holoscan::FastDdsTransport

Beta

DDS-based implementation of PubSubTransport.

Uses FastDDS DataWriter/DataReader for message transport.

#include <holoscan/fastdds_transport.hpp>

Inherits from: nvidia::gxf::PubSubTransport (public)

Constructors

FastDdsTransport

From raw pointer

Copy (deleted)

holoscan::FastDdsTransport::FastDdsTransport(
    FastDdsPubSubContext *context
)

Construct a FastDdsTransport with a FastDdsPubSubContext.

Parameters

context

FastDdsPubSubContext *

FastDdsPubSubContext providing DomainParticipant

Destructor

~FastDdsTransport

holoscan::FastDdsTransport::~FastDdsTransport() override

Destructor - calls shutdown() if needed.

Assignment operators

operator=

FastDdsTransport & holoscan::FastDdsTransport::operator=(
    const FastDdsTransport &
) = delete

Methods

initialize

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::initialize() override

shutdown

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::shutdown() override

is_initialized

bool holoscan::FastDdsTransport::is_initialized() const override

transport_model

nvidia::gxf::TransportModel holoscan::FastDdsTransport::transport_model() const override

DDS is a topic-based transport.

PubSubContext uses this to call send(topic_name, …) once per publish instead of calling send(gid, …) once per subscriber.

native_topic_matching

bool holoscan::FastDdsTransport::native_topic_matching() const override

SEDP handles topic matching + QoS compatibility at the RTPS protocol level.

native_qos_enforcement

bool holoscan::FastDdsTransport::native_qos_enforcement() const override

RTPS-level reliability, durability, and deadline enforcement.

supports_multicast

bool holoscan::FastDdsTransport::supports_multicast() const override

RTPS supports multicast for discovery and data.

requires_explicit_connections

bool holoscan::FastDdsTransport::requires_explicit_connections() const override

DDS DataWriters/DataReaders manage connections internally.

supports_native_buffers

bool holoscan::FastDdsTransport::supports_native_buffers() const override

supports_mixed_local_remote_fanout

bool holoscan::FastDdsTransport::supports_mixed_local_remote_fanout() const override

supports_native_profile

bool holoscan::FastDdsTransport::supports_native_profile(
    const std::string &profile
) const override

send_native_descriptor

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::send_native_descriptor(
    const std::string &topic_name,
    const nvidia::gxf::NativeDescriptorPayload &descriptor,
    const nvidia::gxf::MessageMetadata &metadata
) override

Send a native descriptor on the sidecar topic “{topic}/_native_desc”.

set_native_buffers_enabled

void holoscan::FastDdsTransport::set_native_buffers_enabled(
    bool enabled
)

Enable native buffer support (called by FastDdsPubSubNetworkContext).

connect_to

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::connect_to(
    const nvidia::gxf::EndpointInfo &remote_endpoint
) override

No-op for DDS - discovery is automatic via SPDP/SEDP.

disconnect_from

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::disconnect_from(
    const nvidia::gxf::Gid &remote_gid
) override

No-op for DDS - endpoint lifecycle managed by DDS.

is_connected_to

bool holoscan::FastDdsTransport::is_connected_to(
    const nvidia::gxf::Gid &remote_gid
) const override

Returns true for any endpoint (DDS handles discovery).

create_publisher_endpoint

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::create_publisher_endpoint(
    const std::string &topic_name,
    const nvidia::gxf::Gid &publisher_gid,
    const nvidia::gxf::QoSProfile &qos = nvidia::gxf::QoSProfile{}
) override

Create a DataWriter for a topic.

Called automatically by PubSubContext::register_publisher(). Maps the QoSProfile to FastDDS DataWriterQos via dds_qos::apply_writer_qos().

Returns: Success or error if topic/writer creation fails.

Parameters

topic_name

const std::string &

Name of the topic to publish to.

publisher_gid

const nvidia::gxf::Gid &

GID to associate with this writer.

qos

const nvidia::gxf::QoSProfile &Defaults to nvidia::gxf::QoSProfile{}

QoS profile to apply to the DataWriter.

create_subscriber_endpoint

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::create_subscriber_endpoint(
    const std::string &topic_name,
    const nvidia::gxf::Gid &subscriber_gid,
    const nvidia::gxf::QoSProfile &qos = nvidia::gxf::QoSProfile{}
) override

Create a DataReader for a topic.

Called automatically by PubSubContext::register_subscriber(). Maps the QoSProfile to FastDDS DataReaderQos via dds_qos::apply_reader_qos().

Returns: Success or error if topic/reader creation fails.

Parameters

topic_name

const std::string &

Name of the topic to subscribe to.

subscriber_gid

const nvidia::gxf::Gid &

GID to associate with this reader.

qos

const nvidia::gxf::QoSProfile &Defaults to nvidia::gxf::QoSProfile{}

QoS profile to apply to the DataReader.

remove_publisher_endpoint

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::remove_publisher_endpoint(
    const nvidia::gxf::Gid &publisher_gid
) override

Remove a DataWriter.

Called automatically by PubSubContext::unregister_publisher() and PubSubContext::deinitialize(). For reliable QoS, calls wait_for_acknowledgments() before deletion.

Returns: Success or error if writer not found.

Parameters

publisher_gid

const nvidia::gxf::Gid &

GID of the writer to remove.

remove_subscriber_endpoint

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::remove_subscriber_endpoint(
    const nvidia::gxf::Gid &subscriber_gid
) override

Remove a DataReader.

