@yomo/presencejs

Introduction

Presencejs is a JavaScript library that allows you to build real-time web applications quickly, the server is built atop of YoMo, which provide secure, low-latency, and high-performance geo-distributed services.

• Secure, low-latency and high-performance
• Real-time experience
• Revalidation on network recovery
• Keep Connected
• Built-in error retry
• TypeScript

...and a lot more.

With presencejs, components will get data flow in real time. Thus, the UI will be always fast and reactive.

Quick Start

1. Add presencejs to your web app

Using npm

$ npm i --save @yomo/presencejs

Using yarn

$ yarn add @yomo/presencejs

Using pnpm

$ pmpm i @yomo/presencejs

For CDN, you can use skypack: https://cdn.skypack.dev/@yomo/presencejs

<script type="module">
    import { Presence } from 'https://cdn.skypack.dev/@yomo/presencejs';
</script>

2. Connect to presence server

The client need to authenticate with YoMo to establish a realtime connection. The following code sample uses a demo YoMo's server(wss://presence.yomo.dev) and public Key to authenticate and print the message Connected to YoMo! when you’ve successfully connected.

How do I get a token?

If you build your application using next.js, then you can use API Routes to get the access token. For example, the following API route pages/api/auth.js returns a json response with a status code of 200:

export default async function handler(req, res) {
    if (req.method === 'GET') {
        const response = await fetch('https://presence.yomo.dev/api/v1/auth', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({
                app_id: process.env.PRESENCE_APP_ID,
                app_secret: process.env.PRESENCE_APP_SECRET,
            }),
        });
        const data = await response.json();
        res.status(200).json(data.data);
    } else {
        // Handle any other HTTP method
    }
}

Response data:

{
    "token": "eyJhbGciOiJIUzI1..."
}

Create a Presence instance.

import { Presence } from '@yomo/presencejs';

// new Presence(host: string, option?: {
//     // Authentication
//     auth?: {
//         // Certification Type
//         type: 'publickey' | 'token',
//         // The public key in your Allegro Mesh project.
//         publicKey?: string,
//         // api for getting access token
//         endpoint?: string,
//     };
//     // The reconnection interval value.
//     reconnectInterval?: number;
//     // The reconnection attempts value.
//     reconnectAttempts?: number;
// }): Presence

// create an instance.
const yomo = new Presence('wss://presence.yomo.dev', {
    auth: {
        // Certification Type
        type: 'token',
        // api for getting access token
        endpoint: '/api/auth',
    },
});

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

3. Subscribe to messages from the server

Call the toRoom('001') function to enter room 001, without it, you are in the default room.The client receives a message with the name online through the on callback function, and can also subscribe to a message with the name mousemove by returning an observable object through on$.

yomo.on('connected', () => {
    // Enter a room
    yomo.toRoom('001');

    // Function to handle response for given event from server
    yomo.on('online', data => {
        console.log('online:', data);
    });

    // Same as the `on` method, returns an observable response
    yomo.on$('mousemove').subscribe(data => {
        console.log('mousemove:', data);
    });

    // If you want to display the latency, you can get the value of the latency like this
    yomo.on('latency', data => {
        const { id, latency, meshId } = data;
        console.log('latency:', latency);
    });
});

4. Send messages to the server

The following example code send a message to the quickstart room with the name online and the contents pixel position. You can use rxjs to get an observable sequence of browser event transitions，then send the data to the signal channel with the name mousemove in room 001 via ofRoom('001', 'mousemove').

import { fromEvent } from 'rxjs';
import { map } from 'rxjs/operators';

const ID = '34a1dbb5-c031-4680-926c-84a789d251e0';

yomo.on('connected', () => {
    // Function for sending data to the server
    yomo.send('online', {
        id: ID,
        x: 10,
        y: 10,
    });

    // Converting browser events into observable sequences.
    const mousemove$ = fromEvent(document, 'mousemove').pipe(
        map(event => {
            return {
                id: ID,
                x: event.clientX,
                y: event.clientY,
            };
        })
    );

    // Sending data streams to the server
    mousemove$.subscribe(yomo.ofRoom('001', 'mousemove'));
});

5. Close a connection

A connection to YoMo can be closed once it is no longer needed.

yomo.close();
yomo.on('closed', () => {
    console.log('Closed the connection');
});

API

Methods of instance	Description	Type
on	Function to handle response for given event from server	on<T>(event: string, cb: (data: T) => void): void
on$	Same as the on method, returns an observable response	on$<T>(event: string): Observable<T>
send	Function for sending data to the server	send<T>(event: string, data: T)
toRoom	Enter a room	toRoom(roomName: string): Presence
ofRoom	Function for sending data streams to the server	ofRoom(roomName: string, event: string)
close	A connection to YoMo can be closed once it is no longer needed.	close(): void

Examples

CursorChat

License

The MIT License.