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https://github.com/fluencelabs/js-libp2p
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Merge pull request #102 from libp2p/docs/discovery-example
docs(examples): Peer Discovery Mechanisms 1, 2 and 3
This commit is contained in:
David Dias
GitHub
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58
examples/discovery-mechanisms/1.js
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58
examples/discovery-mechanisms/1.js
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'use strict'
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const libp2p = require('libp2p')
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const TCP = require('libp2p-tcp')
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const Multiplex = require('libp2p-multiplex')
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const SECIO = require('libp2p-secio')
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const PeerInfo = require('peer-info')
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const Railing = require('libp2p-railing')
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const waterfall = require('async/waterfall')
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// Find this list at: https://github.com/ipfs/js-ipfs/blob/master/src/core/runtime/config-nodejs.json
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const bootstrapers = [
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'/ip4/104.131.131.82/tcp/4001/ipfs/QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ',
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'/ip4/104.236.176.52/tcp/4001/ipfs/QmSoLnSGccFuZQJzRadHn95W2CrSFmZuTdDWP8HXaHca9z',
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'/ip4/104.236.179.241/tcp/4001/ipfs/QmSoLPppuBtQSGwKDZT2M73ULpjvfd3aZ6ha4oFGL1KrGM',
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'/ip4/162.243.248.213/tcp/4001/ipfs/QmSoLueR4xBeUbY9WZ9xGUUxunbKWcrNFTDAadQJmocnWm',
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'/ip4/128.199.219.111/tcp/4001/ipfs/QmSoLSafTMBsPKadTEgaXctDQVcqN88CNLHXMkTNwMKPnu',
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'/ip4/104.236.76.40/tcp/4001/ipfs/QmSoLV4Bbm51jM9C4gDYZQ9Cy3U6aXMJDAbzgu2fzaDs64',
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'/ip4/178.62.158.247/tcp/4001/ipfs/QmSoLer265NRgSp2LA3dPaeykiS1J6DifTC88f5uVQKNAd',
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'/ip4/178.62.61.185/tcp/4001/ipfs/QmSoLMeWqB7YGVLJN3pNLQpmmEk35v6wYtsMGLzSr5QBU3',
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'/ip4/104.236.151.122/tcp/4001/ipfs/QmSoLju6m7xTh3DuokvT3886QRYqxAzb1kShaanJgW36yx'
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]
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class MyBundle extends libp2p {
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constructor (peerInfo) {
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const modules = {
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transport: [new TCP()],
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connection: {
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muxer: [Multiplex],
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crypto: [SECIO]
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},
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discovery: [new Railing(bootstrapers)]
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}
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super(modules, peerInfo)
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}
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}
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let node
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waterfall([
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(cb) => PeerInfo.create(cb),
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(peerInfo, cb) => {
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peerInfo.multiaddrs.add('/ip4/0.0.0.0/tcp/0')
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node = new MyBundle(peerInfo)
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node.start(cb)
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}
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], (err) => {
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if (err) { throw err }
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node.on('peer:discovery', (peer) => {
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console.log('Discovered:', peer.id.toB58String())
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node.dial(peer, () => {})
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})
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node.on('peer:connect', (peer) => {
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console.log('Connection established to:', peer.id.toB58String())
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})
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})
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50
examples/discovery-mechanisms/2.js
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examples/discovery-mechanisms/2.js
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'use strict'
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const libp2p = require('libp2p')
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const TCP = require('libp2p-tcp')
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const Multiplex = require('libp2p-multiplex')
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const SECIO = require('libp2p-secio')
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const PeerInfo = require('peer-info')
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const MulticastDNS = require('libp2p-mdns')
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const waterfall = require('async/waterfall')
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const parallel = require('async/parallel')
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class MyBundle extends libp2p {
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constructor (peerInfo) {
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const modules = {
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transport: [new TCP()],
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connection: {
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muxer: [Multiplex],
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crypto: [SECIO]
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},
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discovery: [new MulticastDNS(peerInfo, { interval: 1000 })]
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}
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super(modules, peerInfo)
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}
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}
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function createNode (callback) {
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let node
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waterfall([
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(cb) => PeerInfo.create(cb),
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(peerInfo, cb) => {
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peerInfo.multiaddrs.add('/ip4/0.0.0.0/tcp/0')
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node = new MyBundle(peerInfo)
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node.start(cb)
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}
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], (err) => callback(err, node))
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}
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parallel([
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(cb) => createNode(cb),
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(cb) => createNode(cb)
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], (err, nodes) => {
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if (err) { throw err }
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const node1 = nodes[0]
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const node2 = nodes[1]
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node1.on('peer:discovery', (peer) => console.log('Discovered:', peer.id.toB58String()))
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node2.on('peer:discovery', (peer) => console.log('Discovered:', peer.id.toB58String()))
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})
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@ -1,2 +1,161 @@
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# WIP - This example is still in the works
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# Peer Discovery Mechanisms
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A Peer Discovery module enables libp2p to find peers to connect to. Think of these mechanisms as ways to join the rest of the network, as railing points.
