This app exemplifies how ROS can be used alongside traditional stacks. This repository wants to explore with a practical approach the paradigms in the middleware ROS (Robotic Operating System) while connecting ROS with external functionalities. Stack used here:
- Catkin package for ROS melodic
- A wrapper class for an SQL database SQLite3
- A JSON parser implemented using a cpp library json
- Interface to a remote API nominatim
A script can render a map with a marker per each city in the database.
The information in the database can be explored with software like sqlite browser obtaining something like:
Note most of the postal entries are zero, this is due to the design of the API which is not returning the postal code. The value can be stored as input in a ros message.
- When launching the main script
roslaunch geo_manager Manager.launch
- A database is created (if doesn't exist) and filled with proper table schema
- A json file is parsed and propagated as an API request. The API response is handled and stored in the db. The user can append cities to the json file, and their information will be processed at startup time.
It will be skipped if the JSON file is not present or empty.
Manager.launchspins the following nodes:
geo_managerapi_handlershow
- The user or a node can request to add a new city to the database via the topic
/RTCreateCitywith:
rostopic pub /RTCreateCity geo_manager/RTCityReq "city_name: 'New York'
postal: 10001"
A unique constraint on the tuple (city - postal) is present. If the tuple (city - postal) is already present in the db, a warning will be returned to the user, otherwise a new row will be placed in the db.
If the API is not able to retrieve the info for a city (i.e. wrong spell of the city or timeout), a warning is returned to the user.
- Visualize in a browser the cities stored in the database with:
rostopic pub /render_cities std_msgs/Empty "{}"
Given your catkin workspace ~/ros_ws, clone the current repository in it with:
cd ~/ros_ws
git clone git@github.com:vignif/ros-example.git src
Check that your system has all the dependencies needed for the project with:
rosdep install --from-paths src --ignore-src -r -y
Build the project with catkin using:
catkin build
Now that everything is built on your machine, you need to source the binaries with:
in case you are using bash
source ~/ros_ws/devel/setup.bash
in case you are using zsh
source ~/ros_ws/devel/setup.zsh
Now you can spin the main nodes with:
roslaunch geo_manager Manager.launch
If you want to change the name of your database you can modify the entry of the Manager.launch file containing the db name.
The schema of the table cities is fixed and is managed with the object Manager.
Run the unit tests using the Catkin Command Line Tools
catkin build db_handler --no-deps --verbose --catkin-make-args run_tests
We use SemVer for versioning. For the versions available, see the tags on this repository.
- Copyright 2021 © Francesco Vigni