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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 {})

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

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

setTerminalTitle​

set the title of the terminal we are running in

Parameters​

  • title