problem.js

const hyperdb = require('hyperdb')
const ram = require('random-access-memory')

function create (key, opts) {
  opts = opts || {valueEncoding: 'utf-8'}
  return hyperdb(ram, key, opts)
}

function replicate (a, b, opts) {
  opts = opts || {live: true}
  var stream = a.replicate(opts)
  return stream.pipe(b.replicate(opts)).pipe(stream)
}

const a = create()
let b = null
a.ready(() => {
  console.log('a is ready')
  a.put('hello', 'world', null, (err) => {
    if (err) return console.error(err)
    console.log('hello world written to a')
    b = create(a.key)
    b.ready(onB)
  })
})

function onB (err) {
  if (err) return console.error(err)
  console.log('b is ready')
  replicate(a, b)
  // throws an error somewhere here (while replication) - I guess the message header is invalid
  // either "Remote sent invalid feed message", "Remote message is larger than 8MB (max allowed)" or
  // "Only 128 feeds currently supported"
  b.get('hello', null, (err, data) => {
    if (err) return console.err(err)
    console.log(data[0].value)
  })
}