node hpfeeds3 client

Native hpfeeds3 client for node.js

hpfeeds is a lightweight authenticated publish-subscribe protocol that supports arbitrary binary payloads.

Installation

$ npm install --save node-hpfeeds-client

Example

const Client = require('node-hpfeeds-client');

const hpfeeds = new Client('test.example.com', 10000, 'user', 'abcd');

hpfeeds.on('data', console.log);

hpfeeds.on('error', err => {
  console.error(err)
  hpfeeds.close();
});

hpfeeds.connect(err => {
  if(err) {
    console.error(err);
    return;
  }

  console.log('connected');

  hpfeeds.subscribe('test.channel', () => {

    console.log('subscribed');

    hpfeeds.publish('test', {test: "test"}, () => {
      console.log('published');
      hpfeeds.close();
    });
  });
});

API

Instantiating

Instantiate the hpfeeds client by passing the host to connect to, the port, the user and the secret to the constructor as arguments:

  const Client = require('node-hpfeeds-client')

  const hpfeeds = new Client('testhost.example.com', 10000, 'user', 'secret');

Connecting

To connect call connect([cb]) with an optional callback

  const Client = require('node-hpfeeds-client')

  const hpfeeds = new Client('testhost.example.com', 10000, 'user', 'secret');

  hpfeeds.connect(err => {
    if(err) {
      console.error('unable to connect', err);
      return;
    }
    console.log('connected!');
  });

The callback is also called when an error occurs while connecting.

Subscribing

Use subscribe(channel, [cb]) to subscribe to a channel with hpfeeds server:

  hpfeeds.subscribe('test_channel', () => {
    console.log('subscribed!');
  });

Once subscribed, the incoming messages can be collected via 'data' event.

Publishing

Use publish(channel, payload, [cb]) to publish data to a channel at hpfeeds server:

  hpfeeds.publish('test_channel', {test: 'test'}, () => {
    console.log('ready to publish more data!');
  });

payload can be a string, a buffer or an object. In the latter case it is automatically converted to JSON first.

Disconnecting

Use close([cb]) to disconnect from hpfeeds server

  hpfeeds.close(() => {
    console.log('disconnected!');
  });

Events

'connected'

Emitted when the connection is established and a server info message is received.

callback(err, server_name)

  hpfeeds.on('connected', (err, name) => {
    if(err) {
      console.error(err);
      return;
    }
    console.log('connected to', name);
  });

'data'

Emitted when new data is available in one of the subscribed channels.

callback(channel, data)

  hpfeeds.on('data', (channel, data) => {
    console.log('received ', channel, data);
  });

'end'

Emitted when the remote gracefully closes the connection

callback()

  hpfeeds.on('end', () => {
    console.log('disconnected from htpfeeds broker!');
  });

'close'

Emitted when the hpfeeds socket is closed.

callback()

  hpfeeds.on('close', () => {
    console.log('htpfeeds socket is closed');
  });

'error'

Emitted when an error occurs (including authentication errors)

callback(err)

  hpfeeds.on('error', err => {
    console.error(err);
    hpfeeds.close();
  });

'timeout'

Emitted when the client socket times out because of inactivity

callback(err)

  hpfeeds.on('timeout', err => {
    console.error(err);
    hpfeeds.close();
  });

License

Licensed under MIT License. Copyright 2019 Coldrift Technologies B.V. All rights reserved.

Maintenance and support

Visit the company's website

References

1. Hpfeeds3 Wire Protocol