Redis with Lettuce (Java)

Uses Lettuce 7.9. The code is an ordinary application for the original database; nothing in it knows about MachNoSQL.

The only change

redis://:secret@redis.example.com:6379/0
redis://:secret@machnosql.example.com:6379/0

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

Run

export REDIS_URL='redis://:secret@machnosql.example.com:6379/0'
mvn -q compile exec:java

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

// Cache, counter, session and leaderboard on Redis, unchanged on MachNoSQL.
package example;

import io.lettuce.core.RedisClient;
import io.lettuce.core.ScoredValue;
import io.lettuce.core.SetArgs;
import io.lettuce.core.api.StatefulRedisConnection;
import io.lettuce.core.api.sync.RedisCommands;
import java.util.Map;

public final class App {
    public static void main(String[] args) {
        RedisClient client = RedisClient.create(System.getenv("REDIS_URL"));
        try (StatefulRedisConnection<String, String> connection = client.connect()) {
            RedisCommands<String, String> redis = connection.sync();

            redis.set("cache:home", "<html>...</html>", SetArgs.Builder.ex(60));
            System.out.println("cached: " + redis.get("cache:home") + " ttl: " + redis.ttl("cache:home"));

            System.out.println("views: " + redis.incr("views:home"));

            redis.hset("session:42", Map.of("user", "ada", "cart_items", "3"));
            System.out.println("session: " + redis.hgetall("session:42"));

            redis.zadd("leaderboard", ScoredValue.just(120, "ada"), ScoredValue.just(95, "linus"),
                ScoredValue.just(130, "grace"));
            System.out.println("top: " + redis.zrevrangeWithScores("leaderboard", 0, 2));

            redis.multi();
            redis.incr("orders:count");
            redis.lpush("orders:recent", "order-1001");
            redis.ltrim("orders:recent", 0, 99);
            System.out.println("pipeline: " + redis.exec());
        } finally {
            client.shutdown();
        }
    }
}

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>redis-lettuce-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>io.lettuce</groupId>
      <artifactId>lettuce-core</artifactId>
      <version>7.9.0.RELEASE</version>
    </dependency>
  </dependencies>
</project>