5.3. Enabling Connext 7.5.0 or Later with any ROS RMW

It is easy to enable compatibility with standalone Connext 7.5.0 or later applications, even with non-Connext RMWs. This approach requires no changes to existing applications, and is configurable through simple XML changes.

Note

These instructions are for using standalone Connext applications with ROS 2 applications, regardless of the RMW used. This approach is ideal if you have an existing ROS 2 system that you cannot change, but you want to utilize the many features of Connext in additional applications.

Ensure these prerequisites:

ROS 2 Kilted

It is recommended to use Ubuntu 24.04 (LTS) and Debian packages for installation, since this platform is referenced throughout the examples. Substitute your platform for x64Linux4gcc7.3.0 throughout the examples if you are using another architecture.
Existing ROS 2 application

The examples throughout this document are based on the Writing a simple publisher and subscriber (C++) and Creating custom msg and serv files (using the cpp_pubsub package with the generated Num type) ROS 2 tutorials. If you have your own existing application, you should substitute your own types and topic names throughout the examples.
Connext 7.5.0 or later

Only your standalone Connext applications must use Connext 7.5.0 or later. That is, your ROS 2 application does not need to use the Connext RMW at all or, if it does, the Connext RMW can be any version, but your standalone Connext application interoperating with your ROS 2 application must be 7.5.0 or later.

You can purchase Connext 7.5.0 (email sales@rti.com for more information) or download a free version.

5.3.1. Publisher/Subscriber Tutorial for Connext 7.5.0+ with any ROS RMW

Create a new directory (outside of your ROS 2 workspace) called connext_ws.

Navigate into the directory and copy the IDL file for your ROS 2 type into the newly created directory:

mkdir ~/connext_ws
cd ~/connext_ws
cp <ros2_ws>/install/tutorial_interfaces/share/tutorial_interfaces/msg/Num.idl .

Configure your Connext environment (note: it is recommended to do this in a separate terminal from the one where you have configured your ROS 2 environment):
```
source <rti_connext_install_directory>/resource/scripts/rtisetenv_x64Linux4gcc7.3.0.bash
```

Generate your Connext example application:

rtiddsgen -example x64Linux4gcc7.3.0 -language c++11 Num.idl

Edit Num_publisher.cxx and Num_subscriber.cxx to set the topic name to topic:

dds::topic::Topic< ::tutorial_interfaces::msg::Num> topic(participant, "topic");

Compile your Connext application:
```
make -f makefile_x64Linux4gcc7.3.0
```
In one terminal, run the Connext subscriber:
```
./objs/x64Linux4gcc7.3.0/Num_subscriber
```
In another terminal, run the ROS 2 publisher:
```
ros2 run cpp_pubsub talker
```

Verify the Connext subscriber does not receive data from the ROS 2 publisher:

::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...

Terminate both applications with Ctrl-C.
In one terminal, run the Connext publisher:
```
./objs/x64Linux4gcc7.3.0/Num_publihser
```
In another terminal, run the ROS 2 subscriber:
```
ros2 run cpp_pubsub listener
```
Verify the ROS 2 subscriber does not receive data from the Connext publisher (there will be no output).
Terminate both applications with Ctrl-C.

Open USER_QOS_PROFILES.xml and add the following to the <domain_participant_qos> tag:

<property>
        <value>
                <element>
                        <name>dds.ros.enable_interoperability</name>
                        <value>TRUE</value>
                </element>
        </value>
</property>

Relaunch the Connext subscriber application:
```
./objs/x64Linux4gcc7.3.0/Num_subscriber
```
Relaunch the ROS 2 publisher application:
```
ros2 run cpp_pubsub talker
```

Verify that the Connext subscriber application now starts receiving data from the ROS 2 publisher application:

::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
[num: 0]
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
[num: 1]
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
[num: 2]
::tutorial_interfaces::msg::Num subscriber sleeping up to 1 sec...
[num: 3]

Terminate the applications.
In one terminal, run the Connext publisher:
```
./objs/x64Linux4gcc7.3.0/Num_publisher
```
In another terminal, run the ROS 2 subscriber:
```
ros2 run cpp_pubsub listener
```

Verify the ROS 2 subscriber receives data:

[INFO] [1738350344.675343878] [minimal_subscriber]: I heard: '1'
[INFO] [1738350345.672977712] [minimal_subscriber]: I heard: '2'

Terminate both applications with Ctrl-C.

