JVM (Java) client

The JVM client (implementation("health.varta:varta-client:0.2.0")) is a first-class peer of the Rust varta-client crate. It tracks the same wire-format contract, passes the same tools/vlp-test-vectors.json conformance suite, and interoperates with the same varta-watch observer binary.

Install

// build.gradle.kts
dependencies {
    implementation("health.varta:varta-client:0.2.0")
    // UDS transport requires a SOCK_DGRAM AF_UNIX provider.
    runtimeOnly("com.kohlschutter.junixsocket:junixsocket-core:2.10.1")
}

Targets JDK 17 LTS minimum (Spring Boot 3.x baseline). The base jar has zero runtime dependencies — ChaCha20-Poly1305 comes from standard JCE (Cipher.getInstance("ChaCha20-Poly1305"), JDK 11+), HKDF-SHA256 is implemented in-process via javax.crypto.Mac, CRC-32C uses the hardware-accelerated java.util.zip.CRC32C (JDK 9+).

No shipping JDK exposes SOCK_DGRAM AF_UNIX in standard NIO, so the client probes the classpath at connect() time and uses either junixsocket (recommended) or a future zero-dep FFM module on JDK 22+.

20-line example

import health.varta.*;
import java.nio.file.Path;

try (Varta agent = Varta.connect(Path.of("/run/varta/observer.sock"))) {
    while (true) {
        BeatOutcome outcome = agent.beat(Status.OK, 0);
        if (outcome instanceof BeatOutcome.Dropped d) {
            // Four-way taxonomy mirrors the Rust client:
            DropReason _ = d.reason();
        } else if (outcome instanceof BeatOutcome.Failed f) {
            System.err.println("varta beat failed: " + f.error());
        }
        Thread.sleep(500);
    }
}

For secure UDP, fork-safety, the signal-handler family, and the full parity matrix see the package README in the repo: clients/java/README.md.

Transports

Stability

• Wire format: VLP v0.2, governed by the spec.
• JVM API: independent semver, tracked in clients/java/CHANGELOG.md.

Source

• Maven Central page
• GitHub source
• Issue tracker