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BAEL-9120: Introduction to RDF and Apache Jena #18769

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BAEL-9120: Introduction to RDF and Apache Jena #18769

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7 changes: 7 additions & 0 deletions libraries-7/pom.xml
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Expand Up @@ -47,6 +47,12 @@
<artifactId>record-builder-core</artifactId>
<version>${record-builder.version}</version>
</dependency>
<dependency>
<groupId>org.apache.jena</groupId>
<artifactId>apache-jena-libs</artifactId>
<type>pom</type>
<version>${jena.version}</version>
</dependency>
</dependencies>

<build>
Expand Down Expand Up @@ -87,6 +93,7 @@
<yavi.version>0.14.1</yavi.version>
<manifold.version>2024.1.20</manifold.version>
<record-builder.version>47</record-builder.version>
<jena.version>5.5.0</jena.version>
</properties>

</project>
45 changes: 45 additions & 0 deletions libraries-7/src/test/java/com/baeldung/jena/ModelUnitTest.java
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package com.baeldung.jena;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;
import org.apache.jena.rdf.model.Resource;
import org.apache.jena.vocabulary.SchemaDO;
import org.junit.jupiter.api.Test;

public class ModelUnitTest {
@Test
void whenWeHaveABlogModelThenWeCanAccessTheProperties() {
Model model = ModelFactory.createDefaultModel();

{
Resource baeldung = model.createResource("/users/Baeldung")
.addProperty(SchemaDO.name, "Baeldung")
.addProperty(SchemaDO.url, "https://baeldung.com");

Resource joeBloggs = model.createResource("/users/JoeBloggs")
.addProperty(SchemaDO.name, "Joe Bloggs")
.addProperty(SchemaDO.email, "joe.bloggs@example.com");

Resource comment = model.createResource("/blog/posts/123/comments/1")
.addProperty(SchemaDO.text, "What a great article!")
.addProperty(SchemaDO.author, joeBloggs);

Resource blogPost = model.createResource("/blog/posts/123");
blogPost.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena");
blogPost.addProperty(SchemaDO.wordCount, "835");
blogPost.addProperty(SchemaDO.author, baeldung);
blogPost.addProperty(SchemaDO.comment, comment);
}

{
Resource blogPost = model.getResource("/blog/posts/123");

assertEquals("Introduction to RDF and Apache Jena", blogPost.getProperty(SchemaDO.headline).getString());

Resource author = blogPost.getProperty(SchemaDO.author).getResource();
assertEquals("Baeldung", author.getProperty(SchemaDO.name).getString());
}
}
}
49 changes: 49 additions & 0 deletions libraries-7/src/test/java/com/baeldung/jena/NTripleUnitTest.java
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package com.baeldung.jena;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;

import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFDataMgr;
import org.apache.jena.vocabulary.SchemaDO;
import org.junit.jupiter.api.Test;

public class NTripleUnitTest {
@Test
void whenWeHaveAModel_ThenWeCanSerializeAsNTriples() {
Model model = ModelFactory.createDefaultModel();

model.createResource("/blog/posts/123")
.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena")
.addProperty(SchemaDO.wordCount, "835")
.addProperty(SchemaDO.author, model.createResource("/users/Baeldung")
.addProperty(SchemaDO.name, "Baeldung")
.addProperty(SchemaDO.url, "https://baeldung.com"))
.addProperty(SchemaDO.comment, model.createResource("/blog/posts/123/comments/1")
.addProperty(SchemaDO.text, "What a great article!")
.addProperty(SchemaDO.author, model.createResource("/users/JoeBloggs")
.addProperty(SchemaDO.name, "Joe Bloggs")
.addProperty(SchemaDO.email, "joe.bloggs@example.com")));

ByteArrayOutputStream out = new ByteArrayOutputStream();
RDFDataMgr.write(out, model, Lang.NTRIPLES);

assertEquals("""
</blog/posts/123/comments/1> <https://schema.org/author> </users/JoeBloggs> .
</blog/posts/123/comments/1> <https://schema.org/text> "What a great article!" .
</users/Baeldung> <https://schema.org/url> "https://baeldung.com" .
</users/Baeldung> <https://schema.org/name> "Baeldung" .
</users/JoeBloggs> <https://schema.org/email> "joe.bloggs@example.com" .
</users/JoeBloggs> <https://schema.org/name> "Joe Bloggs" .
</blog/posts/123> <https://schema.org/comment> </blog/posts/123/comments/1> .
</blog/posts/123> <https://schema.org/author> </users/Baeldung> .
</blog/posts/123> <https://schema.org/wordCount> "835" .
</blog/posts/123> <https://schema.org/headline> "Introduction to RDF and Apache Jena" .
""", out.toString());
}
}
154 changes: 154 additions & 0 deletions libraries-7/src/test/java/com/baeldung/jena/RDFXMLUnitTest.java
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package com.baeldung.jena;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.io.ByteArrayOutputStream;
import java.io.StringReader;

import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;
import org.apache.jena.rdf.model.Resource;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFDataMgr;
import org.apache.jena.vocabulary.SchemaDO;
import org.junit.jupiter.api.Test;

public class RDFXMLUnitTest {
@Test
void whenWeHaveAModel_ThenWeCanSerializeAsRDFXMLUsingRDFDataMgr() {
Model model = ModelFactory.createDefaultModel();

model.createResource("tag:baeldung:/blog/posts/123")
.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena")
.addProperty(SchemaDO.wordCount, "835")
.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/Baeldung")
.addProperty(SchemaDO.name, "Baeldung")
.addProperty(SchemaDO.url, "https://baeldung.com"))
.addProperty(SchemaDO.comment, model.createResource("tag:baeldung:/blog/posts/123/comments/1")
.addProperty(SchemaDO.text, "What a great article!")
.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/JoeBloggs")
.addProperty(SchemaDO.name, "Joe Bloggs")
.addProperty(SchemaDO.email, "joe.bloggs@example.com")));