5.3.2. Service/Client Tutorial for Connext 7.5.0+ with any ROS RMW

Create a new directory (outside of your ROS 2 workspace) called connext_ws.

Copy the request/reply example from the RTI workspace into your new directory:

mkdir ~/connext_ws
cd ~/connext_ws
cp -r <path to RTI workspace>/7.5.0/examples/connext_dds/c++11/hello_world_request_reply .

Copy the ROS 2 IDL into the source directory in the copied example:

cp <ros2_ws>//install/tutorial_interfaces/share/tutorial_interfaces/srv/AddThreeInts.idl hello_world_request_reply/src/

Configure your Connext environment (note: it is recommended to do this in a separate terminal from the one where you have configured your ROS 2 environment):
```
source <rti_connext_install_directory>/resource/scripts/rtisetenv_x64Linux4gcc7.3.0.bash
```

Navigate into hello_world_request_reply/src and generate new type files using AddThreeInts.idl:

cd hello_world_request_reply/src
rtiddsgen -create typefiles -platform x64Linux4gcc7.3.0 -language c++11 AddThreeInts.idl

Make a copy of PrimeNumberRequester.cxx named AddThreeIntsRequester.cxx and a copy of PrimeNumberReplier.cxx named AddThreeIntsReplier.cxx:
```
cp PrimeNumberRequester.cxx AddThreeIntsRequester.cxx
cp PrimeNumberReplier.cxx AddThreeIntsReplier.cxx
```

Open AddThreeIntsRequester.cxx and make the following changes to use the AddThreeInts type instead of the Prime type:

Note

require_matching_service_on_send_request must be set to false in the RequesterParams, and requester.wait_for_service cannot be used when seeking interoperability with other DDS vendors.

/****************************************************************************/
/* (c) Copyright, Real-Time Innovations, All rights reserved.          */
/* */
/* Permission to modify and use for internal purposes granted.      */
/* This software is provided "as is", without warranty, express or implied. */
/* */
/****************************************************************************/

#include "AddThreeInts.hpp"  // generated support for the request and reply types
#include <rti/request/rtirequest.hpp>  // full request-reply API
#include <rti/util/util.hpp>        // for sleep()
#include <rti/config/Logger.hpp>     // Logger to configure logging verbosity

class AddThreeIntsRequesterExample {
private:
        dds::domain::DomainParticipant participant;

public:
        explicit AddThreeIntsRequesterExample(int domain_id) : participant(
                domain_id,
                dds::core::QosProvider::Default().participant_qos("RequestReplyExampleProfiles::ParticipantExampleProfile"))
        { }

        void run_example(int x, int y, int z)
        {
                const auto max_wait = dds::core::Duration::from_secs(20);

                // Create the Requester with the participant, a service name (which has
                // be the same as the one used in the Replier) and optionally a QoS
                // profile (defined in USER_QOS_PROFILES.xml).
                rti::request::RequesterParams requester_params(participant);
                auto qos_provider = dds::core::QosProvider::Default();
                requester_params.service_name("add_three_ints");
                requester_params.require_matching_service_on_send_request(false);

                rti::request::Requester<tutorial_interfaces::srv::AddThreeInts_Request, tutorial_interfaces::srv::AddThreeInts_Response> requester(
                        requester_params);

                // Wait for a service to be available
                sleep(2);

                // Send the request
                auto request_id =
                        requester.send_request(tutorial_interfaces::srv::AddThreeInts_Request(x, y, z));

                // Receive replies
                bool in_progress = true;
                while (in_progress) {
                        auto replies = requester.receive_replies(max_wait);

