Java Nats Server

Nats Server for testing which contains the original Nats

Index

• Variants
• Configuration Properties
• Configuration Priority Order
• Java Common Methods
• Examples
  • Java-Nats-Server
  • Java-Nats-Server (JUnit)
  • Java-Nats-Server (Spring)
  • Java-Nats-Streaming-Server (deprecation-notice)
  • Java-Nats-Streaming-Server (Spring) (deprecation-notice)

Variants

Repositories	Framework	Maven Central	Contains
Java-Nats-Server	Plain Java		Original Nats Server
Java-Nats-Server-JUnit	JUnit 5		Java-Nats-Server
Java-Nats-Server-Embedded	Spring Boot		Java-Nats-Server
Java-Nats-Streaming-Server	Plain Java		Original Nats Streaming Server (deprecation-notice)
Java-Nats-Streaming-Server-Embedded	Spring Boot		Java-Nats-Streaming-Server (deprecation-notice)

Configuration properties

• Configs can be found under NatsConfig or NatsStreamingConfig
  • The available config keys are based on the default NATS_VERSION version of the current artefact
• The properties must start with the prefix NATS_ (e.g NATS_CLUSTER_ID)
• nats.properties can be created optionally to configure the Nats Server

Configuration priority

1) Custom Arguments 2) Java DSL config 3) Property File (default nats.properties) 4) Environment Variables (*1) 5) Default Config

Common methods

Getter

Name	Description
url	nats server URL from bind to host address
pid	process id (-1 == not started)
port	port (-1 == not started && random port)
debug	true if “DV”, “DVV” or “DEBUG” is set
version	version of nats server
config	Get config map
binary	Path to binary file
pidFile	Path to PID file
getValue	Get resolved config for a key
jetstream	true if Jetstream is enabled
configFile	custom nats config file
downloadUrl	Download URL
configPropertyFile	custom property config file

Others

Name	Description
start()	Starts the nats server
close()	Stops the nats server

Java Nats Example

• Java Nats:
• Java Streaming Nats:
  • Deprecation Notice

Example auto closable

public class MyNatsTest {

    public static void main(final String[] args) {
        try (final var nats = new Nats()) {
            //DO SOMETHING...
        }
    }
}

Example with diverse configs

• Nats has more than 50 configs are available
• NatsStreaming has more than 90 configs are available
• Nats Steaming: classes and methods uses suffix Streaming e.g. NatsStreaming

public class MyNatsTest {

    public static void main(final String[] args) {
        final Nats nats = natsBuilder()
                .port(-1)
                .debug(false)
                .jetStream(true)
                .autostart(true)
                .timeoutMs(10000)
                .version("3.0.0")
                .version(NatsVersion.V3_0_0)
                .configFile("/etc/usr/nats/nats.cfg")
                .configPropertyFile("/etc/usr/nats/nats.properties")
                .customArgs("--optionalArg1=123", "--optionalArg2=456")
                .logger(Logger.getLogger("MyCustomLogger"))
                .logLevel(System.Logger.Level.DEBUG)
                .config(USER, "my_optional_user")
                .config(PASS, "my_optional_password")
                .config(
                        NATS_BINARY_PATH.toString(), "optional/ready/to/use/nats/file",
                        NATS_DOWNLOAD_URL.toString(), "optional/nats/download/url",
                        NATS_CONFIG_FILE.toString(), "optional/config/file",
                        NATS_ARGS.toString(), "--optionalArg1=123 && --optionalArg2=456",
                        NATS_SYSTEM.toString(), "optional_download_suffix"
                ).nats();
        nats.close();
    }
}

Java Nats JUnit Example

• Port -1 = random port
• keepAlive = nats starts only one time in the whole test context

@JUnitNatsServer(
        port = 4680,
        keepAlive = true,
        timeoutMs = 10000,
        version = "3.0.0",
        configFile = "my.properties",
        downloadUrl = "https://example.com",
        binaryFile = "/tmp/natsserver",
        config = {"ADDR", "localhost"}
)
class NatsServerFirstTest {

    final NatsServer natsServer = getNatsServer();

    @Test
    void natsServerShouldStart() {
        assertThat(natsServer, is(notNullValue()));
    }
}

Java Nats Spring Example

• Supports spring config
• Configuration Properties are overwriting the spring properties

@SpringBootTest
@RunWith(SpringRunner.class)
@EnableNatsServer(port = 4222, config = {"user", "admin", "pass", "admin"})
public class SomeTest {
    //[...]
}

nats:
  server:
    hb_fail_count: 3

nats.server.hb_fail_count=3

Java Nats Streaming Spring Example

Deprecation Notice

• Supports spring config
• Configuration Properties are overwriting the spring properties

@SpringBootTest
@RunWith(SpringRunner.class)
@EnableNatsStreamingServer(port = 4222, config = {"user", "admin", "pass", "admin"})
public class SomeTest {
    //[...]
}

nats:
  streaming:
    server:
      hb_fail_count: 3

nats.streaming.server.hb_fail_count=3