hyperswarm-peer / integration / hello-world / hello.mjs

#!/usr/bin/env node
// Hello World — JS side of the Hyperswarm interop test.
//
// Joins the live public DHT on a shared topic, discovers peers,
// and exchanges messages via protomux "godot-rpc" channel (type 0).
//
// Usage: node hello.mjs [topic]
//   topic defaults to "hello-hyperswarm"

import Hyperswarm from 'hyperswarm'
import Protomux from 'protomux'
import c from 'compact-encoding'
import crypto from 'crypto'

const topicStr = process.argv[2] || 'hello-hyperswarm'
const topicHash = crypto.createHash('sha256').update(topicStr).digest()

console.log(`[hello-js] topic: "${topicStr}"`)
console.log(`[hello-js] topic hash: ${topicHash.toString('hex').slice(0, 16)}...`)
console.log(`[hello-js] pid: ${process.pid}`)
console.log(`[hello-js] joining live DHT...\n`)

const swarm = new Hyperswarm()
let seq = 0

swarm.on('connection', (conn, peerInfo) => {
  const pk = peerInfo.publicKey.toString('hex').slice(0, 12)
  console.log(`[connected] peer ${pk} (client=${peerInfo.client})`)

  const mux = Protomux.from(conn)

  const channel = mux.createChannel({
    protocol: 'godot-rpc',
    id: null,
    unique: false
  })

  const msg = channel.addMessage({
    encoding: c.raw,
    onmessage (buf) {
      try {
        const text = buf.toString('utf8')
        console.log(`[recv] ${text}`)
      } catch {
        console.log(`[recv] <binary ${buf.length} bytes>`)
      }
    }
  })

  channel.open()

  const iv = setInterval(() => {
    if (conn.destroyed || channel.closed) {
      clearInterval(iv)
      return
    }
    seq++
    const payload = JSON.stringify({
      from: 'js',
      msg: 'Hello World',
      seq
    })
    msg.send(Buffer.from(payload))
    console.log(`[send] ${payload}`)
  }, 5000)

  conn.on('close', () => {
    clearInterval(iv)
    console.log(`[disconnected] peer ${pk}`)
  })

  conn.on('error', () => {})
})

const discovery = swarm.join(topicHash, { server: true, client: true })
await discovery.flushed()
console.log('[hello-js] topic joined, waiting for peers...\n')

// Graceful shutdown
process.on('SIGINT', async () => {
  console.log('\n[hello-js] shutting down...')
  await swarm.destroy()
  process.exit(0)
})