y-websocket 🎩

WebSocket Provider for Yjs

The Websocket Provider implements a classical client server model. Clients connect to a single endpoint over Websocket. The server distributes awareness information and document updates among clients.

This repository contains a simple in-memory backend that can persist to databases, but it can't be scaled easily. The y-redis repository contains an alternative backend that is scalable, provides auth*, and can persist to different backends.

The Websocket Provider is a solid choice if you want a central source that handles authentication and authorization. Websockets also send header information and cookies, so you can use existing authentication mechanisms with this server.

• Supports cross-tab communication. When you open the same document in the same browser, changes on the document are exchanged via cross-tab communication (Broadcast Channel and localStorage as fallback).
• Supports exchange of awareness information (e.g. cursors).

Quick Start

Install dependencies

npm i y-websocket

Start a y-websocket server

There are multiple y-websocket compatible backends for y-websocket:

• @y/websocket-server
• hocuspocus

• y-sweet
• y-redis
• ypy-websocket
• pycrdt-websocket
• yrs-warp
• ...

The fastest way to get started is to run the @y/websocket-server backend. This package was previously included in y-websocket and now lives in a forkable repository.

Install and start y-websocket-server:

npm install @y/websocket-server
HOST=localhost PORT=1234 npx y-websocket

Client Code:

import * as Y from 'yjs'
import { WebsocketProvider } from 'y-websocket'

const doc = new Y.Doc()
const wsProvider = new WebsocketProvider('ws://localhost:1234', 'my-roomname', doc)

wsProvider.on('status', event => {
  console.log(event.status) // logs "connected" or "disconnected"
})

Client Code in Node.js

The WebSocket provider requires a WebSocket object to create connection to a server. You can polyfill WebSocket support in Node.js using the ws package.

const wsProvider = new WebsocketProvider('ws://localhost:1234', 'my-roomname', doc, { WebSocketPolyfill: require('ws') })

API

import { WebsocketProvider } from 'y-websocket'

wsProvider = new WebsocketProvider(serverUrl: string, room: string, ydoc: Y.Doc [, wsOpts: WsOpts])

Create a new websocket-provider instance. As long as this provider, or the connected ydoc, is not destroyed, the changes will be synced to other clients via the connected server. Optionally, you may specify a configuration object. The following default values of wsOpts can be overwritten.

wsOpts = {
  // Set this to `false` if you want to connect manually using wsProvider.connect()
  connect: true,
  // Specify a query-string / url parameters that will be url-encoded and attached to the `serverUrl`
  // I.e. params = { auth: "bearer" } will be transformed to "?auth=bearer"
  params: {}, // Object<string,string>
  // You may polyill the Websocket object (https://developer.mozilla.org/en-US/docs/Web/API/WebSocket).
  // E.g. In nodejs, you could specify WebsocketPolyfill = require('ws')
  WebsocketPolyfill: Websocket,
  // Specify an existing Awareness instance - see https://github.com/yjs/y-protocols
  awareness: new awarenessProtocol.Awareness(ydoc),
  // Specify the maximum amount to wait between reconnects (we use exponential backoff).
  maxBackoffTime: 2500
}

wsProvider.wsconnected: boolean

True if this instance is currently connected to the server.

wsProvider.wsconnecting: boolean

True if this instance is currently connecting to the server.

wsProvider.shouldConnect: boolean

If false, the client will not try to reconnect.

wsProvider.bcconnected: boolean

True if this instance is currently communicating to other browser-windows via BroadcastChannel.

wsProvider.synced: boolean

True if this instance is currently connected and synced with the server.

wsProvider.params : boolean

The specified url parameters. This can be safely updated, the new values will be used when a new connction is established. If this contains an auth token, it should be updated regularly.

wsProvider.disconnect()

Disconnect from the server and don't try to reconnect.

wsProvider.connect()

Establish a websocket connection to the websocket-server. Call this if you recently disconnected or if you set wsOpts.connect = false.

wsProvider.destroy()

Destroy this wsProvider instance. Disconnects from the server and removes all event handlers.

wsProvider.on('sync', function(isSynced: boolean))

Add an event listener for the sync event that is fired when the client received content from the server.

wsProvider.on('status', function({ status: 'disconnected' | 'connecting' | 'connected' }))

Receive updates about the current connection status.

wsProvider.on('connection-close', function(WSClosedEvent))

Fires when the underlying websocket connection is closed. It forwards the websocket event to this event handler.

wsProvider.on('connection-error', function(WSErrorEvent))

Fires when the underlying websocket connection closes with an error. It forwards the websocket event to this event handler.

License

The MIT License © Kevin Jahns