Sending Uint8Array over PUB/SUB (v4.6.0)

[jean-airoldie]

Hi,
I am trying to figure out how to send an Uint8Array over a PUB/SUB pattern.
Currently, the array I publish differs from the one I receive. Could this be caused
by the fact that the array is not encoded into binary and instead text?

Here is a minimal working example of this issue :

const zmq = require('zeromq')
const { expect }  = require('chai')

const ZMQ_ADDR = 'tcp://127.0.0.1:5000'

let sndArr = new Uint8Array([21,31]);

let pub = zmq.socket('pub');
pub = zmq.socket('pub')
pub.bindSync(ZMQ_ADDR)

let sub = zmq.socket('sub');
sub.connect(ZMQ_ADDR);
sub.subscribe('topic');
sub.on('message', function(topic, message) {
  let recvArr = new Uint8Array(message)
  expect(recvArr.toString()).to.equal(sndArr.toString())
});

pub.send(['topic', sndArr])

Example output :

...
AssertionError: expected [ 50, 49, 44, 51, 49 ] to equal [ 21, 31 ]
...

[jean-airoldie]

Futhermore, if I try converting the Uint8Array to a buffer, the message is never received
by the SUB socket.

Here is a minimal working :

const zmq = require('zeromq')
const { expect }  = require('chai')

const ZMQ_ADDR = 'tcp://127.0.0.1:5000'

let sndArr = new Uint8Array([21,31]);
let buf = Buffer.from(sndArr);

let pub = zmq.socket('pub');
pub = zmq.socket('pub')
pub.bindSync(ZMQ_ADDR)

let sub = zmq.socket('sub');
sub.connect(ZMQ_ADDR);
sub.subscribe('topic');
sub.on('message', function(topic, message) {
  let recvArr = new Uint8Array(message)
  expect(recvArr.toString()).to.equal(sndArr.toString())
});

pub.send(['topic', buf])

This results in the program hanging forever because the message is never received
by the SUB socket.

[jean-airoldie]

I tried using zeromq-ng (I was inspired by this issue) which solved my problem.

Here is a minimal working example :

// subscriber.js
const { expect }  = require('chai')
const zmq = require("zeromq-ng")

let sndArr = new Uint8Array([21,31]);

async function run() {
  const sock = new zmq.Subscriber

  sock.connect("tcp://127.0.0.1:5000")
  sock.subscribe("topic")
  console.log("Subscriber connected to port 5000")

  while (!sock.closed) {
    const [topic, msg] = await sock.receive()
    let recvArr = new Uint8Array(msg)
    expect(recvArr.toString()).to.equal(sndArr.toString())
    console.log("Received valid Uint8Array")
  }
}

run()

// publisher.js
const zmq = require("zeromq-ng")

let sndArr = new Uint8Array([21,31]);
let buf = Buffer.from(sndArr);

async function run() {
  const sock = new zmq.Publisher

  await sock.bind("tcp://127.0.0.1:5000")
  console.log("Publisher bound to port 5000")

  while (!sock.closed) {
    console.log("Sending Uint8Array")
    await sock.send(["topic", buf])
    await new Promise(resolve => setTimeout(resolve, 500))
  }
}

run()

Of course, this does not mean that the issue was fixed, rather that I will use zeromq-ng until it is (or until zeromq-ng is integrated into zeromq.js).

[rolftimmermans]

Here is an update: a 6.0 beta has been released that incorporates all changes from ZeroMQ-NG. The API is exactly the same as that of the last ZeroMQ-NG release.

If there are any specific problems remaining please open a new issue!