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With these system, a libp2p node can both have a set of nodes to always connect on boot (bootstraper nodes), discover nodes through locality (e.g connected in the same LAN) or through serendipity (random walks on a DHT).
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These mechanisms save configuration and enable a node to operate without any explicit dials, it will just work.
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## 1. Bootstrap list of Peers when booting a node
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For this demo, we will connect to IPFS default bootstrapper nodes and so, we will need to support the same set of features those nodes have, that are: TCP, multiplex and SECIO. You can see the complete example at [1.js](./1.js).
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First, we create our libp2p bundle.
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```JavaScript
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class MyBundle extends libp2p {
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constructor (peerInfo) {
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const modules = {
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transport: [new TCP()],
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connection: {
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muxer: [Multiplex],
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crypto: [SECIO]
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},
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discovery: [new Railing(bootstrapers)]
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}
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super(modules, peerInfo)
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}
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}
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```
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In this bundle, we use a `bootstrappers` array listing peers to connect _on boot_. Here is the list used by js-ipfs and go-ipfs.
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```JavaScript
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const bootstrapers = [
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'/ip4/104.131.131.82/tcp/4001/ipfs/QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ',
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'/ip4/104.236.176.52/tcp/4001/ipfs/QmSoLnSGccFuZQJzRadHn95W2CrSFmZuTdDWP8HXaHca9z',
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'/ip4/104.236.179.241/tcp/4001/ipfs/QmSoLPppuBtQSGwKDZT2M73ULpjvfd3aZ6ha4oFGL1KrGM',
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'/ip4/162.243.248.213/tcp/4001/ipfs/QmSoLueR4xBeUbY9WZ9xGUUxunbKWcrNFTDAadQJmocnWm',
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'/ip4/128.199.219.111/tcp/4001/ipfs/QmSoLSafTMBsPKadTEgaXctDQVcqN88CNLHXMkTNwMKPnu',
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'/ip4/104.236.76.40/tcp/4001/ipfs/QmSoLV4Bbm51jM9C4gDYZQ9Cy3U6aXMJDAbzgu2fzaDs64',
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'/ip4/178.62.158.247/tcp/4001/ipfs/QmSoLer265NRgSp2LA3dPaeykiS1J6DifTC88f5uVQKNAd',
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'/ip4/178.62.61.185/tcp/4001/ipfs/QmSoLMeWqB7YGVLJN3pNLQpmmEk35v6wYtsMGLzSr5QBU3',
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'/ip4/104.236.151.122/tcp/4001/ipfs/QmSoLju6m7xTh3DuokvT3886QRYqxAzb1kShaanJgW36yx'
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]
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```
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Now, once we create and start the node, we can listen for events such as `peer:discovery` and `peer:connect`, these events tell us when we found a peer, independently of the discovery mechanism used and when we actually dialed to that peer.
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```
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let node
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waterfall([
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(cb) => PeerInfo.create(cb),
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(peerInfo, cb) => {
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peerInfo.multiaddrs.add('/ip4/0.0.0.0/tcp/0')
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node = new MyBundle(peerInfo)
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node.start(cb)
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}
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], (err) => {
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if (err) { throw err }
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// Emitted when a peer has been found
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node.on('peer:discovery', (peer) => {
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console.log('Discovered:', peer.id.toB58String())
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// Note how we need to dial, even if just to warm up the Connection (by not
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// picking any protocol) in order to get a full Connection. The Peer Discovery
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// doesn't make any decisions for you.
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node.dial(peer, () => {})
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})
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// Once the dial is complete, this event is emitted.
