NoDL - Node Definition Language

NoDL is the Node Definition Language - a common declarative representation of a Node’s interfaces including Parameters, Topics, Services, and Actions. See the design document (review in progress) for more context on the project.

This repository contains the CLI and parsing utilities for NoDL.

Installation

Run python3 setup.py install

Install the ‘ament_nodl’ extension for exporting NoDL .xml files:

sudo apt-get install ros-<ros2_distro>-ament-nodl

Configuration

Add to package.xml:

<depend>ament_nodl</depend>

Add to CMakeLists.txt:

find_package(ament_nodl REQUIRED)

nodl_export_node_description_file(<package_name>.nodl.xml)

Usage

Create a file called “.nodl.xml" in the same folder as your project's CMakeLists.txt. Include in this file the interface description for each node in the package. Node attributes can be `parameter`, `topic`, `service` or `action`.

Valid values for the topic role tag are: publisher, subscription, or both. Valid values for the service role tag are: server, client, or both. Valid values for the action role tag are: server, client, or both. Types can have custom names.

Example

<interface version="1">
	<node name="<node1_name>" executable="<executable_name>">
		<parameter name="rate" type="int" />
		<topic name="/foo/bar" type="std_msgs/msg/String" role="subscription" />
		<service name="/example_service" type="std_srvs/srv/Empty" role="client" />
		<action name="/example_action" type="example_interfaces/action/Fibonacci" role="both" />
	</node>
	<node name="<node2_name>" executable="<executable_name>">
		...
	</node>
</interface>

CLI

See available verbs on the ROS 2 command line tools for NoDL repo.