Ianvs

Ianvs (Janus) is a ROS2 c++ package that provides a transition path for common ROS1 design patterns that aren't as easily supported in ROS2.

This includes:

• A NodeHandle class that works with any ROS2 NodeBase implementation and provides namespaced access to underlying node
• Utility functions for handling getting single messages
• Specialized image publishers and subscribers that work with message filters

Ianvs is intended to only depend on a very select number of core ROS2 dependencies. These are currently:

• message_filters
• rclcpp
• std_srvs
• sensor_msgs

Launch File Extensions

Ianvs includes a custom launch file extension for node that allows the use of specific virtual environments for a node besides the system environment (or the environment the node is built with). This works with --symlink-install.

The underlying mechanism for this is to use the interpreter for the virtual environment for the node launch prefix, which is appended to the launch prefix of the node if it's already specified, or becomes the launch prefix of the node otherwise. You can manually replicate the same behavior if you so choose. This method will not work (at the moment) for child processes (because the child process will use the python interpreter specified by PATH which is not overridden).

You can enable this via:

launch:
  # other launch file contents
  - pyenv_node:
      pkg: some_package
      exec: some_python_node
      name: some_node_name
      pyenv: /path/to/python/environment
      # whatever else you want

This will fail for non-python executables.

Utilities

Ianvs includes an utility for playing a rosbag after modifying the static transforms. The general usage is below:

ros2 run ianvs /path/to/bag [-p prefix] [-s expr:sub]... [-f filter]... [-- ros2 bag play args]

The -- separator is optional in general, but necessary to deconflict with the --start-paused or --storage flags for the ros2 bag play command.

About the Name

Ianvs is the latin spelling of Janus, the Roman deity of doorways and transitions