First Project

One command scaffolds a working multi-node workspace; two more build and run it. C++ and CMake, publishing on your machine, with nothing else running — no router, no daemon, no ROS 2 installation.

This assumes the two-step install is done (nros on your PATH, nros setup native --rmw cyclonedds run once).

Scaffold

nros new my_robot --workspace
cd my_robot

That wrote 21 files — a complete workspace, not a hello-world stub:

my_robot/
├── CMakeLists.txt              # workspace root — names the packages, picks the RMW
└── src/
    ├── talker_pkg/             # a C++ node: publishes std_msgs/Int32 on /chatter
    ├── listener_pkg/           # a C++ node: subscribes to /chatter
    ├── demo_bringup/           # launch file + system.toml — no code
    └── robot_entry/            # the binary: boots the launch topology

What each directory is for is the next chapter, Anatomy of What You Just Built. You don’t need it to run.

Build

cmake -S . -B build -DNANO_ROS_ROOT=<path-to-your-nano-ros-checkout>
cmake --build build

The first configure compiles nano-ros’s runtime into the build tree (~3 minutes); rebuilds are seconds. If you use direnv/activate.sh from the nano-ros checkout, -DNANO_ROS_ROOT can be omitted — the NROS_REPO_DIR env it exports is picked up automatically.

Run

./build/src/robot_entry/robot_entry

Published: 0
Received: 0
Published: 1
Received: 1
Published: 2
Received: 2

One process, two nodes: the talker publishes std_msgs/Int32 on /chatter every 500 ms and the listener prints each one it receives — the interleaved Received: lines are your proof of delivery — exactly as a ROS 2 composition container would run two composable nodes. Ctrl-C stops it.

Why nothing else needed to be running: the default RMW is CycloneDDS, which discovers peers directly — there is no router or daemon in the picture. The zenoh backend (for talking to a ROS 2 system) and XRCE (for the smallest targets) are one page away: Choosing an RMW, and switching is a one-word edit — Switching RMW in Config.

Same thing in Rust

nros new my_rust_robot --workspace --lang rust
cd my_rust_robot
NROS_REPO_DIR=<path-to-nano-ros> nros sync   # Rust-side codegen; once per checkout location
RUST_LOG=info cargo run -p robot_entry

[INFO  talker_pkg] Publishing: 0
[INFO  listener_pkg] I heard: 0
[INFO  talker_pkg] Publishing: 1

(The workspace root is a virtual manifest — cargo run alone has no default binary, so name the entry package with -p robot_entry. The Rust talker ticks at 1 s.)

Same workspace shape, same system.toml, same launch file — only the node implementations and the build tool differ. The extra nros sync step is the Rust-side message codegen; C++ does the equivalent inside CMake, which is why the C++ path doesn’t have it.

If it didn’t work

nros: RMW session open failed on a busy machine usually means the DDS port range on your ROS_DOMAIN_ID is contended — pick another: ROS_DOMAIN_ID=57 ./build/src/robot_entry/robot_entry.
Everything else: Troubleshooting — First 10 Minutes.

Where to go next

Understand the four directories — Anatomy.
Talk to a real ROS 2 system — ROS 2 Interoperability.
Put it on a board — How Integration Works.
Add nodes, parameters, more targets — Project layout and the Multi-Node Projects section.

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