DynamoDB with the AWS SDK for Java 2.x

Uses software.amazon.awssdk:dynamodb 2.57 with endpointOverride. The code is an ordinary application for the original database; nothing in it knows about MachNoSQL.

The only change

https://dynamodb.eu-central-1.amazonaws.com
https://machnosql.example.com:8000

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

Run

export DYNAMODB_ENDPOINT='https://machnosql.example.com:8000'
mvn -q compile exec:java

Credentials are the usual AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY (an access key created in MachNoSQL) and AWS_REGION. Instead of passing the endpoint in code, current AWS SDKs and the AWS CLI also read AWS_ENDPOINT_URL_DYNAMODB from the environment; then the application needs no change at all.

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

// Orders table on DynamoDB, unchanged on MachNoSQL.
package example;

import java.net.URI;
import java.util.Map;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.DynamoDbClientBuilder;
import software.amazon.awssdk.services.dynamodb.model.AttributeDefinition;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.BillingMode;
import software.amazon.awssdk.services.dynamodb.model.KeySchemaElement;
import software.amazon.awssdk.services.dynamodb.model.KeyType;
import software.amazon.awssdk.services.dynamodb.model.ResourceInUseException;
import software.amazon.awssdk.services.dynamodb.model.ScalarAttributeType;

public final class App {
    private static AttributeValue s(String value) {
        return AttributeValue.fromS(value);
    }

    public static void main(String[] args) {
        DynamoDbClientBuilder builder = DynamoDbClient.builder();
        String endpoint = System.getenv("DYNAMODB_ENDPOINT");
        if (endpoint != null) {
            builder.endpointOverride(URI.create(endpoint));
        }
        try (DynamoDbClient ddb = builder.build()) {
            try {
                ddb.createTable(t -> t.tableName("Orders")
                    .keySchema(
                        KeySchemaElement.builder().attributeName("customer").keyType(KeyType.HASH).build(),
                        KeySchemaElement.builder().attributeName("orderId").keyType(KeyType.RANGE).build())
                    .attributeDefinitions(
                        AttributeDefinition.builder().attributeName("customer").attributeType(ScalarAttributeType.S).build(),
                        AttributeDefinition.builder().attributeName("orderId").attributeType(ScalarAttributeType.S).build())
                    .billingMode(BillingMode.PAY_PER_REQUEST));
                ddb.waiter().waitUntilTableExists(r -> r.tableName("Orders"));
            } catch (ResourceInUseException alreadyThere) {
                // The table exists from an earlier run.
            }

            ddb.putItem(p -> p.tableName("Orders").item(Map.of(
                "customer", s("ada"), "orderId", s("1001"), "item", s("keyboard"), "total", AttributeValue.fromN("49"))));
            ddb.putItem(p -> p.tableName("Orders").item(Map.of(
                "customer", s("ada"), "orderId", s("1002"), "item", s("mouse"), "total", AttributeValue.fromN("39"))));

            System.out.println(ddb.getItem(g -> g.tableName("Orders")
                .key(Map.of("customer", s("ada"), "orderId", s("1001")))).item());

            System.out.println(ddb.query(q -> q.tableName("Orders")
                .keyConditionExpression("customer = :c")
                .expressionAttributeValues(Map.of(":c", s("ada")))).items());

            ddb.updateItem(u -> u.tableName("Orders")
                .key(Map.of("customer", s("ada"), "orderId", s("1002")))
                .updateExpression("SET #s = :shipped")
                .conditionExpression("attribute_not_exists(#s)")
                .expressionAttributeNames(Map.of("#s", "status"))
                .expressionAttributeValues(Map.of(":shipped", s("shipped"))));
        }
    }
}

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>dynamodb-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>software.amazon.awssdk</groupId>
      <artifactId>dynamodb</artifactId>
      <version>2.57.7</version>
    </dependency>
  </dependencies>
</project>