                        // When receive_replies times out,
                        // it returns an empty reply collection
                        if (replies.length() == 0) {
                                throw std::runtime_error("Timed out waiting for replies");
                                return;
                        }

                        // Print the prime numbers we receive
                        for (const auto& reply : replies) {
                                if (!reply.info().valid()) {
                                        continue;
                                }

                                std:: cout << "Received sum " << reply.data().sum() << std::endl;
                                }
                }
        }
};

int requester_main(int x, int y, int z, int domain_id)
{
        std::cout << "AddThreeIntsRequester: Sending a request to calculate the "
                        << "sum of " << x << ", " << y << ", " << z << std::endl;

        try {
                AddThreeIntsRequesterExample(domain_id).run_example(x, y, z);
        } catch (const std::exception& ex) {
                std::cout << "Exception: " << ex.what() << std::endl;
                return -1;
        }

        return 0;
}

#if !(defined(RTI_VXWORKS) && !defined(__RTP__)) && !defined(RTI_PSOS)
int main(int argc, char *argv[])
{
        int domain_id = 0;
        int x, y, z;

        if (argc < 4) {
                std::cout << "AddThreeIntsRequester" << std::endl
                                << "Sends a request to calculate the sum"
                                << std::endl
                                << "Parameters: <x> <y> <z> [<domain_id>=0]"
                                << std::endl;
                return -1;
        }

        x = atoi(argv[1]);
        y = atoi(argv[2]);
        z = atoi(argv[3]);

        if (argc > 4) {
                domain_id = atoi(argv[4]);
        }

        return requester_main(x, y, z, domain_id);
}
#endif

Open AddThreeIntsReplier.cxx and make the following changes to use the AddThreeInts type instead of the Prime type:

/****************************************************************************/
/* (c) Copyright, Real-Time Innovations, All rights reserved.          */
/* */
/* Permission to modify and use for internal purposes granted.      */
/* This software is provided "as is", without warranty, express or implied. */
/* */
/****************************************************************************/

#include "AddThreeInts.hpp"  // generated support for the request and reply types
#include <rti/request/rtirequest.hpp>  // full request-reply API
#include <rti/config/Logger.hpp>     // Logger to configure logging verbosity
#include <cmath>

class AddThreeIntsReplierExample {
private:
        dds::domain::DomainParticipant participant;

public:
        explicit AddThreeIntsReplierExample(int domain_id) : participant(
                domain_id,
                dds::core::QosProvider::Default().participant_qos("RequestReplyExampleProfiles::ParticipantExampleProfile"))
        { }

private:
        void calculate_and_send_sum(
                rti::request::Replier<tutorial_interfaces::srv::AddThreeInts_Request, tutorial_interfaces::srv::AddThreeInts_Response> replier,
                const rti::sub::LoanedSample<tutorial_interfaces::srv::AddThreeInts_Request>& request)
        {
                int64_t a =
                        static_cast<int64_t>(request.data().a());
                int64_t b =
                        static_cast<int64_t>(request.data().b());
                int64_t c =
                        static_cast<int64_t>(request.data().c());

                tutorial_interfaces::srv::AddThreeInts_Response reply;
                reply.sum() = a + b + c;;

                    replier.send_reply(reply, request.info());
                    }

public:
    void run_example()
    {
        // Create the Replier with the participant, a service name and
        // optionally a QoS profile (defined in USER_QOS_PROFILES.xml).
        auto qos_provider = dds::core::QosProvider::Default();
        rti::request::ReplierParams replier_params(participant);
        replier_params.service_name("add_three_ints");

        rti::request::Replier<tutorial_interfaces::srv::AddThreeInts_Request, tutorial_interfaces::srv::AddThreeInts_Response> replier(
                replier_params);

