knot-cloud-sdk-js-amqp

A client-side library that provides an AMQP abstraction to the KNoT Cloud for Node.js applications.

Quickstart

Install

npm install --save @cesarbr/knot-cloud-sdk-js-amqp

Run

KNoT Cloud AMQP communicates with a RabbitMQ broker at amqp://<username>:<password>@<hostname>:<port> using <token> as credential to execute the operations. Replace this address with your broker instance and the credentials with valid ones. In addition, the library should be configured with the HTTP address of the API Gateway (knot-babeltower).

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const config = {
  amqp: {
    hostname: 'broker.knot.cloud',
    port: 5672,
    username: 'knot',
    password: 'knot',
    token: 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...', // this is not a valid token!
  },
  http: {
    hostname: 'api.knot.cloud', // API Gateway address
    port: 80,
    protocol: 'http',
  },
};

const client = new Client(config);

const thing = {
  id: 'abcdef1234567890',
  name: 'my-thing',
};

const main = async () => {
  try {
    await client.connect();
    const response = await client.register(thing.id, thing.name);
    console.log('register response:', response);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

Methods

Constructor(config)

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

Arguments

• config Object JSON object with the configuration.
  • amqp Object JSON object with broker properties.
    • hostname String (Optional) RabbitMQ instance hostname. Default: 'localhost'.
    • port Number (Optional) RabbitMQ instance port. Default: 5672.
    • username String (Optional) RabbitMQ instance username. Default: 'knot'.
    • password String (Optional) RabbitMQ instance password. Default: 'knot'.
    • token String (Required) KNoT Cloud user token.
  • http Object JSON object with API Gateway configuration.
    • hostname String API Gateway hostname. Default: 'localhost'.
    • port Number API Gateway port. Default: 80.
    • protocol Number API Gateway protocol. Default: 'http'.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

connect(): Promise<Void>

Connects to a RabbitMQ broker instance.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const main = async () => {
  try {
    await client.connect();
    console.log('successfully connected!');
  } catch (err) {
    console.error(err);
  }
};

main();

close(): Promise<Void>

Closes the current connection with the RabbitMQ broker instance.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const main = async () => {
  try {
    await client.connect();
    await client.close();
    console.log('connection successfully closed');
  } catch (err) {
    console.error(err);
  }
};

main();

register(id, name): Promise<Object>

Registers a new thing. Receives an object containing the registered thing's ID.

Arguments

• id String Thing's ID.
• name String Thing's name.

Result

• device Object JSON object in the following format:
  • id String Thing's ID.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thing = {
  id: 'abcdef1234567890',
  name: 'my-thing',
};

const main = async () => {
  try {
    await client.connect();
    const response = await client.register(thing.id, thing.name);
    console.log('thing successfully registered:', response);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
thing successfully registered:
{
  id: 'abcdef1234567890',
  token: '0d26d2e5-1611-477d-b8d3-46adbb14139a'
}
*/

unregister(id): Promise<Object>

Removes a thing from the cloud.

Arguments

• id String Thing's ID.

Result

• device Object JSON object in the following format:
  • id String Thing's ID.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thing = {
  id: 'abcdef1234567890',
  name: 'my-thing',
};

const main = async () => {
  try {
    await client.connect();
    await client.register(thing.id, thing.name);
    const response = await client.unregister(thing.id);
    console.log('thing successfully unregistered:', response);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
thing successfully unregistered:
{
  id: 'abcdef1234567890'
}
*/

getDevices(): Promise<Object>

List all things registered on cloud.

Result

• devices Object JSON object, containing set of things on cloud.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thing = {
  id: 'abcdef1234567890',
  name: 'my-thing',
};

const main = () => {
  try {
    await client.connect();
    await client.register(thing.id, thing.name);
    const response = client.getDevices();
    console.log('list of things:', response);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
list of things:
{
  devices: [
    {
      id: 'abcdef1234567890',
      name: 'my-thing'
    }
  ]
}
*/

updateConfig(id, config): Promise<Object>

Updates the thing's config.

Arguments

• id String Thing's ID.
• config Array Objects in the following format:
  • sensorId Number Sensor ID.
  • schema JSON Object Schema definition, formed by:
    • typeId Number Semantic value type (voltage, current, temperature, etc).
    • valueType Number Data value type (boolean, integer, etc).
    • unit Number Sensor unit (V, A, W, W, etc).
    • name String Sensor name.
  • event JSON Object Event definition, formed by:
    • change Boolean Enable sending sensor data when its value changes
    • timeSec Number - Optional Time interval in seconds that indicates when data must be sent to the cloud
    • lowerThreshold (Depends on schema's valueType) - Optional Send data to the cloud if it's lower than this threshold
    • upperThreshold (Depends on schema's valueType) - Optional Send data to the cloud if it's upper than this threshold

Result

• device Object JSON object, containing thing's metadata.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thing = {
  id: 'abcdef1234567890',
  name: 'my-thing',
  config: [
    {
      sensorId: 0,
      schema: {
        typeId: 65521,
        valueType: 3,
        unit: 0,
        name: 'bool-sensor',
      },
      event: {
        change: true,
        timeSec: 10,
        lowerThreshold: 1000,
        upperThreshold: 3000,
      },
    },
  ],
};

const main = async () => {
  try {
    await client.connect();
    await client.register(thing.id, thing.name);
    const response = await client.updateConfig(thing.id, thing.config);
    console.log('config successfully updated:', response);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
config successfully updated:
{
  id: 'abcdef1234567890',
  name: 'my-thing',
  config: [{
    sensorId: 0,
    schema: {
      typeId: 65521,
      valueType: 3,
      unit: 0,
      name: 'bool-sensor',
    },
    event: {
      change: true,
      timeSec: 10,
      lowerThreshold: 1000,
      upperThreshold: 3000,
    }
  }]
}
*/

publishData(id, data): Promise<Void>

Publishes thing's data.

