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SPARQL tutorial by

Ciro Santilli 40 Updated 2025-07-16

In this tutorial, we will use the Jena SPARQL hello world as a starting point. Tested on Apache Jena 4.10.0.

Basic query on rdf/vcard.ttl RDF Turtle data to find the person with full name "John Smith":

sparql --data=rdf/vcard.ttl --query=<( printf '%s\n' 'SELECT ?x WHERE { ?x <http://www.w3.org/2001/vcard-rdf/3.0#FN> "John Smith" }')

Output:

---------------------------------
| x                             |
=================================
| <http://somewhere/JohnSmith/> |
---------------------------------

To avoid writing http://www.w3.org/2001/vcard-rdf/3.0# a billion times as queries grow larger, we can use the PREFIX syntax:

sparql --data=rdf/vcard.ttl --query=<( printf '%s\n' '
PREFIX vc: <http://www.w3.org/2001/vcard-rdf/3.0#>
SELECT ?x
WHERE { ?x vc:FN "John Smith" }
')

Output:

---------------------------------
| x                             |
=================================
| <http://somewhere/JohnSmith/> |
---------------------------------

Bibliography:

UniProt contains some amazing examples runnable on their servers: sparql.uniprot.org/.well-known/sparql-examples/

SPARQL implementation by

Ciro Santilli 40 Updated 2025-07-16

Ciro Santilli's knee by

Ciro Santilli 40 Updated 2025-07-16

If Achilles' had his heel, Ciro had his knee.

First during University in Brazil while trying a kick up during the development of Cirodance his knee went a bit weird for a few weeks.

Then, just after arriving in France for École Polytechnique, the boys were playing indoor soccer, and to impress the girls Ciro was playing really hard, even took off his shirt, and suddenly when he was running by himself his knee snapped, he fell and it hurt like hell.

Ciro was on crutches for a few weeks, but the inflammation went away, but then he tried to play more soccer, but the knee was not as stable as before, and once he tried to run full speed, it slipped and hurt him a bit more (less severely) and so he gave up. For some reason it was not visible on the tomography made at the hospital.

Maybe Ciro should have investigated more though, certainly an experienced doctor could have done a hand pressure exam to determine which joint was damaged manually even. That was a medical failure.

So from this day on Ciro gave up on all interesting sports, and confined himself to more repetitive stuff like gym weights and cycling: Section "Ciro Santilli's sport practice". At Polytechnique he was forced to take up swimming as his mandatory sport, that was unbearably boring.

This defect is likely genetic since a close relative had similar problems.

But oh well, his then not-even girlfriend was impressed enough by the soccer or sorry enough for the sucker to marry him, so it worked out.

Apache Jena by

Ciro Santilli 40 Updated 2025-07-16

Bibliography:

www.reddit.com/r/semanticweb/comments/131wzn1/whats_the_best_way_to_work_with_apache_jena/

Apache Jena CLI tools setup by

Ciro Santilli 40 Updated 2025-07-16

as per: users.jena.apache.narkive.com/T5TaEszT/sparql-tutorial-querying-datasets-error-unrecognized-option-graph

The CLI tools don't appear to be packaged for Ubuntu 23.10? Annoying... There is a package libapache-jena-java but it doesn't contain any binaries, only Java library files.

To run the CLI tools easily we can download the prebuilt:

sudo apt install openjdk-22-jre
wget https://dlcdn.apache.org/jena/binaries/apache-jena-4.10.0.zip
unzip apache-jena-4.10.0.zip
cd apache-jena-4.10.0
export JENA_HOME="$(pwd)"
export PATH="$PATH:$(pwd)/bin"

and we can confirm it works with:

sparql -version

which outputs:

Apache Jena version 4.10.0

If your Java is too old then then running sparql with the prebuilts fails with:

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.UnsupportedClassVersionError: arq/sparql has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:756)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:473)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:74)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:369)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:363)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:362)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:621)

Build from source is likely something like:

sudo apt install maven openjdk-22-jdk
git clone https://github.com/apache/jena --branch jena-4.10.0 --depth 1
cd jena
mvn clean install

TODO test it.

If you make the mistake of trying to run the source tree without build:

git clone https://github.com/apache/jena --branch jena-4.10.0 --depth 1
cd jena
export JENA_HOME="$(pwd)"
export PATH="$PATH:$(pwd)/apache-jena/bin"

it fails with:

Error: Could not find or load main class arq.sparql

Psychology by

Ciro Santilli 40 Updated 2025-07-16

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