rosnodejs

Install

npm install rosnodejs

Start a node

const rosnodejs = require('rosnodejs');
rosnodejs.initNode('/my_node')
.then(() => {
  // do stuff
});

Publish/Subscribe

const nh = rosnodejs.nh;
const sub = nh.subscribe('/chatter', 'std_msgs/String', (msg) => {
  console.log('Got msg on chatter: %j', msg);
});

const pub = nh.advertise('/chatter', 'std_msgs/String');
pub.publish({ data: "hi" });

The advertise function takes an options object as optional third argument:

{
  queueSize: 1,
  latching: false //
  throttleMs: 0
}

If you plan to publish messages right after another in the same function, set throttleMs: -1. Otherwise only the last message will be sent.

Udp transport (Experimental)

const nh = rosnodejs.nh;
const sub = nh.subscribe('/chatter', 'std_msgs/String', (msg) => {
  console.log('Got msg on chatter: %j', msg);
}, {
  transports: ["TCPROS", "UDPROS"],  // specify transports, default ["TCPROS"]
  dgramSize: 1500   // optional: datagram packet size, default: 1500 bytes
});

const pub = nh.advertise('/chatter', 'std_msgs/String');
pub.publish({ data: "hi" });

Services

const service = nh.advertiseService('/add_two_ints', 'beginner_tutorials/AddTwoInts', (req, res) => {
  res.sum = req.a + req.b;
  return true;
});

const client = nh.serviceClient('/add_two_ints', 'beginner_tutorials/AddTwoInts');
client.call({a: 1, b: 2});

Params

nh.setParam('val', 2);
nh.getParam('val')
.then((val) => {
  // do stuff
});

Generating Messages

Messages can be generated in a number of ways depending on the versions of ROS and Node.js you're using.

• catkin - works in ROS Kinetic and later for Node.js v6+.

$ catkin_make
OR
$ catkin build

• loadAllPackages() - One-time "build" call available through rosnodejs for versions of ROS before Kinetic and Node.js v6+. Should be called separately and in advance of processes attempting to use messages.

const rosnodejs = require('rosnodejs');
rosnodejs.loadAllPackages();

• On the fly - all versions of ROS and Node.js 4.5+. When generating on the fly, messages can not be required until the node has initialized.

const rosnodejs = require('rosnodejs');
rosnodejs.initNode('my_node', { onTheFly: true }).then(() => {
  const stdMsgs = rosnodejs.require('std_msgs');
  ...
}

	Pre-Kinetic	Kinetic & Later
Node.js >= v6	loadAllPackages(), on the fly	catkin, loadAllPackages(), on the fly
Node.js < v6	on the fly	on the fly

Using Messages

const sensorMsgs = rosnodejs.require('sensor_msgs');

const image = new sensorMsgs.msg.Image();
const temperature = new sensorMsgs.msg.Temperature({ temperature: 32 });

const SetCameraInfo = sensorMsgs.srv.SetCameraInfo;
const setRequest = new SetCameraInfo.Request();

// messages can be used when advertising/subscribing
const nh = rosnodejs.nh;
const StringMsg = rosnodejs.require('std_msgs').msg.String;
const sub = nh.subscribe('/chatter', StringMsg, (msg) => { ... });
const pub = nh.advertise('/chatter', StringMsg);

const AddTwoInts = rosnodejs.require('beginner_tutorials').srv.AddTwoInts;
const service = nh.advertiseService('/add_two_ints', AddTwoInts, (req, res) => { ... });
const client = nh.serviceClient('/add_two_ints', AddTwoInts);

Actions (Experimental)

const nh = rosnodejs.nh;
const as = new rosnodejs.ActionServer({
  nh,
  type: 'turtle_actionlib/Shape',
  actionServer: '/turtle_shape'
});

as.on('goal', function (goal) {
  goal.setAccepted();
});

as.start();

const ac = new rosnodejs.ActionClient({
  nh,
  type: 'turtle_actionlib/Shape',
  actionServer:'/turtle_shape'
});

ac.sendGoal({edges: 3, radius: 1});

Run the turtlesim example

Start:

roscore
rosrun turtlesim turtlesim_node
rosrun turtle_actionlib shape_server

Then run

node src/examples/turtle.js

or, if you are running an older version of node:

npm run compile
node dist/examples/turtle.js

Catkin-Like

Checkout rosnodejs_examples for a more catkin-inspired take on using rosnodejs.

Inspired By

rosnodejs was inspired by other work that you can learn more about here

• roscpp & rospy
• Robots as web services
• ROSBridge
• roslibjs