I am using Amazon Neptune for my application. So I want to know if there is a way to use Spring Boot (Java) to connect and use data from queries in Neptune workbench for my app. I have successfully connected to Neptune database using Java core with Visual Studio Code but I can't find any documentation that clearly describes this procedure for Spring Boot. Can some help me in this case? Thanks in advance!

CodePudding user response：

To use Neptune with springboot you have to add the configuration file like this below.

@Configuration
public class NeptuneConfigExample {


@Bean
public Cluster cluster() {
    return Cluster.build()
            .addContactPoint("your-neptune-instance-here.xxxxxxxxxxxx.us-east-1.neptune.amazonaws.com")
            .port(8182)
            .enableSsl(true)
            .keyCertChainFile("./cert/SFSRootCAG2.pem") // download it from https://www.amazontrust.com/repository/SFSRootCAG2.pem 
            .maxConnectionPoolSize(5)
            .maxInProcessPerConnection(1)
            .maxSimultaneousUsagePerConnection(1)
            .create();
    }
}

For reference - click

CodePudding user response：

To connect to Neptune

Install Apache Maven on your EC2 instance. First, enter the following to add a repository with a Maven package:

sudo wget https://repos.fedorapeople.org/repos/dchen/apache- 
maven/epel-apache-maven.repo -O /etc/yum.repos.d/epel-apache- 
maven.repo

Enter the following to set the version number for the packages:

sudo sed -i s/\$releasever/6/g /etc/yum.repos.d/epel-apache- 
maven.repo

Then you can use yum to install Maven:

 sudo yum install -y apache-maven

This example was tested with Java 8 only. Enter the following to install Java 8 on your EC2 instance:

sudo yum install java-1.8.0-devel

Enter the following to set Java 8 as the default runtime on your EC2 instance:

sudo /usr/sbin/alternatives --config java

When prompted, enter the number for Java 8.

Enter the following to set Java 8 as the default compiler on your EC2 instance:

sudo /usr/sbin/alternatives --config javac

When prompted, enter the number for Java 8.

In a new directory, create a pom.xml file, and then open it in a text editor.

Copy the following into the pom.xml file and save it (you can usually adjust the version numbers to the latest stable version):

<project xmlns="https://maven.apache.org/POM/4.0.0" 
xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 
 https://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
 <groupId>com.amazonaws</groupId>
 <artifactId>RDFExample</artifactId>
<packaging>jar</packaging>
 <version>1.0-SNAPSHOT</version>
<name>RDFExample</name>
<url>https://maven.apache.org</url>
<dependencies>
<dependency>
  <groupId>org.eclipse.rdf4j</groupId>
  <artifactId>rdf4j-runtime</artifactId>
  <version>3.6</version>
 </dependency>
 </dependencies>
 <build>
<plugins>
  <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>exec-maven-plugin</artifactId>
      <version>1.2.1</version>
      <configuration>
        <mainClass>com.amazonaws.App</mainClass>
      </configuration>
  </plugin>
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
      <source>1.8</source>
      <target>1.8</target>
       </configuration>
      </plugin>
    </plugins>
    </build>
 </project>    

Note If you are modifying an existing Maven project, the required dependency is highlighted in the preceding code.

To create subdirectories for the example source code (src/main/java/com/amazonaws/), enter the following at the command line:

mkdir -p src/main/java/com/amazonaws/

In the src/main/java/com/amazonaws/ directory, create a file named App.java, and then open it in a text editor.

Copy the following into the App.java file. Replace your-neptune-endpoint with the address of your Neptune DB instance.

package com.amazonaws;

import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.http.HTTPRepository;
import org.eclipse.rdf4j.repository.sparql.SPARQLRepository;

import java.util.List;
import org.eclipse.rdf4j.RDF4JException;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.model.Value;

public class App
{
public static void main( String[] args )
{
    String sparqlEndpoint = "https://your-neptune- 
  endpoint:port/sparql";
    Repository repo = new SPARQLRepository(sparqlEndpoint);
    repo.initialize();

    try (RepositoryConnection conn = repo.getConnection()) {
       String queryString = "SELECT ?s ?p ?o WHERE { ?s ?p ?o } 
    limit 10";

       TupleQuery tupleQuery = 
 conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);

       try (TupleQueryResult result = tupleQuery.evaluate()) {
          while (result.hasNext()) {  // iterate over the result
               BindingSet bindingSet = result.next();

               Value s = bindingSet.getValue("s");
               Value p = bindingSet.getValue("p");
               Value o = bindingSet.getValue("o");

               System.out.print(s);
               System.out.print("\t");
               System.out.print(p);
               System.out.print("\t");
               System.out.println(o);
          }
       }
    }
}
}

Use the following Maven command to compile and run the sample:

 mvn compile exec:java