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nora's Introduction

NORA: Scalable OWL reasoner based on NoSQL databases and Apache Spark

License: MIT

Tested with OpenJDK 11 and Gradle 7.5.1.

Cite us:

Benítez-Hidalgo A, Navas-Delgado I, Roldán-García MM. NORA: Scalable OWL reasoner based on NoSQL databases and Apache Spark. Softw Pract Exper. 2023; 53(12): 2377–2392. doi: 10.1002/spe.3258

Building the project

Use gradle to build the project:

$ make build

Getting started

Before running the project, edit the config.properties and set your own values. Make sure to set the NORA_CONFIG environment variable to the path of the config.properties file:

$ export NORA_CONFIG=$(pwd)/config.properties

Load the ontology into the database:

$ java -cp nora.jar loader.Loader examples/ontology.owl examples/individuals/ http://w3id.org/examples/ontology.owl

Then, start the reasoning process by running the following command:

$ java -cp nora.jar reasoner.Reasoner

or by using spark-submit:

$ spark-submit \
    --name nora \
    --class reasoner.Reasoner \
    --master spark://host:port \
    --driver-memory 6G \
    --executor-memory 120G \
    file:///home/user/nora.jar 10

A step-by-step guide is available in the docs directory.

Troubleshooting

Exception java.lang.OutOfMemoryError: Java heap space when running Apache Spark in client mode

The flag -Xmx specifies the maximum memory allocation pool for a Java Virtual Machine (JVM), while -Xms specifies the initial memory allocation pool. These flags can be set to modify the Java memory settings:

  • IntelliJ IDEA: Run/Debug configuration > Set VM options to -Xms10g -Xmx80g
  • Terminal: Run Java with -Xms10g -Xmx80g

Tests

Run the following command to run the tests:

$ make test

Embedded Cassandra requires JDK 11 or lower. If using a higher version, downgrade it to JDK 11.

License

This project is licensed under the MIT license - see the LICENSE file for details.

nora's People

Contributors

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nora's Issues

Need help with installation/setup

I am conducting a survey about OWL reasoners still useable in 2023 and would like to try this reasoner out. My Java knowledge is very limited and I have a hard time even setting this reasoner up:

  1. Running make build resulted in make: ./gradlew: Command not found error (OpenJDK 11 is installed, Gradle too)
  2. I assume spark-submit is part of Apache Spark or is that something else?
  3. What configuration options are required to set? Is it possible to provide some very basic test files?

You are using a jar-file at some point, could you provide it as a download (so I can skip the building part)? A docker setup with everything in it would also be helpful.

Thanks in advance

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