Web-DHT is a demo showing one possible way for running a DHT within the web browser. It does this by utilizing bittorrent-dht as the DHT protococol and peer-relay as the underlying transport.

peer-relay is a p2p message relay that allows for peers to send messages to another without being directly connected to one another. This is possible because peer-relay forms it's own network of peers that it can relay messages through. A dgram-like socket interface is also provided which allows peer-relay to be used by packages that exepct a dgram socket like bittorrent-dht. Check out peer-relay for more info on how it works.

A short snippet on how things are setup under the hood:

var PeerRelay = require('peer-relay')
var DHT = require('bittorrent-dht')

var socket = new PeerRelay.Socket(opts)

var dht = new DHT({
  socket: socket // All communication will go through the PeerRelay socket
})

git clone https://github.com/xuset/web-dht/
cd web-dht
npm install

To start the bootstrap/first peer run:

npm start 8000

This will start a NodeJS peer that accepts connections over WebSocket on port 8000. NodeJS peers support incoming WebSockets connections and optionally incoming WebRTC connections while web browser peers only support incoming WebRTC connections. Both support outgoing WebSocket connections.

To start a web browser peer open the index.html file with your browser either by double clicking or starting your own web server. It will attempt to bootstrap itself by first connecting to ws://localhost:8000. The index.html also provides a basic interface for the DHT by providing the ability to get and put static values in the DHT and also displaying some basic stats for that peer like who the peer is connected to.

Multiple web browser peers can be started by opening index.html in multiple tabs/windows/browsers and they will start to connect to each other.