NoDL - Node Definition Language

NoDL (Node Definition Language) is a schema and toolkit to describe a ROS 2 node’s interface: parameters, topics (publishers and subscriptions), services (clients and servers), and actions (clients and servers).

Find complete documentation at https://nodl.readthedocs.io/en/latest/

Repository structure

• ament_nodl/: CMake macros to register NoDL documents with the ament index
• nodl/: Metapackage that pulls in the other packages as dependencies. Acts as an easy default for those who don’t want a-la-carte.
  • doc/: Documentation source for the ReadTheDocs page
• nodl_common_interfaces/: NoDL descriptions for standard ROS 2 node base classes (rclcpp::Node, rclcpp_lifecycle::LifecycleNode), registered in the ament index until upstream ships its own.
• nodl_docgen/: Sphinx extension rendering a NoDL document into a documentation page at build time.
• nodl_generator_cpp/: C++ code generator — produces an abstract base class from a NoDL document, with a CMake macro for build integration.
• nodl_observe/: C++ (ament_cmake) package that observes a running ROS 2 node and produces its runtime interface as a rosgraph_msgs/Node message — a reusable observe_node(...) library plus an observe executable. Stage one of Observe → Describe.
• nodl_schema/: Package providing the NoDL schema, plus a Python package with validation tools and typed data model to work with it. nodl.schema.yaml: The NoDL schema, key to this whole thing!
• ros2nodl/: ros2cli extension providing ros2 nodl ... commands
• test_nodl_generator_cpp/: Integration tests for nodl_generator_cpp — exercises the CMake macro end-to-end.
• tools/: Scripts supporting development and build workflows

Developing

Setup

1. Clone the repo and install pre-commit hooks:

pre-commit install
pre-commit install --hook-type prepare-commit-msg

The prepare-commit-msg hook will automatically add the Signed-off-by line to your commits. If you prefer to sign off manually, use git commit -s.

Pip dependencies for full test suite

The packages in this repository use a few package only available from pip as test_depends.

For the buildfarm environment, these dependencies and tests are disabled, because a package may not be packaged into a deb/rpm against dependencies from another package manager (pip).

To install all dependencies and run the full test suite, export environment variable ENABLE_PIP_TEST_DEPENDS=1 - which the GitHub Action CI for this repo does.