        // Receive requests and process them
        const auto MAX_WAIT = dds::core::Duration::from_secs(20);
        auto requests = replier.receive_requests(MAX_WAIT);
        while (requests.length() > 0) {  // end the requester when no requests
                                        // received in MAX_WAIT
            for (const auto& request : requests) {
                if (!request.info().valid()) {
                    continue;
                }

                std::cout << "Calculating sum of " <<
                        request.data().a() << ", " <<
                        request.data().b() << ", " <<
                        request.data().c() << std::endl;


                calculate_and_send_sum(replier, request);

                std::cout << "Sent reply" << std::endl;
            }

              requests = replier.receive_requests(MAX_WAIT);
        }
    }
};

int replier_main(int domain_id)
{
        rti::config::Logger::instance().verbosity(
                rti::config::Verbosity::WARNING);


    std::cout << "AddThreeIntsReplier running (on domain " << domain_id << ")"
            << std::endl;

    try {
        AddThreeIntsReplierExample(domain_id).run_example();
    } catch (const std::exception& ex) {
        std::cout << "Exception: " << ex.what() << std::endl;
        return -1;
    }

    return 0;
}

#if !(defined(RTI_VXWORKS) && !defined(__RTP__)) && !defined(RTI_PSOS)
int main(int argc, char *argv[])
{
    int domain_id = 0;

    if (argc > 1) {
        domain_id = atoi(argv[1]);
    }
    return replier_main(domain_id);
}
#endif

Modify USER_QOS_PROFILES.xml to include a DomainParticipant QoS profile and remove the existing snippets that set the Durability on the reader and writer (otherwise the endpoints may be incompatible with the ROS 2 endpoints):

<?xml version="1.0"?>

<dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="http://community.rti.com/schema/7.5.0/rti_dds_qos_profiles.xsd">

        <qos_library name="RequestReplyExampleProfiles">

                <qos_profile name="RequesterExampleProfile"
                                base_name="BuiltinQosLib::Pattern.RPC">
                </qos_profile>

                <qos_profile name="ReplierExampleProfile"
                                base_name="BuiltinQosLib::Pattern.RPC">
                </qos_profile>

                <qos_profile name="ParticipantExampleProfile"
                                base_name="BuiltinQosLib::Pattern.RPC">
                </qos_profile>
        </qos_library>
</dds>

Modify make/makefile_RequestReplyPrimes_x64Linux4gcc7.3.0 to compile AddThreeInts code:

######################################################################
# makefile_Primes_x64Linux4gcc7.3.0#
# (c) Copyright, Real-Time Innovations, 2012.  All rights reserved.
# RTI grants Licensee a license to use, modify, compile, and create
# derivative works of the software solely for use with RTI Connext DDS.
# Licensee may redistribute copies of the software provided that all such
# copies are subject to this license. The software is provided "as is",
# with no warranty of any type, including any warranty for fitness for
# any purpose. RTI is under no obligation to maintain or support the
# software. RTI shall not be liable for any incidental or consequential
# damages arising out of the use or inability to use the software.
#
#
# This makefile was automatically generated by RTI Code Generator (rtiddsgen)
# version 4.5.0.
#
#
# Note: This makefile is only meant to build our example applications and
#       may require alterations to build on your system.
#
# This makefile assumes that your build environment is already correctly
# configured. (For example, the correct version of your compiler and
# linker should be in your PATH.)
######################################################################


SOURCE_DIR = src/

TARGET_ARCH = x64Linux4gcc7.3.0

#TOOLSROOT = # Set the location of the toolchain
#COMPILERSYSROOT = $(TOOLSROOT)/build/tmp/sysroots/genericx86-64
#COMPILER_PATH = $(TOOLSROOT)/build/tmp/sysroots/x86_64-linux/usr/bin/x86_64-wrs-linux


