@ionic/discover

Ionic Discover

Simple UDP based protocol for service discovery implemented in pure JS. It is not mDNS or bonjour, but it tries to accomplish the same thing.

Spec

It uses a JSON based textual format:

const message = {
  t: now,
  id: this.id,
  name: this.name,
  host: os.hostname(),
  ip: iface.address,
  port: this.port
};
return 'ION_DP' + JSON.stringify(message);

• t: unix timestamp in second
• id: unique id for this session
• name: name of the announced service
• host: hostname of the machine announcing the service
• ip: ipv4 address
• port: tcp port of the announced service

Why?

Complexity of mDNS and lack of good pure JS implementations. We tried different NPM packages that implemented mDNS, ZeroConf or Bonjour but non of them worked for us:

• mdns: it worked very realiably, but required compiling C code with dependencies. It required complicated and different instructions steps for osx, windows and linux
• node-bonjour: buggy
• node-mdns: buggy

We were in a dead end road with the approach and trying to reimplement mDNS by our own was completely out of scope.

Installation

npm install @ionic/discover --save

Usage

const Publisher = require('@ionic/discover').Publisher;
const serviceName = 'Ionic thing!';
const tcpPort = 8100;
const service = new Publisher(serviceName, tcpPort);
service.start();