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node.on('peer:connect', (peer) => {
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console.log('Connection established to:', peer.id.toB58String())
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})
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})
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```
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From running [1.js](./1.js), you should see the following:
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```bash
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> node 1.js
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Discovered: QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ
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Discovered: QmSoLnSGccFuZQJzRadHn95W2CrSFmZuTdDWP8HXaHca9z
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Discovered: QmSoLPppuBtQSGwKDZT2M73ULpjvfd3aZ6ha4oFGL1KrGM
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Discovered: QmSoLueR4xBeUbY9WZ9xGUUxunbKWcrNFTDAadQJmocnWm
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Discovered: QmSoLSafTMBsPKadTEgaXctDQVcqN88CNLHXMkTNwMKPnu
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Discovered: QmSoLV4Bbm51jM9C4gDYZQ9Cy3U6aXMJDAbzgu2fzaDs64
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Discovered: QmSoLer265NRgSp2LA3dPaeykiS1J6DifTC88f5uVQKNAd
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Discovered: QmSoLMeWqB7YGVLJN3pNLQpmmEk35v6wYtsMGLzSr5QBU3
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Discovered: QmSoLju6m7xTh3DuokvT3886QRYqxAzb1kShaanJgW36yx
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Connection established to: QmSoLMeWqB7YGVLJN3pNLQpmmEk35v6wYtsMGLzSr5QBU3
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Connection established to: QmSoLer265NRgSp2LA3dPaeykiS1J6DifTC88f5uVQKNAd
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Connection established to: QmSoLV4Bbm51jM9C4gDYZQ9Cy3U6aXMJDAbzgu2fzaDs64
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Connection established to: QmSoLueR4xBeUbY9WZ9xGUUxunbKWcrNFTDAadQJmocnWm
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Connection established to: QmSoLPppuBtQSGwKDZT2M73ULpjvfd3aZ6ha4oFGL1KrGM
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Connection established to: QmSoLju6m7xTh3DuokvT3886QRYqxAzb1kShaanJgW36yx
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Connection established to: QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ
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Connection established to: QmSoLnSGccFuZQJzRadHn95W2CrSFmZuTdDWP8HXaHca9z
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Connection established to: QmSoLSafTMBsPKadTEgaXctDQVcqN88CNLHXMkTNwMKPnu
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```
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## 2. MulticastDNS to find other peers in the network
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For this example, we need `libp2p-mdns`, go ahead and `npm install` it. You can find the complete solution at [2.js](./2.js).
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Update your libp2p bundle to include MulticastDNS.
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```JavaScript
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class MyBundle extends libp2p {
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constructor (peerInfo) {
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const modules = {
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transport: [new TCP()],
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connection: {
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muxer: [Multiplex],
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crypto: [SECIO]
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},
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// We set the interval here to 1 second so that is faster to observe. The
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// default is 10 seconds.
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discovery: [new MulticastDNS(peerInfo, { interval: 1000 })]
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}
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super(modules, peerInfo)
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}
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}
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```
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To observe it working, spawn two nodes.
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```JavaScript
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parallel([
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(cb) => createNode(cb),
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(cb) => createNode(cb)
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], (err, nodes) => {
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if (err) { throw err }
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const node1 = nodes[0]
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const node2 = nodes[1]
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node1.on('peer:discovery', (peer) => console.log('Discovered:', peer.id.toB58String()))
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node2.on('peer:discovery', (peer) => console.log('Discovered:', peer.id.toB58String()))
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})
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```
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If you run this example, you will see a continuous stream of each peer discovering each other.
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```bash
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> node 2.js
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Discovered: QmSSbQpuKrxkoXHm1v4Pi35hPN5hUHMZoBoawEs2Nhvi8m
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Discovered: QmRcXXhtG8vTqwVBRonKWtV4ovDoC1Fe56WYtcrw694eiJ
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Discovered: QmSSbQpuKrxkoXHm1v4Pi35hPN5hUHMZoBoawEs2Nhvi8m
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Discovered: QmRcXXhtG8vTqwVBRonKWtV4ovDoC1Fe56WYtcrw694eiJ
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Discovered: QmSSbQpuKrxkoXHm1v4Pi35hPN5hUHMZoBoawEs2Nhvi8m
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Discovered: QmRcXXhtG8vTqwVBRonKWtV4ovDoC1Fe56WYtcrw694eiJ
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```
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## 3. Where to find other Peer Discovery Mechanisms
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There are plenty more Peer Discovery Mechanisms out there, you can:
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- Find one in [libp2p-webrtc-star](https://github.com/libp2p/js-libp2p-webrtc-star). Yes, a transport with discovery capabilities! This happens because WebRTC requires a rendezvous point for peers to exchange [SDP](https://tools.ietf.org/html/rfc4317) offer, which means we have one or more points that can introduce peers to each other. Think of it as MulticastDNS for the Web, as in MulticastDNS only works in LAN.
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- Any DHT will offer you a discovery capability. You can simple _random-walk_ the routing tables to find other peers to connect to.
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- You can create your own Discovery service, a registry, a list, a radio beacon, you name it!
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