Arguments

• id String Thing's ID.
• data Array Data in the following format:
  • sensorId Number Sensor ID.
  • value String|Boolean|Number Sensor value.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thingId = 'abcdef1234567890'; // thing already registered!

const main = async () => {
  try {
    await client.connect();
    await client.on('data', (err, msg) => {
      if (err) {
        console.error(err);
      } else {
        console.log('data published successfully:', msg);
      }
    });
    await client.publishData(thingId, [{ sensorId: 0, value: true }]);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
data published successfully:
{
  id: 'abcdef1234567890',
  data: [
    {
      sensorId: 0,
      value: true
    }
  ]
}
*/

getData(id, sensorIds): Promise<Void>

Requests a thing to publish the current data value of the specified sensor(s).

Arguments

• id String Thing's ID.
• sensorIds Array Sensor IDs to request data from.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thingId = 'abcdef1234567890'; // thing already registered!

const main = async () => {
  try {
    await client.connect();
    await client.on('getData', (err, msg) => {
      if (err) {
        console.error(err);
      } else {
        console.log('data successfully requested:', msg);
      }
    });
    await client.getData(thingId, [0]);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
data successfully requested:
{
  id: 'abcdef1234567890',
  sensorIds: [0]
}
*/

setData(id, data): Promise<Void>

Requests a thing to updates the current data value of the specified sensor(s).

Arguments

• id String Device ID.
• data Array Data items to be published, each one in the following format:
  • sensorId Number Sensor ID.
  • value String|Boolean|Number Sensor value.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thingId = 'abcdef1234567890'; // thing already registered!

const main = async () => {
  try {
    await client.connect();
    await client.on('setData', (err, msg) => {
      if (err) {
        console.error(err);
      } else {
        console.log('setData request successfully sent:', msg);
      }
    }
    await client.setData(thingId, [{ sensorId: 0, value: true }]);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

/*
setData request successfully sent:
{
  id: 'abcdef1234567890',
  data: [{
    sensorId: 0,
    value: true
  }]
}
*/

on(event, callback): Promise<Void>

Registers an event callback handler. See next section for details on events.

Arguments

• name String Event name.
• callback Function Event callback handler.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thingId = 'abcdef1234567890'; // thing already registered!

const main = async () => {
  try {
    await client.connect();
    await client.on('setData', (err, msg) => {
      if (err) {
        console.error(err);
      } else {
        console.log('data.update message sent:', msg);
      }
    });
    await Promise.all(
      [true, false, true].map((value) => {
        return client.publishData(thingId, [{ sensorId: 0, value }]);
      })
    );
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

once(event, callback): Promise<Void>

Registers an callback handler only for next event occurrence. See next section for details on events.

Arguments

• name String Event name.
• callback Function Event callback handler.

Example

const Client = require('@cesarbr/knot-cloud-sdk-js-amqp');

const client = new Client(config);

const thingId = 'abcdef1234567890'; // thing already registered!

const main = async () => {
  try {
    await client.connect();
    await client.once('setData', (err, msg) => {
      if (err) {
        console.error(err);
      } else {
        console.log('data.update message sent:', msg);
      }
    });
    await client.publishData(thingId, [{ sensorId: 0, value: true }]);
    await client.close();
  } catch (err) {
    console.error(err);
  }
};

main();

Events

Events can be listened by registering a handler with on or once methods. The handler will receive two parameters: an object containing the message data and an error indicating if something went wrong (it can be null).

Event: "data"

Triggered when a thing publishes sensor data.

Messages

• id String Thing's ID.
• data Array Data objects in the following format:
  • sensorId Number Sensor ID.
  • value String|Boolean|Number Sensor value.

Example

{
  id: 'abcdef1234567890',
  data: [
    {
      sensorId: 0,
      value: false,
    },
    {
      sensorId: 1,
      35,
    },
  ],
}

Event: "getData"

Triggered when a request for things to publish data is sent.

Message

• id String Thing's ID.
• sensorIds Array Sensor IDs to request data.

Example

{
  id: 'abcdef1234567890',
  sensorIds: [0, 1],
}

Event: "setData"

Triggered when a request for things to update data is sent.

Message

• id String Thing's ID.
• data Array Data objects in the following format:
  • sensorId Number Sensor ID.
  • value String|Boolean|Number Sensor value.

Example

{
  id: 'abcdef1234567890',
  data: [
    {
      sensorId: 0,
      value: false,
    },
    {
      sensorId: 1,
      35,
    },
  ],
}