Apache Commons RDF

Commons RDF aims to provide a common library for RDF 1.1 with implementations for common Java RDF frameworks like RDF4J, Apache Jena as well as for other libraries such as OWLAPI, Clerezza and other JVM languages.

The main motivation behind this simple library is to revise an historical incompatibility issue between these toolkits. This library does not pretend to be a generic API wrapping those libraries, but is a set of common Java interfaces for the RDF 1.1 concepts, e.g. IRI, BlankNode, Graph, accompanied with unit test cases for their expected behavior, and a simple implementation, which main purpose is to clarify the tests and interfaces.

In particular, Commons RDF aims to provide a type-safe, non-general API that covers RDF 1.1.

A diagram of the interfaces included in Commons RDF:

Everybody is welcomed to join the project and contribute!

See the Commons RDF homepage for more details.

License

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

https://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.

Contributing

Feel free to subscribe to the dev@commons mailing list, use the Subject tag [RDF] to follow the ongoing development of Commons RDF, ask questions about its usage, or help shape Commons RDF by contributing your ideas, code and use cases.

Building

Building has been tested with Apache Maven 3 and Java 11 and up.

$ mvn
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO] 
[INFO] Commons RDF
[INFO] Commons RDF: API
[INFO] Commons RDF: Simple impl
[INFO] 
[INFO] Using the builder org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder with a thread count of 1
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building Commons RDF 0.5.0
    ....
[INFO] Installing /home/johndoe/src/commons-rdf/commons-rdf-api/target/commons-rdf-api-0.5.0-javadoc.jar to /home/johndoe/.m2/repository/org/apache/commons/commons-rdf/commons-rdf-api/0.5.0/commons-rdf-api-0.5.0-javadoc.jar
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary:
[INFO] 
[INFO] Commons RDF ........................................ SUCCESS [  0.404 s]
[INFO] Commons RDF: API ................................... SUCCESS [  0.031 s]
[INFO] Commons RDF: Simple Implementation ................. SUCCESS [  0.010 s]
[INFO] Commons RDF: Integration: RDF4j .................... SUCCESS [  0.012 s]
[INFO] Commons RDF: Integration: Apache Jena .............. SUCCESS [  0.011 s]
[INFO] Commons RDF: Integration: JSON-LD Java ............. SUCCESS [  0.009 s]
[INFO] Commons RDF: Integration tests ..................... SUCCESS [  0.005 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 7.718 s
[INFO] Finished at: 2015-01-26T02:09:10+00:00
[INFO] Final Memory: 22M/309M
[INFO] ------------------------------------------------------------------------

To then use this build from your project, add to Maven (update <version> to match the Maven output):

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-rdf-api</artifactId>
    <version>0.5.0</version>
</dependency>

.. and an equivalent <dependency> for the implementation you would like, e.g. commons-rdf-simple.

The <version> above might not be up to date, see the downloads to use the latest stable release published in Maven Central.

Snapshot repository

The Apache Commons RDF project is aiming to regularly release early previews releases (0.x.y versions) and publish these to Maven Central. See the downloads to use the latest stable release.

However, if you are following the ongoing development on dev@commons, (using subject tag [RDF]) you may want to try the snapshot builds, which are automatically deployed to the Apache snapshot repository.

To use these snapshots from your Maven project, depend on the latest *-SNAPSHOT version as found in the current pom.xml, and add to your own pom.xml:

<repositories>
  <repository>
    <id>apache.snapshots</id>
    <name>Apache Snapshot Repository</name>
    <url>http://repository.apache.org/snapshots</url>
    <releases>
      <enabled>false</enabled>
    </releases>
  </repository>
</repositories>

Simple implementation

The commons-rdf-simple module contains a simple (if not naive) implementation of the Commons RDF API using in-memory POJO objects.

Note that although this module fully implements the commons-rdf API, it should not be considered a reference implementation. It is not thread-safe nor scalable, but may be useful for testing and simple usage (e.g. output from an independent RDF parser).

Testing

The abstract classes AbstractGraphTest, AbstractDatasetTest, AbstractBlankNodeTest and AbstractRDFTest can be realised as JUnit tests by implementations in order to verify that they pass the minimal requirements of this API.

In order for this to work, your project will need to depend on the tests classifier for the commons-rdf-api module, for example (for Maven):

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-rdf-api</artifactId>
    <version>0.5.0</version>
    <classifier>tests</classifier>
    <scope>test</scope>
</dependency>

The extensions of each Test class need to provide a RDF instance that can create the corresponding implementations of a Graph, IRI, etc.

For an example, see SimpleGraphTest.