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Robot and Cloud (node.js)

These classes and functions are available via the @transitive-sdk/utils npm package and are for use in node.js, i.e., on the robot and the cloud.

Example​

const mqtt = require('mqtt');
const { MqttSync, getLogger, getPackageVersionNamespace } =
  require('@transitive-sdk/utils');

// create a logger and set log level
const log = getLogger('main');
log.setLevel('debug');

// Read config.versionNamespace from parent package.json to determine which
// version namespace to use: major, minor, or patch (default).
const version = getPackageVersionNamespace();
log.debug(`using version namespace ${version}`);

const MQTT_HOST = 'mqtt://localhost'; // the mqtt server provided by robot-agent
const mqttClient  = mqtt.connect(MQTT_HOST, {
  // set the clientId as required the agent to identify ourselves
  clientId: `${process.env.npm_package_name}/${version}`,
  // Transitive abuses the username (which is not used as such) to convey
  // additional information, here the full version number (for reporting).
  username: JSON.stringify({
    version: process.env.npm_package_version,
  }),
  password: process.env.PASSWORD, // is set by agent in startPackage.sh
});

mqttClient.once('connect', (connack) => {
  log.debug('connected to mqtt broker', connack);

  const mqttSync = new MqttSync({mqttClient, ignoreRetain: true,
    // Slices off the first N fields of the topic, i.e., our client NS
    // "/org/device/@scope/name/version":
    sliceTopic: 5
  });

  // use mqttSync ..

});

Capability​

Super class for all cloud capabilities.

Parameters​

  • onReady
  • options (optional, default {})

connectToLocalMQTT​

On the robot, connect to the local MQTT broker run by the robot-agent.

fetchURL​

a simple function to fetch a URL

Parameters​

  • url

findPath​

walk up the directory tree until we find a file or directory called basename

Parameters​

  • basename

getLocalMQTTSync​

On the robot, connect to local MQTT broker and create an MQTTSync instance for it. The provided options can be used to override or extend the default MQTTSync options for the robot.

Parameters​

  • options (optional, default {})

getPackageVersionNamespace​

Get from package info the version namespace we should use, e.g., {version: '1.2.3', config.versionNamespace: 'minor'} => '1.2'

importCapability​

Allows you to dynamically import a capability in node.js to use its API there.

Example:

import { importCapability } from '@transitive-sdk/utils';

const run = async () => {
  const rosTool = await importCapability({
    jwt: 'A_VALID_JWT_FOR_THE_ROS-TOOL_CAPABILITY',
  });

  // Use ros-tool to subscribe to the ROS /odom topic on the device of the JWT.
  // Here "subscribe" is a function exported by the ros-tool capability.
  rosTool.subscribe(1, '/odom');

  // print data as it changes in the local cache:
  rosTool.onData(() =>
    console.log(JSON.stringify(
      rosTool.deviceData.ros?.[1]?.messages?.odom?.pose?.pose, true, 2)),
    'ros/1/messages/odom/pose/pose'
  );
};

run();

Parameters​

  • args

registerCatchAll​

Catch all otherwise uncaught errors

setTerminalTitle​

set the title of the terminal we are running in

Parameters​

  • title