ByteArrayOutputStream out = new ByteArrayOutputStream();
RDFDataMgr.write(out, model, Lang.RDFXML);

assertEquals("""
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:j.0="https://schema.org/">
<rdf:Description rdf:about="tag:baeldung:/blog/posts/123">
<j.0:comment>
<rdf:Description rdf:about="tag:baeldung:/blog/posts/123/comments/1">
<j.0:author>
<rdf:Description rdf:about="tag:baeldung:/users/JoeBloggs">
<j.0:email>joe.bloggs@example.com</j.0:email>
<j.0:name>Joe Bloggs</j.0:name>
</rdf:Description>
</j.0:author>
<j.0:text>What a great article!</j.0:text>
</rdf:Description>
</j.0:comment>
<j.0:author>
<rdf:Description rdf:about="tag:baeldung:/users/Baeldung">
<j.0:url>https://baeldung.com</j.0:url>
<j.0:name>Baeldung</j.0:name>
</rdf:Description>
</j.0:author>
<j.0:wordCount>835</j.0:wordCount>
<j.0:headline>Introduction to RDF and Apache Jena</j.0:headline>
</rdf:Description>
</rdf:RDF>
""", out.toString());
}

@Test
void whenWeHaveAModel_ThenWeCanSerializeAsRDFXMLUsingWrite() {
Model model = ModelFactory.createDefaultModel();

model.createResource("tag:baeldung:/blog/posts/123")
.addProperty(SchemaDO.headline, "Introduction to RDF and Apache Jena")
.addProperty(SchemaDO.wordCount, "835")
.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/Baeldung")
.addProperty(SchemaDO.name, "Baeldung")
.addProperty(SchemaDO.url, "https://baeldung.com"))
.addProperty(SchemaDO.comment, model.createResource("tag:baeldung:/blog/posts/123/comments/1")
.addProperty(SchemaDO.text, "What a great article!")
.addProperty(SchemaDO.author, model.createResource("tag:baeldung:/users/JoeBloggs")
.addProperty(SchemaDO.name, "Joe Bloggs")
.addProperty(SchemaDO.email, "joe.bloggs@example.com")));

ByteArrayOutputStream out = new ByteArrayOutputStream();
model.write(out);

assertEquals("""
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:j.0="https://schema.org/">
<rdf:Description rdf:about="tag:baeldung:/blog/posts/123">
<j.0:comment>
<rdf:Description rdf:about="tag:baeldung:/blog/posts/123/comments/1">
<j.0:author>
<rdf:Description rdf:about="tag:baeldung:/users/JoeBloggs">
<j.0:email>joe.bloggs@example.com</j.0:email>
<j.0:name>Joe Bloggs</j.0:name>
</rdf:Description>
</j.0:author>
<j.0:text>What a great article!</j.0:text>
</rdf:Description>
</j.0:comment>
<j.0:author>
<rdf:Description rdf:about="tag:baeldung:/users/Baeldung">
<j.0:url>https://baeldung.com</j.0:url>
<j.0:name>Baeldung</j.0:name>
</rdf:Description>
</j.0:author>
<j.0:wordCount>835</j.0:wordCount>
<j.0:headline>Introduction to RDF and Apache Jena</j.0:headline>
</rdf:Description>
</rdf:RDF>
""", out.toString());
}

@Test
void whenWeHaveRDFXML_thenWeCanParseThis() {
String rdfxml = """
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:j.0="https://schema.org/">
<rdf:Description rdf:about="tag:baeldung:/blog/posts/123">
<j.0:comment>
<rdf:Description rdf:about="tag:baeldung:/blog/posts/123/comments/1">
<j.0:author>
<rdf:Description rdf:about="tag:baeldung:/users/JoeBloggs">
<j.0:email>joe.bloggs@example.com</j.0:email>
<j.0:name>Joe Bloggs</j.0:name>
</rdf:Description>
</j.0:author>
<j.0:text>What a great article!</j.0:text>
</rdf:Description>
</j.0:comment>
<j.0:author>
<rdf:Description rdf:about="tag:baeldung:/users/Baeldung">
<j.0:url>https://baeldung.com</j.0:url>
<j.0:name>Baeldung</j.0:name>
</rdf:Description>
</j.0:author>
<j.0:wordCount>835</j.0:wordCount>
<j.0:headline>Introduction to RDF and Apache Jena</j.0:headline>
</rdf:Description>
</rdf:RDF>
""";

Model model = ModelFactory.createDefaultModel();
model.read(new StringReader(rdfxml), null);

Resource blogPost = model.getResource("tag:baeldung:/blog/posts/123");

assertEquals("Introduction to RDF and Apache Jena", blogPost.getProperty(SchemaDO.headline).getString());

Resource author = blogPost.getProperty(SchemaDO.author).getResource();
assertEquals("Baeldung", author.getProperty(SchemaDO.name).getString());

}
}