pubsub-swarm

Form a p2p swarm of nodes around a topic and exchange messages.

Background

This module provides a simple pubsub interface on top of an unstructured swarm of peers interested in a common topic string. Distributed pubsub! It's meant to be used as a primitive to build server-less applications without needing to have a deeper understanding of distributed systems.

This module doesn't make guarantees about latencies, nor does it guarantee delivery. Gossip isn't as fast as flooding, but it's a very robust means of propogating data over an unstructured network. If the network is stable message should reach eveyr node, but partitions can occur in the network and bridging peers can drop out at any time.

Messages are cryptographically signed by their creator and given a unique sequence number. This means that a. each incoming message can be verified that it came from its claimed author, and that b. peers will not report duplicate messages (e.g. if two different peers deliver them).

Example

var pubsub = require('pubsub-swarm')
 
var swarm = pubsub('foobar')
 
swarm.on('message', function (msg) {
  console.log('message', msg)
 
  setTimeout(function() { process.exit(0) }, 1000)
})
 
swarm.on('connected', function () {
  swarm.publish({ data: 'hello warld from ' + this.id + '!'})
})

Run two copies of this:

$ node example.js &
$ node example.js &

Running this in two terminals shows the message exchange:

found + connected to peer
message { data: 'hello warld from
WpiDF+5f+HRTrm2JOmNHTPyGlYGpAN3QNNwwsu3RtbY=.ed25519!' }
found + connected to peer
message { data: 'hello warld from
JxafbAD7qjHCpQY+G/2i1B7vMmBlNTC7HEh9GfP+5yY=.ed25519!' }

API

var pubsub = require('pubsub-swarm')

var swarm = pubsub(topic)

Returns a new pubsub swarm interested in the topic topic (string). It will begin searching for other interested peers using the BitTorrent DHT and multicast DNS.

swarm.on('message', function (msg) {})

Emits when a new message has been received by a peer.

swarm.publish(msg)

Publish a message to the rest of the swarm. It will gradually propogate through the swarm using periodic gossip.

Install

With npm installed, run

$ npm install pubsub-swarm

License

ISC