Elasticsearch with the Java API client

Uses elasticsearch-java 9.5. The code is an ordinary application for the original database; nothing in it knows about MachNoSQL.

The only change

https://es.example.com:9200
https://machnosql.example.com:9200

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

Run

export ELASTICSEARCH_URL='https://machnosql.example.com:9200'
mvn -q compile exec:java

Credentials come from ELASTICSEARCH_USERNAME and ELASTICSEARCH_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

// Product search on Elasticsearch, unchanged on MachNoSQL.
package example;

import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.elasticsearch._types.Refresh;
import co.elastic.clients.elasticsearch.core.SearchResponse;
import co.elastic.clients.elasticsearch.core.search.Hit;
import java.io.IOException;
import java.util.List;

public final class App {
    public record Product(String name, String brand, double price) {}

    public static void main(String[] args) throws IOException {
        try (ElasticsearchClient es = ElasticsearchClient.of(b -> b
                .host(System.getenv("ELASTICSEARCH_URL"))
                .usernameAndPassword(System.getenv("ELASTICSEARCH_USERNAME"), System.getenv("ELASTICSEARCH_PASSWORD")))) {

            if (!es.indices().exists(e -> e.index("products")).value()) {
                es.indices().create(c -> c.index("products").mappings(m -> m
                    .properties("name", p -> p.text(t -> t))
                    .properties("brand", p -> p.keyword(k -> k))
                    .properties("price", p -> p.float_(f -> f))));
            }

            List<Product> products = List.of(
                new Product("mechanical keyboard", "keyco", 89.0),
                new Product("wireless keyboard", "typer", 49.0),
                new Product("gaming mouse", "keyco", 39.0));
            for (int i = 0; i < products.size(); i++) {
                String id = String.valueOf(i + 1);
                Product product = products.get(i);
                es.index(x -> x.index("products").id(id).document(product).refresh(Refresh.True));
            }

            SearchResponse<Product> found = es.search(s -> s.index("products")
                .query(q -> q.match(m -> m.field("name").query("keyboard")))
                .aggregations("brands", a -> a.terms(t -> t.field("brand"))), Product.class);
            for (Hit<Product> hit : found.hits().hits()) {
                System.out.println(hit.score() + " " + hit.source().name());
            }
            System.out.println(found.aggregations().get("brands").sterms().buckets().array());
        }
    }
}

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>elasticsearch-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>co.elastic.clients</groupId>
      <artifactId>elasticsearch-java</artifactId>
      <version>9.5.5</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.22.4</version>
    </dependency>
  </dependencies>
</project>