ifndef COMPILER
        COMPILER = <span class="math-inline">\(COMPILER\_PATH\)</span>(GCC_PREFIX)g++
endif
COMPILER_FLAGS = -m64 -Wall $(ADDITIONAL_COMPILER_FLAGS) -std=c++14
ifndef LINKER
        LINKER = <span class="math-inline">\(COMPILER\_PATH\)</span>(GCC_PREFIX)g++
endif
LINKER_FLAGS = -m64 <span class="math-inline">\(ADDITIONAL\_LINKER\_FLAGS\)
SYSLIBS \= \-ldl \-lm \-lpthread \-lrt \-no\-pie \-rdynamic
DEFINES \= \-DRTI\_UNIX \-DRTI\_LINUX \-DRTI\_64BIT
ifndef DEBUG
DEBUG\=0
endif
ifeq \(</span>(DEBUG),1)
            COMPILER_FLAGS += -g -O0
            LINKER_FLAGS += -g
            DEBUG_SFX = d
    else
            DEBUG_SFX =
    endif

    ifndef SHAREDLIB
            SHAREDLIB=0
    endif


    ifeq (<span class="math-inline">\(SHAREDLIB\),1\)
SHAREDLIB\_SFX \=
STATIC\_LIBRARIES \=
else
SHAREDLIB\_SFX \= z
DEFINES \+\= \-DRTI\_STATIC
endif
INCLUDES \= \-I\. \-I</span>(NDDSHOME)/include -I$(NDDSHOME)/include/ndds -I$(NDDSHOME)/include/ndds/hpp

    LIBS = -L$(NDDSHOME)/lib/<span class="math-inline">\(TARGET\_ARCH\)
LIBS \+\= \-lrticonnextmsgcpp2</span>(SHAREDLIB_SFX)<span class="math-inline">\(DEBUG\_SFX\)
LIBS \+\=  \-lnddscpp2</span>(SHAREDLIB_SFX)<span class="math-inline">\(DEBUG\_SFX\) \-lnddsc</span>(SHAREDLIB_SFX)<span class="math-inline">\(DEBUG\_SFX\) \-lnddscore</span>(SHAREDLIB_SFX)$(DEBUG_SFX)

    $(STATIC_LIBRARIES) $(SYSLIBS)

    CDRSOURCES      = AddThreeInts.idl
    SOURCES = $(SOURCE_DIR)AddThreeIntsPlugin.cxx $(SOURCE_DIR)AddThreeInts.cxx
    COMMONSOURCES = $(notdir <span class="math-inline">\(SOURCES\)\)
EXEC            \= AddThreeIntsRequester AddThreeIntsReplier
DIRECTORIES     \= objs\.dir objs/</span>(TARGET_ARCH).dir
    COMMONOBJS      = <span class="math-inline">\(COMMONSOURCES\:%\.cxx\=objs/</span>(TARGET_ARCH)/%.o)

    # We actually stick the objects in a sub directory to keep your directory clean.
    $(TARGET_ARCH) : $(DIRECTORIES) $(COMMONOBJS)
            <span class="math-inline">\(EXEC\:%\=objs/</span>(TARGET_ARCH)/%.o)
            <span class="math-inline">\(EXEC\:%\=objs/</span>(TARGET_ARCH)/%)

    objs/<span class="math-inline">\(TARGET\_ARCH\)/% \: objs/</span>(TARGET_ARCH)/%.o
            $(LINKER) $(LINKER_FLAGS) -o $@ $@.o $(COMMONOBJS) <span class="math-inline">\(LIBS\)
objs/</span>(TARGET_ARCH)/%.o : $(SOURCE_DIR)%.cxx  $(SOURCE_DIR)AddThreeInts.hpp
            $(COMPILER) $(COMPILER_FLAGS) -o $@ $(DEFINES) $(INCLUDES) -c $<

    #
    # Uncomment these lines if you want the support files regenerated when idl
    # file is modified
    #
    #
    #  $(SOURCE_DIR)PrimesPlugin.cxx $(SOURCE_DIR)Primes.cxx \
    #  $(SOURCE_DIR)Primes.hpp $(SOURCE_DIR)PrimesPlugin.hpp $(SOURCE_DIR)application.hpp : \
    #       $(SOURCE_DIR)Primes.idl
    #   $(NDDSHOME)/bin/rtiddsgen $(SOURCE_DIR)Primes.idl -replace -language C++11
    #
    # Here is how we create those subdirectories automatically.
    %.dir :
            @echo "Checking directory $*"
            @if [ ! -d $* ]; then \
                    echo "Making directory $*"; \
                    mkdir -p $* ; \
            fi;

