
Property predicate = stmt.getPredicate(); // get the predicate
RDFNode object = stmt.getObject(); // get the object
System.out.print(subject.toString());
System.out.print(" " + predicate.toString() + " ");
if (object instanceof Resource) {
System.out.print(object.toString());
} else {
// object is a literal
System.out.print(" \"" + object.toString() + "\"");
}
System.out.println(" .");
}
}
}
Trying it
./ct 03
compiling Tutorial 03
running Tutorial 03
http://somewhere/JohnSmith http://www.w3.org/2001/vcard-rdf/3.0#N 7555a24e-8f13-4508-91f0-9dfb26cd2239 .
http://somewhere/JohnSmith http://www.w3.org/2001/vcard-rdf/3.0#FN "John Smith" .
7555a24e-8f13-4508-91f0-9dfb26cd2239 http://www.w3.org/2001/vcard-rdf/3.0#Family "Smith" .
7555a24e-8f13-4508-91f0-9dfb26cd2239 http://www.w3.org/2001/vcard-rdf/3.0#Given "John" .
Tutorial04.java
Java Code
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jena.examples.rdf ;
import org.apache.jena.rdf.model.*;
import org.apache.jena.vocabulary.*;
/** Tutorial 4 - create a model and write it in XML form to standard out
*/
public class Tutorial04 extends Object {
// some definitions
static String tutorialURI = "http://hostname/rdf/tutorial/";
static String briansName = "Brian McBride";
static String briansEmail1 = "brian_mcbride@hp.com";
static String briansEmail2 = "brian_mcbride@hpl.hp.com";
static String title = "An Introduction to RDF and the Jena API";
static String date = "23/01/2001";
public static void main (String args[]) {
// some definitions
String personURI = "http://somewhere/JohnSmith";
String givenName = "John";
String familyName = "Smith";
String fullName = givenName + " " + familyName;
// create an empty model
Model model = ModelFactory.createDefaultModel();
// create the resource
// and add the properties cascading style
Resource johnSmith
= model.createResource(personURI)
.addProperty(VCARD.FN, fullName)
.addProperty(VCARD.N,
model.createResource()
.addProperty(VCARD.Given, givenName)
.addProperty(VCARD.Family, familyName));
// now write the model in XML form to a file
model.write(System.out);
}
}
Trying it
./ct 04
compiling Tutorial 04
running Tutorial 04
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:vcard="http://www.w3.org/2001/vcard-rdf/3.0#">
<rdf:Description rdf:about="http://somewhere/JohnSmith">
<vcard:N rdf:parseType="Resource">
<vcard:Family>Smith</vcard:Family>
<vcard:Given>John</vcard:Given>
</vcard:N>
<vcard:FN>John Smith</vcard:FN>
</rdf:Description>
</rdf:RDF>
Tutorial05.java
Java Code
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jena.examples.rdf ;
import org.apache.jena.rdf.model.*;
import org.apache.jena.util.FileManager;
import java.io.*;
/** Tutorial 5 - read RDF XML from a file and write it to standard out
*/
public class Tutorial05 extends Object {
/**
NOTE that the file is loaded from the class-path and so requires that
the data-directory, as well as the directory containing the compiled
class, must be added to the class-path when running this and
subsequent examples.
*/
static final String inputFileName = "vc-db-1.rdf";
public static void main (String args[]) {
// create an empty model
Model model = ModelFactory.createDefaultModel();
InputStream in = FileManager.get().open( inputFileName );
if (in == null) {
throw new IllegalArgumentException( "File: " + inputFileName + " not found");
}
// read the RDF/XML file
model.read(in, "");
// write it to standard out
model.write(System.out);
}
}
Try it!
