FastDDS QoS Mapping

Detailed QoS policy mapping between HDDS and FastDDS (eProsima Fast DDS).

Reliability

HDDS

use hdds::QoS;

// Best Effort
let qos = QoS::best_effort();

// Reliable
let qos = QoS::reliable();

FastDDS (C++ API)

// Best Effort
DataWriterQos wqos;
wqos.reliability().kind = BEST_EFFORT_RELIABILITY_QOS;

// Reliable
DataWriterQos wqos;
wqos.reliability().kind = RELIABLE_RELIABILITY_QOS;
wqos.reliability().max_blocking_time = {0, 100000000}; // 100ms

FastDDS (XML)

<reliability>
    <kind>RELIABLE_RELIABILITY_QOS</kind>
    <max_blocking_time>
        <sec>0</sec>
        <nanosec>100000000</nanosec>
    </max_blocking_time>
</reliability>

Durability

HDDS

use hdds::QoS;

let qos = QoS::reliable().transient_local();

FastDDS (C++ API)

DataWriterQos wqos;
wqos.durability().kind = TRANSIENT_LOCAL_DURABILITY_QOS;

FastDDS (XML)

<durability>
    <kind>TRANSIENT_LOCAL_DURABILITY_QOS</kind>
</durability>

Mapping Table

HDDS	FastDDS C++	FastDDS XML
volatile()	VOLATILE_DURABILITY_QOS	VOLATILE_DURABILITY_QOS
transient_local()	TRANSIENT_LOCAL_DURABILITY_QOS	TRANSIENT_LOCAL_DURABILITY_QOS
persistent()	PERSISTENT_DURABILITY_QOS	PERSISTENT_DURABILITY_QOS

History

HDDS

use hdds::QoS;

// Keep Last
let qos = QoS::reliable().keep_last(10);

// Keep All
let qos = QoS::reliable().keep_all();

FastDDS (C++ API)

// Keep Last
DataWriterQos wqos;
wqos.history().kind = KEEP_LAST_HISTORY_QOS;
wqos.history().depth = 10;

// Keep All
DataWriterQos wqos;
wqos.history().kind = KEEP_ALL_HISTORY_QOS;

FastDDS (XML)

<history>
    <kind>KEEP_LAST_HISTORY_QOS</kind>
    <depth>10</depth>
</history>

Deadline

HDDS

use hdds::QoS;
use std::time::Duration;

let qos = QoS::reliable().deadline(Duration::from_millis(100));

FastDDS (C++ API)

DataWriterQos wqos;
wqos.deadline().period = {0, 100000000}; // 100ms

FastDDS (XML)

<deadline>
    <period>
        <sec>0</sec>
        <nanosec>100000000</nanosec>
    </period>
</deadline>

Liveliness

HDDS

use hdds::QoS;
use std::time::Duration;

let qos = QoS::reliable().liveliness_manual_by_topic(Duration::from_secs(1));

FastDDS (C++ API)

DataWriterQos wqos;
wqos.liveliness().kind = MANUAL_BY_TOPIC_LIVELINESS_QOS;
wqos.liveliness().lease_duration = {1, 0}; // 1 second

FastDDS (XML)

<liveliness>
    <kind>MANUAL_BY_TOPIC_LIVELINESS_QOS</kind>
    <lease_duration>
        <sec>1</sec>
        <nanosec>0</nanosec>
    </lease_duration>
</liveliness>

Mapping Table

HDDS	FastDDS C++	FastDDS XML
liveliness_automatic()	AUTOMATIC_LIVELINESS_QOS	AUTOMATIC_LIVELINESS_QOS
liveliness_manual_by_participant()	MANUAL_BY_PARTICIPANT_LIVELINESS_QOS	MANUAL_BY_PARTICIPANT_LIVELINESS_QOS
liveliness_manual_by_topic()	MANUAL_BY_TOPIC_LIVELINESS_QOS	MANUAL_BY_TOPIC_LIVELINESS_QOS

Complete QoS Example

HDDS Writer QoS

use hdds::{Participant, QoS, TransportMode};
use std::time::Duration;

let participant = Participant::builder("example")
    .domain_id(0)
    .with_transport(TransportMode::UdpMulticast)
    .build()?;

let topic = participant.topic::<SensorData>("SensorTopic")?;

let writer = topic
    .writer()
    .qos(QoS::reliable()
        .keep_last(10)
        .transient_local()
        .deadline(Duration::from_millis(200))
        .liveliness_automatic(Duration::from_secs(5)))
    .build()?;

FastDDS Writer QoS (C++)

DataWriterQos wqos;

// Reliability
wqos.reliability().kind = RELIABLE_RELIABILITY_QOS;
wqos.reliability().max_blocking_time = {0, 100000000};

// Durability
wqos.durability().kind = TRANSIENT_LOCAL_DURABILITY_QOS;

// History
wqos.history().kind = KEEP_LAST_HISTORY_QOS;
wqos.history().depth = 10;

// Deadline
wqos.deadline().period = {0, 200000000};

// Liveliness
wqos.liveliness().kind = AUTOMATIC_LIVELINESS_QOS;
wqos.liveliness().lease_duration = {5, 0};

DataWriter* writer = publisher->create_datawriter(topic, wqos);

FastDDS Writer QoS (XML Profile)

<?xml version="1.0" encoding="UTF-8"?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
    <data_writer profile_name="SensorWriter">
        <qos>
            <reliability>
                <kind>RELIABLE_RELIABILITY_QOS</kind>
                <max_blocking_time>
                    <sec>0</sec>
                    <nanosec>100000000</nanosec>
                </max_blocking_time>
            </reliability>
            <durability>
                <kind>TRANSIENT_LOCAL_DURABILITY_QOS</kind>
            </durability>
            <history>
                <kind>KEEP_LAST_HISTORY_QOS</kind>
                <depth>10</depth>
            </history>
            <deadline>
                <period>
                    <sec>0</sec>
                    <nanosec>200000000</nanosec>
                </period>
            </deadline>
            <liveliness>
                <kind>AUTOMATIC_LIVELINESS_QOS</kind>
                <lease_duration>
                    <sec>5</sec>
                    <nanosec>0</nanosec>
                </lease_duration>
            </liveliness>
        </qos>
    </data_writer>
</profiles>

Duration Format

FastDDS uses a two-part structure for durations:

HDDS	FastDDS
Duration::from_secs(5)	{5, 0} (sec, nanosec)
Duration::from_millis(100)	{0, 100000000}
Duration::from_micros(500)	{0, 500000}
Duration::MAX	{0x7FFFFFFF, 0xFFFFFFFF} (INFINITE)

Compatibility Notes

1. XTypes: FastDDS supports XTypes; use @appendable for type evolution compatibility
2. Transport: Disable FastDDS data sharing for cross-vendor interop
3. Discovery: Both use standard SPDP/SEDP; ports must align

Next Steps

• Setup - Installation and configuration
• Example - Complete interop example
• QoS Translation Matrix - All vendors