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Java

ZeroDDS provides a Pure-Java Java-PSM implementation — no JNI, no native library on the Java side. The org.omg.dds.* API (spec-compliant per OMG DDS-Java-PSM 1.0) is delivered as a plain .jar artifact that runs on any JVM. The earlier JNI bridge was retired in favour of pure Java.

Maven

<dependency>
  <groupId>io.zerodds</groupId>
  <artifactId>zerodds-java-omgdds</artifactId>
  <version>${zerodds.version}</version>
</dependency>

Build the artifact locally — its version matches the workspace release:

cd crates/java-omgdds/java
mvn install

What you get

  • org.omg.dds.* — the OMG-defined Java-PSM API surface. Existing application code written against RTI Connext or OpenSplice's Java PSM compiles against this artifact unchanged.
  • org.zerodds.internal.InProcessBus — single-JVM pub/sub loopback.
  • org.zerodds.internal.Xcdr2Codec — Java-native XCDR2 encoder/decoder (per OMG DDS-XTypes 1.3 §7.4).

No libzerodds.so / .dylib / .dll is required on the Java classpath. No System.loadLibrary call. Pure JVM bytecode.

Hello, world

import org.omg.dds.core.*;
import org.omg.dds.domain.*;
import org.omg.dds.pub.*;
import org.omg.dds.topic.*;

public class Hello {
    public static void main(String[] args) throws Exception {
        DomainParticipantFactory factory =
            DomainParticipantFactory.getInstance();
        try (DomainParticipant dp = factory.createParticipant(0)) {
            Topic<Pose> topic = dp.createTopic("Telemetry", Pose.class);
            Publisher pub = dp.createPublisher();
            DataWriter<Pose> writer = pub.createDataWriter(topic);

            writer.write(new Pose("r1", 1.0, 2.0, 3.0));
        }
    }
}

Pose is generated from IDL by zerodds-idlc Robot.idl --java (see crates/idl-java/).

Generated types from IDL

gen/java/com/example/robot/
├── Pose.java                     # POJO with @TopicType
└── Telemetry.java

Each generated class implements org.omg.dds.topic.TopicTypeSupport<T>, carries the @TopicType annotation, and supplies XCDR2 serialise / deserialise methods.

Threading

InProcessBus is thread-safe; multiple Java threads can share one DomainParticipant and publish / subscribe concurrently without app-level locks.

QoS

DataWriterQos qos = DataWriterQos.copyFromTopicQos(topic.getQos());
qos = qos.withPolicy(qos.getReliability().withKind(ReliabilityKind.RELIABLE))
         .withPolicy(qos.getDurability().withKind(DurabilityKind.TRANSIENT_LOCAL));
DataWriter<Pose> w = pub.createDataWriter(topic, qos);

The fluent QoS builder mirrors the OMG DDS Java PSM 1.0 specification.

Listeners

DataReader<Pose> reader = sub.createDataReader(topic);
reader.setListener(new DataReaderListener<Pose>() {
    @Override public void onDataAvailable(DataReader<Pose> r) {
        SampleIterator<Pose> samples = r.take();
        while (samples.hasNext()) {
            Pose p = samples.next().getData();
            System.out.println(p);
        }
    }
});

Spring / Quarkus

Wire DomainParticipant as a bean:

@Configuration
public class DdsConfig {
    @Bean(destroyMethod = "close")
    public DomainParticipant participant() {
        return DomainParticipantFactory.getInstance().createParticipant(0);
    }
}

Multi-process / Cross-vendor

The pure-Java side runs the in-process loopback (InProcessBus). To communicate across JVM processes or with C++ / Rust / C# peers on the RTPS wire, run a bridge daemon and have the Java app speak that protocol — the daemon owns the RTPS stack:

  • gRPC bridge — the Java client talks gRPC to a zerodds-grpc-bridged server.
  • MQTT / AMQP bridge — run zerodds-mqtt-bridged or zerodds-amqp-bridged and publish/subscribe over that protocol.

Reading further

  • crates/java-omgdds/README.md — runtime details.
  • OMG DDS Java PSM 1.0 — formal/2017-04-01.