zmq

zmq is a fork of deno-jszmq which is a port of jszmq to TypeScript and Deno, whereas jszmq is port of zeromq to Javascript, supporting both browsers and Deno. The library only support the WebSocket transport (ZWS 2.0).

The API of the library is similar to that of zeromq.js.

Compatibility with ZeroMQ

WebSocket transport added to zeromq recently, and it is only available when compiling from source.

Other ports of zeromq, like NetMQ (C#) and JeroMQ (Java) don't yet support the WebSocket transport.

Compatibility with ZWS 1.0, zwssock, JSMQ and NetMQ.WebSockets

The library is currently not compatible with ZWS 1.0 and the implementation of it.

Installation

Directly importing it:

import * as zmq from "https://deno.land/x/zmq/mod.ts";

Or as import-map.json:

"imports": {
  "zmq": "https://deno.land/x/zmq/mod.ts",
}

deno run -A --unstable --importmap=import-map.json

Supported socket types

Following socket types are currently supported:

• Pub
• Sub
• XPub
• XSub
• Dealer
• Router
• Req
• Rep
• Push
• Pull

How to use

Import zmq with one of the following:

import * as zmq from "https://deno.land/x/zmq/mod.ts";

Creating a socket

To create a socket you can either use the socket function, which is compatible with zeromq.js or use the socket type class.

Socket type class:

const dealer = new Dealer();

with socket function:

const dealer = socket("dealer");

Bind

To bind call the bind function:

import { DenoHttpServer, Router } from "zmq";

const router = new Router();
router.bind(new DenoHttpServer("ws://localhost:80"));

You can also provide an http server and bind multiple sockets on the same port:

import { DenoHttpServer, Pub, Rep } from "zmq";

const server = new DenoHttpServer("ws://localhost:80");

const rep = new Rep();
const pub = new Pub();

rep.bind(server, "/reqrep");
pub.bind(server, "/pubsub");

await server.listen();

Sending

To send call the send method and provide with either array or a single frame. Frame can either be Buffer of string, in case of string it would be converted to Buffer with utf8 encoding.

socket.send("Hello"); // Single frame
socket.send(["Hello", "World"]); // Multiple frames
socket.send([Buffer.from("Hello", "utf8")]); // Using Buffer

Receiving

Socket emit messages through the on (and once) methods which listen to message event. Each frame is a parameter to the callback function, all frames are always instances of Buffer.

socket.on("message", (endpoint, msg) => console.log(msg.toString())); // One frame
socket.on(
  "message",
  (endpoint, frame1, frame2) =>
    console.log(frame1.toString(), frame2.toString()),
); // Multiple frames
socket.on(
  "message",
  (endpoint, ...frames) => frames.forEach((f) => console.log(f.toString())),
); // All frames as array

Examples

Push/Pull

This example demonstrates how a producer pushes information onto a socket and how a worker pulls information from the socket.

producer.js

// producer.ts
import { DenoHttpServer, Push } from "zmq";
const server = new DenoHttpServer("ws://localhost:80");
const sock = new Push();

sock.bind(server);

setInterval(function () {
  console.log("sending work");
  sock.send("some work");
}, 500);

worker.js

// worker.ts
import { Pull } from "zmq";
const sock = new Pull();

sock.connect("ws://localhost:80");
console.log("Worker connected");

sock.on("message", function (endpoint, msg) {
  console.log("work: %s", msg.toString());
});

Pub/Sub

This example demonstrates using zmq in a classic Pub/Sub, Publisher/Subscriber, application.

Publisher: pubber.js

// pubber.ts
import { DenoHttpServer, Pub } from "zmq";
const server = new DenoHttpServer("ws://localhost:80");
const sock = new Pub();

sock.bind(server);
console.log("Publisher bound.");

setInterval(function () {
  console.log("sending a multipart message envelope");
  sock.send(["kitty cats", "meow!"]);
}, 500);

Subscriber: subber.js

// subber.ts
import { Sub } from "zmq";

const sock = new Sub();
sock.connect("ws://localhost:80");
sock.subscribe("kitty cats");
console.log("Subscriber connected to port 3000");

sock.on("message", function (endpoint, topic, message) {
  console.log(
    "received a message related to:",
    topic.toString(),
    "containing message:",
    message.toString(),
  );
});