host-discovery

A simple service which sends messages to a multicast address in JSON format. It is designed to run on multiple hosts to maintain a list of subscribers to the multicast group. That can be useful for creating a distributed service. A filter, represented by the "service" field, can be used to filter messages if other hosts emit packets on the same multicast address. IPv4 and IPv6 are supported.

Installation

npm install host-discovery

How to

Import module

var hostDiscovery = require('host-discovery');

Create instance

var service = new hostDiscovery({
    service: 'test',    // Default to 'all'
    protocol: 'udp4',   // Default to udp4, can be udp6
    port: 60600         // Default to 2900
});

If default options are sufficient for you, you can create an instance like this :

var service = new hostDiscovery();

Or for one option :

var service = new hostDiscovery({
    protocol: 'udp6'    
});

Events

Two events are implemented :

• join for new members of multicast group and service field
• leave for members which has left multicast group

service.on('join', (ip) => { 
    console.log('A new member has joined the group : ' + ip); 
});

service.on('leave', (ip) => { 
    console.log('A member has left the group : ' + ip); 
});

The detection of a leaving host is between 10 and 15 seconds.

Methods

To start the service :

service.start();

To stop the service :

service.stop();

To get active hosts :

service.hosts();

// The result will be :
[ '192.168.0.11': { 
    address: '192.168.0.11',
    hostname: 'test01',
    timestamp: 1463782466523
  },
  '192.168.0.12': { 
    address: '192.168.0.12',
    hostname: 'test02',
    timestamp: 1463782466527
  },
  '192.168.0.13': { 
    address: '192.168.0.13',
    hostname: 'test03',
    timestamp: 1463782466537
  } 
]

Updates

• v1.0.5 : Sometimes, we are doing stupid things. Timestamp field is back and host's desinscription magically works again.
• v1.0.4 : Remove "timestamp" field
• v1.0.3 : Add "address" field
• v1.0.2 : Fix "ReferenceError: os is not defined"
• v1.0.1 : Fix "ReferenceError: util is not defined"
• v1.0.0 : Initial release

Licence

The MIT License (MIT) Copyright (c) 2016 Julien Blanc