[ROS2] Configure TCP communication for cloud endpoint

edit

Hi,

I am trying to configure the default rmw_fastrtps middleware in ROS2 to accept messages from a eProsima FastDDS producer via TCP.

The communication between a local eProsima FastDDS producer and a ROS2 node based on the RTPS (UDP) protocol works fine (tested with osrf/ros2 docker image). The idea behind switching to a TCP based DDS communication is that the ROS2 application should run in a public cloud environment that can accept DDS messages from eProsima FastDDS participants.

I could successfully test the producer to cloud communication with two FastDDS participants (local and cloud) according to the documentation: https://fast-dds.docs.eprosima.com/en...

When trying to modify the rmw_fastrtps middleware for accepting TCP connections (compare https://github.com/ros2/rmw_fastrtps) I get following exception when starting the ROS2 executable:

[XMLPARSER Error] Error adding the transport tcp_transport_1. There is other transport with the same id -> Function insertTransportById
[XMLPARSER Error] Error adding profile 'TCPParticipant' from file 'DEFAULT_FASTRTPS_PROFILES.xml' -> Function extractParticipantProfile
terminate called after throwing an instance of 'eprosima::fastcdr::exception::NotEnoughMemoryException' what():  Not enough memory in the buffer stream

DEFAULT_FASTRTPS_PROFILES.xml

<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com/XMLSchemas/fastRTPS_Profiles">
<transport_descriptors>
    <transport_descriptor>
        <transport_id>tcp_transport_1</transport_id>
        <type>TCPv4</type>
        <sendBufferSize>9216</sendBufferSize>
        <receiveBufferSize>9216</receiveBufferSize>
        <listening_ports>
            <port>7400</port>
        </listening_ports>
        <wan_addr>172.17.0.2</wan_addr>
    </transport_descriptor>
</transport_descriptors>

<participant profile_name="TCPParticipant">
    <rtps>
        <userTransports>
            <transport_id>tcp_transport_1</transport_id>
        </userTransports>
        <useBuiltinTransports>false</useBuiltinTransports>
    </rtps>
</participant>
</profiles>

Changing the ID did not help.

I could not find any examples if a TCP based communication is even possible. Even in the rclpy documentation I couldn’t find any hints that the TCP transport could be configured programmatically.

Is this possible? What other option can be chosen when the ROS2 participant should run in a cloud environment?