KNoT Cloud library for Node.js

A client side library that provides access to the KNoT Cloud for Node.js applications.

Getting started

Install

npm install --save knot-cloud

Quickstart

KNoTCloud connects to http://host:port using the UUID and token as credentials, respectively. Replace this address with your cloud instance and the credentials with valid ones.

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  try {
    await cloud.connect();
    const devices = cloud.getDevices();
    console.log(devices);
  } catch (err) {
    console.error(err);
  }

  await cloud.close();
}
main();

Methods

constructor(host, port, uuid, token)

Create a client object that will connect to a KNoT Cloud instance.

Arguments

• host String KNoT Cloud instance host name.
• port Number KNoT Cloud instance port.
• uuid String User UUID.
• token String User token.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

connect(): Promise<Void>

Connects to the KNoT Cloud instance.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
}
main();

close(): Promise<Void>

Closes the current connection.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  await cloud.close();
}
main();

getDevices(): Promise<Array>

Gets the devices associated to the connected user.

Result

• devices Array devices registered on the cloud or an empty array. Each device is an object in the following format:
  • id String device ID (KNoT ID).
  • name String device name.
  • online Boolean whether this device is online or not.
  • schema Array schema items, each one formed by:
    • sensor_id Number sensor ID.
    • value_type Number semantic value type (voltage, current, temperature, etc).
    • unit Number sensor unit (V, A, W, W, etc).
    • type_id Number data value type (boolean, integer, etc).
    • name String sensor name.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  console.log(await cloud.getDevices());
  await cloud.close();
}
main();

// [ { online: true,
//    name: 'Door lock',
//    id: '7e133545550e496a',
//    schema: [ [Object], [Object] ] } ]

getDevice(id): Promise<Object>

Gets the device identified by id associated to the connected user.

Argument

• id String device ID (KNoT ID).

Result

• device Object device as described in in getDevices()

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  console.log(await cloud.getDevice('7e133545550e496a'));
  await cloud.close();
}
main();

// { online: true,
//   name: 'Door lock',
//   id: '7e133545550e496a',
//   schema: [ { sensor_id: 1,
//               value_type: 3,
//               unit: 0,
//               type_id: 65521,
//               name: 'Lock' },
//             { sensor_id: 2,
//               value_type: 1,
//               unit: 2,
//               type_id: 9,
//               name: 'Card reader' } ] }

getData(id[,limit, start, finish]): Promise<Array>

Gets the last 10 data items published by the device identified by id.

Arguments

• id String device ID (KNoT ID).
• limit String (Optional) the maximum number of data that you want, default=10 (the value * returns all data)
• start String (Optional) the start date that you want your set of data (format=YYYY/MM/DD HH:MM)
• finish String (Optional) the finish date that you want your set of data (format=YYYY/MM/DD HH:MM)

Result

• data_items Array data items published by the device or an empty array. Each data item is an object in the following format:
  • data Object data published by the device, in the following format:
    • sensor_id Number sensor ID.
    • value String|Boolean|Number value published.
  • timestamp Date moment of publication.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  console.log(await cloud.getData('7e133545550e496a'));
  await cloud.close();
}
main();

// [ { data: { sensor_id: 2, value: 0 },
//     timestamp: '2018-08-25T05:29:43.519Z' },
//   { data: { sensor_id: 1, value: true },
//     timestamp: '2018-08-25T05:29:43.520Z' },
//     ... ]

setData(id, data): Promise<Void>

Sets values to sensors.

Arguments

• id String device ID (KNoT ID).
• data Array array of sensor ID-value pairs, as follows:
  • sensorId Number sensor ID.
  • value String|Boolean|Number value to attribute to the sensor. Strings must be Base64 encoded.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  await cloud.setData('7e133545550e496a', [{ sensorId: 1, value: false }]);
  await cloud.close();
}
main();

requestData(id, sensors): Promise<Void>

Requests the device to publish its current value a set of sensors. The value can be retrieved using getData() or by listening to device updates.

Arguments

• id String device ID (KNoT ID).
• sensors Array an array of sensor IDs (Number).

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  await cloud.requestData('7e133545550e496a', [1]);
  await cloud.close();
}
main();

setMetadata(id, metadata): Promise<Void>

Sets the device metadata. It will update the entire object with the contents of metadata. To update a single item inside metadata, fetch it first, using getDevice().

Arguments

• id String device ID (KNoT ID).
• metadata Any device metadata.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  await cloud.setMetadata('7e133545550e496a', { room: { name: 'Lula Cardoso Ayres', location: 'Tiradentes' } });
  await cloud.close();
}
main();

subscribe(id): Promise<Void>

Subscribes to data published by a device identified by id. To listen to the publish events, register a callback with on().

Argument

• id String device ID (KNoT ID).

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  await cloud.subscribe('7e133545550e496a');
  await cloud.close();
}
main();

on(callback)

Registers a callback to receive device updates after subcribe(). A single callback will receive the updates for all devices the user is subscribed to.

Argument

• callback Function callback called with device updates. Receives:
  • event Object published event, object in the following format:
    • source String device ID (KNoT ID).
    • data Object data published by the device, in the following format:
      • sensor_id Number sensor ID.
      • value String|Boolean|Number value published.
    • timestamp Date moment of publication.

Example

const KNoTCloud = require('knot-cloud');
const cloud = new KNoTCloud(
  'knot-test.cesar.org.br',
  3000,
  '78159106-41ca-4022-95e8-2511695ce64c',
  'd5265dbc4576a88f8654a8fc2c4d46a6d7b85574',
);

async function main() {
  await cloud.connect();
  await cloud.subscribe('7e133545550e496a');
  cloud.on((data) => {
    console.log(data);
  });
}
main();

// { data: { sensor_id: 2, value: 21 },
//   timestamp: '2018-08-25T17:46:41.337Z',
//   source: '7e133545550e496a' }