The package assumes a ROS2 installation
that supports pyproject.toml files to specify the build system requirements
and Poetry. The package can be placed in the src
directory of a valid ROS2 workspace and built with
colcon just like any
other package.
The package can be installed with colcon using
colcon-poetry-ros to provide
Poetry support to colcon, from the workspace folder:
colcon build --packages-select fastapi_ros2
Once the overlay has been sourced, the package can be used as a normal ROS2 package,
with the caveat that the scripts are not enabled for the ros2 run command.
They can however be run with Python directly from the workspace's install folder.
For the simple publisher node:
python3 install/fastapi_ros2/lib/fastapi_ros2/print_publisher
For the service nodes (in different terminals):
python3 install/fastapi_ros2/lib/fastapi_ros2/service
python3 install/fastapi_ros2/lib/fastapi_ros2/add_server
poetry run python -m fastapi_ros2.examples.print_publisher
The current version of the API has the following endpoints available:
These allow:
- publishing to a topic
/printa message of typestring, using thetopicsroute. - place a request to the service
example_interfaces.srv.AddTwoIntsto sum up two integers and get the result back. - place a request to the service
turtlesim.srv.TeleportAbsoluteto perform an absolute movement (position in cartesian x,y coordinates and angle in radians).
To start the app, run the following command from the package root directory:
poetry run uvicorn main:app
Then go to http://127.0.0.1:8001/docs
This version of the app includes two services endpoints: GET /services/sum and GET /services/move_turtle. The endpoints rely on asynchronous clients for each of the ROS2 services, which poll the status of the service during the spin up, and the API does not start until the services are available (as shown in the previous image).
The services live in the services module of the package, where any new service must be placed. When creating a new service, including both the server and client modules is recommended.
From the package location, start the add_two_ints service:
poetry run python3 /workspace_dir/install/fastapi_ros2/lib/fastapi_ros2/service
NOTE: This command can only be run after installing the packages in the ROS2 workspace, so that the scripts become available (ros2 run equivalent).
From the package location, start the turtlesim service:
ros2 run turtlesim turtlesim_node
This will spawn a new turtlesim window that is tied to the server that will receive the movement requests:
This window will show the movements of the turtle when the GET /services/move_turtle endpoint is used.
When using the endpoint GET /topics/print, from a different terminal, sniff the /print topic with:
ros2 topic echo /print
The terminal should show the messages published to the topic:
The same will apply for any topic added to the API through the topics route.