🧬 Introduction

Presencejs is a JavaScript library that enables the creation of real-time web applications with a secure, low-latency, and high-performance geo-distributed architecture.

Key Features:

• Geo-distributed Architecture: Deploy your real-time backend close to users all over the world for better performance.
• WebTransport Support: WebTransport is an new API that offers low-latency, bidirectional, client-server messaging.
• Secure, low-latency, and high-performance: PresenceJS prioritizes security, speed, and performance for a seamless user experience.
• Real-time and collaborative experience: With PresenceJS, components receive data flow in real time, ensuring fast and reactive UI by offering the flexibility to send either unreliable or reliable data
• Easy to use: PresenceJS is simple to implement, making it an accessible solution for developers.
• Free for self-managed hosting: PresenceJS is free to use for self-managed hosting, making it an affordable choice for projects of any size.

🌟 Showcase

These React Serverless Components are built with presencejs:

👯‍♀️ GroupHug

Live collaborator avatars for multiplayer web apps

• Preview
• Source code: ./components/react/grouphug-react

🥷🏼 Quick Start

1. Add presencejs to your web app

Using npm

$ npm i --save @yomo/presence

Using bun.js

$ bun add @yomo/presence

Using pnpm

$ pnpm i @yomo/presence

Create a Presence instance

import Presence from "@yomo/presence";

// create an instance.
const p = new Presence("https://prsc.yomo.dev", {
  url: process.env.NEXT_PUBLIC_PRESENCE_URL,
  publicKey: process.env.NEXT_PUBLIC_PRESENCE_PUBLIC_KEY,
  id,
  appId: process.env.NEXT_PUBLIC_APP_ID,
  debug: true,
});

p.on("connected", () => {
  console.log("Connected to server: ", p.host);
});

Create Channel

add subscribe to peers online event:

const c = p.joinChannel('group-hug', myState);

c.subscribePeers((peers) => {
    peers.forEach((peer) => {
      console.log(peer + " is online")
    }
});

Broadcast messages to all peers in this channel

const cb = () => {
  const state = document.hidden ? "away" : "online";
  c.broadcast("hidden-state-change", { state });
};
document.addEventListener("visibilitychange", cb);

Subscribe messages from the other peers

const unsubscribe = channel.subscribe(
  "hidden-state-change",
  ({ payload, peerState }) => {
    console.log(`${peerState.id} change visibility to: ${payload}`);
  },
);

2. Start prscd backend service

see prscd

🤹🏻‍♀️ API

Presence

• joinChannel: return a Channel object

Channel

• subscribePeers: observe peers online and offline events.
• broadcast: broadcast events to all other peers.
• subscribe: observe events indicated
• leave: leave from a Channel

🏡 Self-managed hosting

Tutorial: Single node on Digital Ocean

Tutorial: Geo-distributed system on AWS

Tutorial: Geo-distributed system on Azure

License

The MIT License.