nros C++ API

Lightweight ROS 2 client library for embedded real-time systems — freestanding C++14 surface that mirrors rclcpp.

Quick Start

#include <nros/nros.hpp>
#include "std_msgs.hpp"  // generated by nano_ros_generate_interfaces()
 
int main() {
    // 1. Initialise the global session.
    NROS_TRY(nros::init("tcp/127.0.0.1:7447"));
 
    // 2. Create a node.
    nros::Node node;
    NROS_TRY(nros::create_node(node, "cpp_talker"));
 
    // 3. Create a typed publisher.
    nros::Publisher<std_msgs::msg::Int32> pub;
    NROS_TRY(node.create_publisher(pub, "/chatter"));
 
    // 4. Publish messages.
    std_msgs::msg::Int32 msg{};
    for (int i = 0; nros::ok() && i < 10; ++i) {
        msg.data = i;
        pub.publish(msg);
        nros::spin(1000);
    }
 
    nros::shutdown();
    return 0;
}

See Getting Started for the full walkthrough.

API Modules

The C++ API is organised into the following module groups (see the Modules tab in the sidebar for each group's contents):

Group	Description
init	Library initialisation, global session, nros::ok()
node	Node creation and lifecycle (nros::Node)
pubsub	Publishers and subscriptions (nros::Publisher<M>, nros::Subscription<M>)
service	Service servers and clients (nros::Service<S>, nros::Client<S>)
action	Action servers and clients (nros::ActionServer<A>, nros::ActionClient<A>)
executor	Callback dispatch, timers, guard conditions
clock	Monotonic and wall-clock time
qos	Quality-of-Service settings
errors	Error codes, nros::Result, NROS_TRY
support	Span, FixedString, FixedSequence, std_compat

Header Organisation

Include the umbrella header for the full surface:

#include <nros/nros.hpp>

Or include only the per-module headers you need (<nros/publisher.hpp>, <nros/subscription.hpp>, …) for faster compile times in large projects.

Concepts

• The Message-Type Concept — what a generated message type M must provide (TYPE_NAME, TYPE_HASH, ffi_publish, …)
• Error Codes — return codes, nros::Result, and recovery guidance

Guides

• Getting Started — project setup, CMake integration, code generation
• Configuration — environment variables and buffer tuning
• ROS 2 Interoperability — interoperability with standard ROS 2 nodes via rmw_zenoh
• Troubleshooting — common issues and solutions

Freestanding vs <tt>std</tt>

By default nros-cpp is freestanding C++14: no STL, no exceptions, no RTTI. Define NROS_CPP_STD before including <nros/nros.hpp> to enable std::string, std::function, and std::chrono convenience overloads on host platforms.