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FastDDS Interoperability

HDDS is certified compatible with eProsima FastDDS 2.x.

Requirements​

  • FastDDS 2.10+ (recommended 2.14+)
  • Same domain ID on both ends
  • Compatible QoS policies

Quick Test​

HDDS Publisher​

use hdds::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let participant = DomainParticipant::new(0)?;
    let topic = participant.create_topic::<HelloWorld>("HelloWorldTopic")?;
    let publisher = participant.create_publisher()?;
    let writer = publisher.create_writer(&topic)?;

    loop {
        writer.write(&HelloWorld {
            message: "Hello from HDDS!".to_string(),
        })?;
        std::thread::sleep(std::time::Duration::from_secs(1));
    }
}

FastDDS Subscriber (C++)​

#include <fastdds/dds/domain/DomainParticipantFactory.hpp>
#include <fastdds/dds/subscriber/Subscriber.hpp>
#include <fastdds/dds/subscriber/DataReader.hpp>

int main() {
    auto factory = DomainParticipantFactory::get_instance();
    auto participant = factory->create_participant(0, PARTICIPANT_QOS_DEFAULT);

    // Register type
    TypeSupport type(new HelloWorldPubSubType());
    type.register_type(participant);

    auto topic = participant->create_topic("HelloWorldTopic", "HelloWorld", TOPIC_QOS_DEFAULT);
    auto subscriber = participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
    auto reader = subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);

    // Read loop
    HelloWorld sample;
    SampleInfo info;
    while (true) {
        if (reader->take_next_sample(&sample, &info) == ReturnCode_t::RETCODE_OK) {
            std::cout << "Received: " << sample.message() << std::endl;
        }
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
    }
}

IDL Type Definition​

Both sides must use matching types:

// HelloWorld.idl
struct HelloWorld {
    string message;
};

Generate for FastDDS:

fastddsgen HelloWorld.idl

Generate for HDDS:

hdds-gen gen --target rust HelloWorld.idl

QoS Compatibility​

Verified Profiles​

ProfileReliabilityDurabilityHistoryStatus
Sensor StreamingBestEffortVolatileKeepLast(1)✅
State SyncReliableTransientLocalKeepLast(10)✅
Event LogReliableTransientLocalKeepAll✅

FastDDS QoS (XML)​

<?xml version="1.0" encoding="UTF-8"?>
<dds>
    <profiles>
        <data_writer_qos profile_name="hdds_interop">
            <reliability>
                <kind>RELIABLE_RELIABILITY_QOS</kind>
            </reliability>
            <durability>
                <kind>TRANSIENT_LOCAL_DURABILITY_QOS</kind>
            </durability>
            <history>
                <kind>KEEP_LAST_HISTORY_QOS</kind>
                <depth>10</depth>
            </history>
        </data_writer_qos>
    </profiles>
</dds>

HDDS QoS (Rust)​

let qos = DataWriterQos::default()
    .reliability(Reliability::Reliable {
        max_blocking_time: Duration::from_secs(1),
    })
    .durability(Durability::TransientLocal)
    .history(History::KeepLast { depth: 10 });

Encapsulation Format​

FastDDS uses PL_CDR_LE (0x0003) for discovery and DL_CDR2_LE for user data:

PhaseFastDDS FormatHDDS Support
SPDPPL_CDR_LE✅
SEDPPL_CDR_LE✅
User DataDL_CDR2_LE / CDR_LE✅

Network Configuration​

Multicast (Default)​

No configuration needed. Both use standard RTPS multicast:

Multicast: 239.255.0.1:7400 (domain 0)

Unicast Only​

If multicast is disabled:

HDDS:

export HDDS_SPDP_UNICAST_PEERS="192.168.1.100:7400"

FastDDS (XML):

<participant profile_name="unicast_participant">
    <rtps>
        <builtin>
            <initialPeersList>
                <locator>
                    <udpv4>
                        <address>192.168.1.100</address>
                        <port>7400</port>
                    </udpv4>
                </locator>
            </initialPeersList>
        </builtin>
    </rtps>
</participant>

Troubleshooting​

Discovery Fails​

  1. Check domain ID: Must match on both sides
  2. Check firewall: UDP ports 7400-7500 open
  3. Check multicast: ping 239.255.0.1

Type Mismatch​

Ensure IDL matches exactly:

  • Same field names
  • Same field types
  • Same field order

QoS Incompatible​

Most common issues:

  • HDDS BestEffort writer → FastDDS Reliable reader (fails)
  • HDDS Volatile → FastDDS TransientLocal reader (fails)

Performance Notes​

MetricValue
Discovery time< 2 seconds
Message latency< 1 ms (same host)
Throughput100K+ msg/s

Next Steps​