Compile the AddThreeInts Requester and Replier:

make -f make/makefile_RequestReplyPrimes_x64Linux4gcc7.3.0

Launch the Connext AddThreeInts Replier:

./objs/x64Linux4gcc7.3.0/AddThreeIntsReplier

Launch the ROS 2 client:
```
ros2 run cpp_srvcli client 1 2 3
```

Verify the Connext application does not receive the request and the ROS 2 client does not receive a reply.

Connext output:

AddThreeIntsReplier running (on domain 0)

ROS 2 output:

[INFO] [time] [rclcpp]: service not available, waiting again...
[INFO] [time] [rclcpp]: service not available, waiting again...
[INFO] [time] [rclcpp]: service not available, waiting again...
[INFO] [time] [rclcpp]: service not available, waiting again...

Terminate the applications. Launch the Connext AddThreeInts Requester:
```
./objs/x64Linux4gcc7.3.0/AddThreeIntsRequester 1 2 3
```
Launch the ROS 2 server:
```
ros2 run cpp_srvcli server
```
Verify the ROS 2 server does not receive a request and the Connext application does not receive a reply.

ROS 2 output:
```
[INFO] [time] [rclcpp]: Ready to add three ints
```
Connext output:
```
AddThreeIntsRequester: Sending a request to calculate the sum of 1, 2, 3
```

Enable ROS 2 interoperability by setting dds.ros.enable_interoperability in USER_QOS_PROFILES.xml:

<?xml version="1.0"?>

<dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="http://community.rti.com/schema/7.5.0/rti_dds_qos_profiles.xsd">

    <qos_library name="RequestReplyExampleProfiles">

        <!-- Use these profiles to customize the Requester or Replier QoS -->

        <!-- These profiles inherit from the built-in profile
            BuiltinQosLib::Pattern.RPC, which defines the default values for
            the DataWriters and DataReaders created by a Requester or Replier
        -->
        <qos_profile name="RequesterExampleProfile"
                    base_name="BuiltinQosLib::Pattern.RPC">
        </qos_profile>

        <qos_profile name="ReplierExampleProfile"
                    base_name="BuiltinQosLib::Pattern.RPC">
        </qos_profile>

        <qos_profile name="ParticipantExampleProfile"
                    base_name="BuiltinQosLib::Pattern.RPC">
            <domain_participant_qos>
                <property>
                    <value>
                        <element>
                            <name>dds.ros.enable_interoperability</name>
                            <value>TRUE</value>
                        </element>
                    </value>
                </property>
            </domain_participant_qos>
        </qos_profile>
    </qos_library>
</dds>

Launch the Connext AddThreeInts Replier:

./objs/x64Linux4gcc7.3.0/AddThreeIntsReplier

Launch the ROS 2 client:
```
ros2 run cpp_srvcli client 1 2 3
```

Verify the request is received and processed:

Connext output:

AddThreeIntsReplier running (on domain 0)
Calculating sum of 1, 2, 3
Sent reply

ROS 2 output:

[INFO] [time] [rclcpp]: Sum: 43

Terminate the applications. Launch the Connext AddThreeInts Requester:
```
./objs/x64Linux4gcc7.3.0/AddThreeIntsRequester
```
Launch the ROS 2 server:
```
ros2 run cpp_srvcli server
```

Verify the request is received and processed:

ROS 2 output:

[INFO] [time] [rclcpp]: Ready to add three ints
[INFO] [time] [rclcpp]: Incoming request
a: 1 b: 2 c: 3
[INFO] [time] [rclcpp]: sending back response: [6]

Connext output:

AddThreeIntsRequester: Sending a request to calculate the sum of 1, 2, 3
Received sum 6