Called automatically by PubSubContext::unregister_subscriber() and PubSubContext::deinitialize().

Returns: Success or error if reader not found.

Parameters

subscriber_gid

const nvidia::gxf::Gid &

GID of the reader to remove.

send

Overload 1

Overload 2

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::send(
    const nvidia::gxf::Gid &destination_gid,
    const std::vector<uint8_t> &payload,
    const nvidia::gxf::MessageMetadata &metadata
) override

Send payload via DDS DataWriter (GID-based fallback).

This is the GID-based send required by the PubSubTransport interface. For kTopicBased transports, PubSubContext calls the topic-based send() overload instead, so this is a fallback only.

Returns: Success or error if no writer exists for the publisher.

Parameters

destination_gid

const nvidia::gxf::Gid &

IGNORED - DDS publishes to topic, not endpoint.

payload

const std::vector<uint8_t> &

Serialized message (already staged to host memory).

metadata

const nvidia::gxf::MessageMetadata &

Must contain publisher_gid identifying the writer.

set_on_receive

void holoscan::FastDdsTransport::set_on_receive(
    ReceiveCallback callback
) override

set_on_connection_established

void holoscan::FastDdsTransport::set_on_connection_established(
    ConnectionEstablishedCallback callback
) override

set_on_connection_lost

void holoscan::FastDdsTransport::set_on_connection_lost(
    ConnectionLostCallback callback
) override

get_send_queue_size

size_t holoscan::FastDdsTransport::get_send_queue_size() const override

get_receive_queue_size

size_t holoscan::FastDdsTransport::get_receive_queue_size() const override

get_connection_count

size_t holoscan::FastDdsTransport::get_connection_count() const override

get_or_create_topic

eprosima::fastdds::dds::Topic * holoscan::FastDdsTransport::get_or_create_topic(
    const std::string &topic_name
)

Get or create a DDS Topic.

get_or_create_sidecar_writer

eprosima::fastdds::dds::DataWriter * holoscan::FastDdsTransport::get_or_create_sidecar_writer(
    const std::string &topic_name
)

Get or create a sidecar DataWriter for native descriptor messages.

create_sidecar_reader

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::create_sidecar_reader(
    const std::string &topic_name,
    const nvidia::gxf::Gid &subscriber_gid
)

Create a sidecar DataReader for native descriptor messages.

send_impl

nvidia::gxf::Expected<void> holoscan::FastDdsTransport::send_impl(
    const std::string &topic_name,
    const std::vector<uint8_t> &payload,
    const nvidia::gxf::MessageMetadata &metadata
)

Shared send implementation used by both GID-based and topic-based send().

enqueue_sidecar_receive

void holoscan::FastDdsTransport::enqueue_sidecar_receive(
    nvidia::gxf::Gid publisher_gid,
    std::vector<uint8_t> &&payload,
    nvidia::gxf::MessageMetadata metadata
)

Member variables

Name	Type	Description
`context_`	`FastDdsPubSubContext *`
`initialized_`	`bool`
`registered_type_name_`	`std::string`
`type_registered_`	`bool`
`publisher_`	`eprosima::fastdds::dds::Publisher *`
`subscriber_`	`eprosima::fastdds::dds::Subscriber *`
`writers_`	`std::unordered_map< nvidia::gxf::Gid, WriterInfo >`
`readers_`	`std::unordered_map< nvidia::gxf::Gid, ReaderInfo >`
`topics_`	`std::unordered_map< std::string, eprosima::fastdds::dds::Topic * >`
`endpoints_mutex_`	`std::mutex`
`callback_mutex_`	`std::mutex`
`receive_callback_`	`ReceiveCallback`
`connection_established_callback_`	`ConnectionEstablishedCallback`
`connection_lost_callback_`	`ConnectionLostCallback`
`reader_listener_`	`std::unique_ptr< ReaderListener >`
`writer_listener_`	`std::unique_ptr< WriterListener >`
`type_support_`	`eprosima::fastdds::dds::TypeSupport`
`native_buffers_enabled_`	`bool`
`sidecar_writers_`	`std::unordered_map< std::string, SidecarWriterInfo >`
`sidecar_readers_`	`std::unordered_map< std::string, SidecarReaderInfo >`
`sidecar_reader_listener_`	`std::unique_ptr< SidecarReaderListener >`
`sidecar_dispatch_queue_`	`std::unique_ptr< SidecarDispatchQueue >`

Inner classes

WriterInfo

struct holoscan::FastDdsTransport::WriterInfo

Name	Type	Description
`writer`	`eprosima::fastdds::dds::DataWriter *`
`topic`	`eprosima::fastdds::dds::Topic *`
`topic_name`	`std::string`

ReaderInfo

struct holoscan::FastDdsTransport::ReaderInfo

Name	Type	Description
`reader`	`eprosima::fastdds::dds::DataReader *`
`topic`	`eprosima::fastdds::dds::Topic *`
`topic_name`	`std::string`
`subscriber_gid`	`nvidia::gxf::Gid`

SidecarWriterInfo

struct holoscan::FastDdsTransport::SidecarWriterInfo

Name	Type	Description
`writer`	`eprosima::fastdds::dds::DataWriter *`
`topic`	`eprosima::fastdds::dds::Topic *`

SidecarReaderInfo

struct holoscan::FastDdsTransport::SidecarReaderInfo

Name	Type	Description
`reader`	`eprosima::fastdds::dds::DataReader *`
`topic`	`eprosima::fastdds::dds::Topic *`