wget https://jena.apache.org/tutorials/sparql_data/vc-db-1.rdf
mv vc-db-1.rdf apache-jena-3.15.0/src-examples/
./ct 05
compiling Tutorial 05
running Tutorial 05
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:vCard="http://www.w3.org/2001/vcard-rdf/3.0#">
<rdf:Description rdf:about="http://somewhere/SarahJones">
<vCard:N rdf:parseType="Resource">
<vCard:Given>Sarah</vCard:Given>
<vCard:Family>Jones</vCard:Family>
</vCard:N>
<vCard:FN>Sarah Jones</vCard:FN>
</rdf:Description>
<rdf:Description rdf:about="http://somewhere/JohnSmith">
<vCard:N rdf:parseType="Resource">
<vCard:Given>John</vCard:Given>
<vCard:Family>Smith</vCard:Family>
</vCard:N>
<vCard:FN>John Smith</vCard:FN>
</rdf:Description>
<rdf:Description rdf:about="http://somewhere/MattJones">
<vCard:N rdf:parseType="Resource">
<vCard:Given>Matthew</vCard:Given>
<vCard:Family>Jones</vCard:Family>
</vCard:N>
<vCard:FN>Matt Jones</vCard:FN>
</rdf:Description>
<rdf:Description rdf:about="http://somewhere/RebeccaSmith">
<vCard:N rdf:parseType="Resource">
<vCard:Given>Rebecca</vCard:Given>
<vCard:Family>Smith</vCard:Family>
</vCard:N>
<vCard:FN>Becky Smith</vCard:FN>
</rdf:Description>
</rdf:RDF>
Tutorial06.java
Java Code
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jena.examples.rdf ;
import org.apache.jena.rdf.model.*;
import org.apache.jena.util.FileManager;
import org.apache.jena.vocabulary.*;
import java.io.*;
/** Tutorial navigating a model
*/
public class Tutorial06 extends Object {
static final String inputFileName = "vc-db-1.rdf";
static final String johnSmithURI = "http://somewhere/JohnSmith";
public static void main (String args[]) {
// create an empty model
Model model = ModelFactory.createDefaultModel();
// use the FileManager to find the input file
InputStream in = FileManager.get().open(inputFileName);
if (in == null) {
throw new IllegalArgumentException( "File: " + inputFileName + " not found");
}
// read the RDF/XML file
model.read(new InputStreamReader(in), "");
// retrieve the Adam Smith vcard resource from the model
Resource vcard = model.getResource(johnSmithURI);
// retrieve the value of the N property
Resource name = (Resource) vcard.getRequiredProperty(VCARD.N)
.getObject();
// retrieve the given name property
String fullName = vcard.getRequiredProperty(VCARD.FN)
.getString();
// add two nick name properties to vcard
vcard.addProperty(VCARD.NICKNAME, "Smithy")
.addProperty(VCARD.NICKNAME, "Adman");
// set up the output
System.out.println("The nicknames of \"" + fullName + "\" are:");
// list the nicknames
StmtIterator iter = vcard.listProperties(VCARD.NICKNAME);
while (iter.hasNext()) {
System.out.println(" " + iter.nextStatement().getObject()
.toString());
}
}
}
Try it!
./ct 06
compiling Tutorial 06
running Tutorial 06
The nicknames of "John Smith" are:
Adman
Smithy
Tutorial07.java
Java Code
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jena.examples.rdf ;
import org.apache.jena.rdf.model.*;
import org.apache.jena.util.FileManager;
import org.apache.jena.vocabulary.*;
import java.io.*;
/** Tutorial 7 - selecting the VCARD resources
*/
public class Tutorial07 extends Object {
static final String inputFileName = "vc-db-1.rdf";
public static void main (String args[]) {
// create an empty model
Model model = ModelFactory.createDefaultModel();
// use the FileManager to find the input file
InputStream in = FileManager.get().open(inputFileName);
if (in == null) {
throw new IllegalArgumentException( "File: " + inputFileName + " not found");
}
// read the RDF/XML file
model.read( in, "");
// select all the resources with a VCARD.FN property
ResIterator iter = model.listResourcesWithProperty(VCARD.FN);
if (iter.hasNext()) {
System.out.println("The database contains vcards for:");
while (iter.hasNext()) {
System.out.println(" " + iter.nextResource()
.getRequiredProperty(VCARD.FN)
.getString() );
}
} else {
System.out.println("No vcards were found in the database");
}
}
}
Try it !
compiling Tutorial 07
running Tutorial 07
The database contains vcards for:
Sarah Jones
John Smith
Matt Jones
Becky Smith
Tutorial08.java
Java Code
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jena.examples.rdf ;
import org.apache.jena.rdf.model.*;
import org.apache.jena.util.FileManager;
import org.apache.jena.vocabulary.*;
import java.io.*;
/** Tutorial 8 - demonstrate Selector methods
*/
public class Tutorial08 extends Object {
static final String inputFileName = "vc-db-1.rdf";
public static void main (String args[]) {
// create an empty model
Model model = ModelFactory.createDefaultModel();
// use the FileManager to find the input file
InputStream in = FileManager.get().open(inputFileName);
if (in == null) {
throw new IllegalArgumentException( "File: " + inputFileName + " not found");
}
// read the RDF/XML file
model.read( in, "" );
// select all the resources with a VCARD.FN property
// whose value ends with "Smith"
StmtIterator iter = model.listStatements(
new
SimpleSelector(null, VCARD.FN, (RDFNode) null) {
@Override
public boolean selects(Statement s) {
return s.getString().endsWith("Smith");
}
});
if (iter.hasNext()) {
System.out.println("The database contains vcards for:");
while (iter.hasNext()) {
System.out.println(" " + iter.nextStatement()
.getString());
}
} else {
System.out.println("No Smith's were found in the database");
}
}
}
Try it !
./ct 08
compiling Tutorial 08
running Tutorial 08
The database contains vcards for:
Becky Smith
John Smith