Neo4j with the Java driver

Uses neo4j-java-driver 6.3. The code is an ordinary application for the original database; nothing in it knows about MachNoSQL.

The only change

neo4j://neo4j.example.com:7687
neo4j://machnosql.example.com:7687

The address comes from the environment variable NEO4J_URI, so switching to MachNoSQL changes configuration only.

Run

export NEO4J_URI='neo4j://machnosql.example.com:7687'
mvn -q compile exec:java

Credentials come from NEO4J_USERNAME and NEO4J_PASSWORD.

Source

The program as it is kept and tested in the Mach Database NoSQL repository; highlighted lines read the connection setting.

src/main/java/example/App.java

// Friends of friends on Neo4j, unchanged on MachNoSQL.
package example;

import java.util.List;
import java.util.Map;
import org.neo4j.driver.AuthTokens;
import org.neo4j.driver.Driver;
import org.neo4j.driver.GraphDatabase;

public final class App {
    public static void main(String[] args) {
        var auth = AuthTokens.basic(System.getenv("NEO4J_USERNAME"), System.getenv("NEO4J_PASSWORD"));
        try (Driver driver = GraphDatabase.driver(System.getenv("NEO4J_URI"), auth)) {
            driver.verifyConnectivity();

            var pairs = List.of(List.of("ada", "grace"), List.of("grace", "linus"),
                List.of("grace", "margaret"), List.of("linus", "ken"));
            driver.executableQuery("UNWIND $pairs AS pair MERGE (a:Person {name: pair[0]}) MERGE (b:Person {name: pair[1]}) MERGE (a)-[:KNOWS]->(b)")
                .withParameters(Map.of("pairs", pairs))
                .execute();

            var result = driver.executableQuery("MATCH (p:Person {name: $name})-[:KNOWS]->()-[:KNOWS]->(fof) WHERE fof <> p RETURN DISTINCT fof.name AS name ORDER BY name")
                .withParameters(Map.of("name", "ada"))
                .execute();
            result.records().forEach(record -> System.out.println(record.get("name").asString()));
        }
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example.machnosql</groupId>
  <artifactId>neo4j-example</artifactId>
  <version>1.0</version>
  <properties>
    <maven.compiler.release>21</maven.compiler.release>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <exec.mainClass>example.App</exec.mainClass>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.neo4j.driver</groupId>
      <artifactId>neo4j-java-driver</artifactId>
      <version>6.3.0</version>
    </dependency>
  </dependencies>
</project>