Package Exports

tinkerhub-discovery

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (tinkerhub-discovery) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

tinkerhub-discovery

This library contains a standarized API for building discovery mechanisms. It is intended to be used to implement some sort of discovery mechanism, such as those for SSDP and MDNS.

The library is made available via NPM:

npm install tinkerhub-discovery

API

Two basic functionality of a discovery instance is the two events available and unavailable. Listeners can be added as such:

discovery.on('available', service => console.log('Service available', service));
discovery.on('unavailable', service => console.log('Service unavailable', service));

Its also possible to list services that are currently known:

console.log(discovery.services);

All implementations that use this library as a base will have functions to filter and map services. This is useful do things like this:

ssdpDiscovery.filter(service => service.headers['HUE-BRIDGEID'])
    .map(service => {
        service.id = service.headers['HUE-BRIDGEID'];
        return service;
    });

Where all SSDP devices are filtered and then the id is changed to be that of the Philips Hue bridge instead of the normal SSDP id.

Building a custom discovery

There are a few ways to build a custom discovery, with the two main ways being:

Event-based discovery, services are added or removed when changed
Sync-based discovery, services are discovered in bulk

A very basic example would be this discovery that listens for incoming UDP packets and just adds them as services:

const { BasicDiscovery, addService } = require('tinkerhub-discovery');

class CustomDiscovery extends BasicDiscovery {
  static get type() {
    return 'typeForDebug';
  }
    
  constructor() {
    super();
  }

  start() {
    super.start();

    this.socket = dgram.createSocket('udp4');
    this.socket.bind();
    this.socket.on(12345, '224.1.1.1', 'listening', () => )
    this.socket.addMembership('224.1.1.1');
      this.socket.setBroadcast(true);
    });
    this.socket.on('message', msg => {
      // Parse incoming message here
      const service = {
        id: extractSomeSortOfId(msg),
        message: msg
      };

      // Add it to the list of services
      this[addService](service);
    });
  }

  stop() {
    this.socket.destroy();

    super.stop();
  }
}

The above discovery would never remove any services, but extending ExpiringDiscovery would activate time based and remove services based on when they were last seen:

const { ExpiringDiscovery, addService } = require('tinkerhub-discovery');

class CustomDiscovery extends ExpiringDiscovery {
  static get type() {
    return 'typeForDebug';
  }
    
  constructor() {
    super({
      maxStaleTime: 60*1000 /* milliseconds */
    });
  }

  start() {
    super.start();

    this.socket = dgram.createSocket('udp4');
    this.socket.bind();
    this.socket.on(12345, '224.1.1.1', 'listening', () => )
    this.socket.addMembership('224.1.1.1');
      this.socket.setBroadcast(true);
    });
    this.socket.on('message', msg => {
      // Parse incoming message here
      const service = {
        id: extractSomeSortOfId(msg),
        message: msg
      };

      // Add it to the list of services
      this[addService](service);
    });
  }

  stop() {
    this.socket.destroy();

    super.stop();
  }
}