Fast DDS 3.x & Cyclone DDS

[sven1904]

I'm currently testing the communication between Fast DDS and Cyclone DDS.
While doing that, I encountered that Fast DDS 3.x has some issues while Fast DDS 2.x doesn't.
Fast DDS 2.x can publish messages which can be read by Cyclone DDS and vice versa.
On the other side, a Fast DDS 3.x subscriber is not able to read from a Cyclone DDS publisher.
The behavior of a Fast DDS 3.x publisher in combination with a Cyclone DDS subscriber is even more interesting.
The publisher 'detects' that someone actually subscribed to the given topic which is why it starts writing messages, but the subscriber does not recognize them and still waits for messages.

The Fast DDS code is taken from the example generated by fastddsgen with the CMake option.
The Cyclone DDS code is also generated by their idlc tool and the publisher/subscriber code is taken from the website.

This is the used IDL file CiaoMondo.idl (which has been used for code generation):

module CiaoMondo
{
    struct Msg
    {
        @key long userID;
        string message;
    };
};

Since Cyclone DDS publisher and subscriber are not generated by icdl, i'll also put them here:

/*
 * Copyright(c) 2006 to 2020 ZettaScale Technology and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
 * v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */
#include <cstdlib>
#include <iostream>
#include <chrono>
#include <thread>

#include "dds/dds.hpp"

#include "CiaoMondo.hpp"

using namespace org::eclipse::cyclonedds;

int main() {
    try {
        std::cout << "=== [CYCLONE][Publisher] Create writer." << std::endl;

        dds::domain::DomainParticipant participant(domain::default_id());

        dds::topic::Topic<CiaoMondo::Msg> topic(participant, "CiaoMondoTopic");

        dds::pub::Publisher publisher(participant);

        dds::pub::DataWriter<CiaoMondo::Msg> writer(publisher, topic);

        std::cout << "=== [CYCLONE][Publisher] Waiting for subscriber." << std::endl;
        while (writer.publication_matched_status().current_count() == 0) {
            std::this_thread::sleep_for(std::chrono::milliseconds(20));
        }

        CiaoMondo::Msg msg(1, "Ciao Mondo! Io sono 'Cyclone DDS'!");

        std::cout << "=== [CYCLONE][Publisher] Write sample: " << msg << std::endl;
        writer.write(msg);

        std::cout << "=== [CYCLONE][Publisher] Waiting for sample to be accepted." << std::endl;
        while (writer.publication_matched_status().current_count() > 0) {
            std::this_thread::sleep_for(std::chrono::milliseconds(50));
        }
    }
    catch (const dds::core::Exception& e) {
        std::cerr << "=== [CYCLONE][Publisher] Exception: " << e.what() << std::endl;
        return EXIT_FAILURE;
    }

    std::cout << "=== [CYCLONE][Publisher] Done." << std::endl;

    return EXIT_SUCCESS;
}

/*
 * Copyright(c) 2006 to 2021 ZettaScale Technology and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
 * v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */
#include <cstdlib>
#include <iostream>
#include <chrono>
#include <thread>

#include "dds/dds.hpp"

#include "CiaoMondo.hpp"

using namespace org::eclipse::cyclonedds;

int main() {
    try {
        std::cout << "=== [CYCLONE][Subscriber] Create reader." << std::endl;

        dds::domain::DomainParticipant participant(domain::default_id());

        dds::topic::Topic<CiaoMondo::Msg> topic(participant, "CiaoMondoTopic");

        dds::sub::Subscriber subscriber(participant);

        dds::sub::DataReader<CiaoMondo::Msg> reader(subscriber, topic);

        std::cout << "=== [CYCLONE][Subscriber] Wait for message." << std::endl;
        int poll = 5;
        while (poll > 0) {
            dds::sub::LoanedSamples<CiaoMondo::Msg> samples;

            samples = reader.take();

            if (samples.length() > 0) {
                dds::sub::LoanedSamples<CiaoMondo::Msg>::const_iterator sample_iter;
                for (sample_iter = samples.begin();
                     sample_iter < samples.end();
                     ++sample_iter) {
                    const CiaoMondo::Msg& msg = sample_iter->data();
                    const dds::sub::SampleInfo& info = sample_iter->info();

                    if (info.valid()) {
                        std::cout << "=== [CYCLONE][Subscriber] Message received: " << msg << std::endl;

                        poll--;
                    }
                }
            } else {
                std::this_thread::sleep_for(std::chrono::milliseconds(20));
            }
        }
    } catch (const dds::core::Exception& e) {
        std::cerr << "=== [CYCLONE][Subscriber] DDS exception: " << e.what() << std::endl;
        return EXIT_FAILURE;
    } catch (const std::exception& e) {
        std::cerr << "=== [CYCLONE][Subscriber] C++ exception: " << e.what() << std::endl;
        return EXIT_FAILURE;
    }

    std::cout << "=== [CYCLONE][Subscriber] Done." << std::endl;

    return EXIT_SUCCESS;
}

Btw, I also checked different versions of Cyclone DDS which made no difference, neither for Fast DDS 3.x nor 2.x.

[juanlofer-eprosima]

Hi @sven1904 ,

One of the most relevant updates that came with Fast-DDS 3 is a refactored XTypes module that is now compliant with the DDS-XTypes standard. With this change it was also decided to publish type information by default. Currently there seems to be interoperability issues with Cyclone DDS due to this fact, but these would probably be avoided by disabling type propagation. Could you please test that?