1.1.4. ROS 1 - ROS 2 bridge¶

Another typical situation of systems using different protocols is that of ROS 1 and ROS 2.

By using Integration Service, this communication can be achieved with minimum user’s effort. As both a ROS 1 System Handle and a ROS 2 System Handle already exist, the communication is straightforward.

In the example below, we show how Integration Service puts into communication two pub-echo examples, one from ROS 2, and the other from ROS 1.

1.1.4.1. Requirements¶

To prepare the deployment and setup the environment, you need to have Integration Service correctly installed in your system. To do so, please follow the steps delineated in the Installation section.

Also, to get this example working, the following requirements must be met:

Having ROS 2 (Foxy or superior) installed, with the talker-listener example working.
Having the ROS 2 System Handle installed. You can download it from the ROS2-SH dedicated repository into the is-workspace where you have Integration Service installed:
```
cd ~/is-workspace
git clone https://github.com/eProsima/ROS2-SH.git src/ROS2-SH
```
Having ROS 1 (Melodic or superior) installed, with the pub-echo example working.
Having the ROS 1 System Handle installed. You can download it from the ROS1-SH dedicated repository into the is-workspace where you have Integration Service installed:
```
cd ~/dds-is-workspace
git clone https://github.com/eProsima/ROS1-SH.git src/ROS1-SH
```

After you have everything correctly installed, build the packages by running:

source /opt/ros/$<ROS2_DISTRO>/setup.bash
colcon build --packages-skip-regex is-ros1
source /opt/ros/$<ROS1_DISTRO>/setup.bash
colcon build

1.1.4.2. Deployment¶

Below we explain how to deploy an example of this communication in both directions allowed.

ROS 1 pub to ROS 2 echo¶

To enable communication from ROS 1 to ROS 2, open four terminals:

In the first terminal, source the ROS 1 installation and run the roscore:
```
source /opt/ros/$<ROS1_DISTRO>/setup.bash
roscore
```

In the second terminal, source the ROS 1 installation and launch the ROS 1 pub:

source /opt/ros/$<ROS1_DISTRO>/setup.bash
rostopic pub -r 1 /hello_ros2 std_msgs/String "Hello, ros2"

In the third terminal, source the ROS 2 installation and launch the ROS 2 echo:

source /opt/ros/$<ROS2_DISTRO>/setup.bash
ros2 topic echo /hello_ros2 std_msgs/String

In the fourth terminal, go to the is-workspace folder, source the ROS 2, the ROS 1, and local installations, and execute Integration Service with the integration-service command followed by the ros1_ros2__helloworld.yaml configuration file located in the src/Integration-Service/examples/basic folder:
```
cd ~/is-workspace
source /opt/ros/$<ROS2_DISTRO>/setup.bash
source /opt/ros/$<ROS1_DISTRO>/setup.bash
source install/setup.bash
integration-service src/Integration-Service/examples/basic/ros1_ros2__helloworld.yaml
```

Once Integration Service is launched, the ROS 1 pub and the ROS 2 echo will start communicating.

ROS 2 pub to ROS 1 echo¶

To enable communication from ROS 2 to ROS 1, open four terminals:

In the first terminal, source the ROS 1 installation and run the roscore:
```
source /opt/ros/$<ROS1_DISTRO>/setup.bash
roscore
```

In the second terminal, source the ROS 2 installation and launch the ROS 2 pub:

source /opt/ros/$<ROS2_DISTRO>/setup.bash
ros2 topic pub -r 1 /hello_ros1 std_msgs/String "{data: \"Hello, ros1\"}"

In the third terminal, source the ROS 1 installation and launch the ROS 1 echo:
```
source /opt/ros/$<ROS1_DISTRO>/setup.bash
rostopic echo /hello_ros1
```
In the fourth terminal, go to the is-workspace folder, source the ROS 2, the ROS 1, and local installations, and execute Integration Service with the integration-service command followed by the ros1_ros2__helloworld.yaml configuration file located in the src/Integration-Service/examples/basic folder:
```
cd ~/is-workspace
source /opt/ros/$<ROS1_DISTRO>/setup.bash
source /opt/ros/$<ROS2_DISTRO>/setup.bash
source install/setup.bash
integration-service src/Integration-Service/examples/basic/ros1_ros2__helloworld.yaml
```

Once Integration Service is launched, the ROS 2 pub and the ROS 1 echo will start communicating.