ac-websocket-stream

websocket-stream

Use HTML5 websockets using the Node Streams API.

Usage

This module works in Node or in Browsers that support WebSockets. You can use browserify to package this module for browser use.

var websocket = require('websocket-stream')
var ws = websocket('ws://echo.websocket.org')
process.stdin.pipe(ws)
ws.pipe(process.stdout)

In the example above ws is a duplex stream. That means you can pipe output to anything that accepts streams. You can also pipe data into streams (such as a webcam feed or audio data).

The underlying WebSocket instance is available as ws.socket.

Options

The available options differs depending on if you use this module in the browser or with node.js. Options can be passed in as the third or second argument - WebSocket(address, [protocols], [options]).

options.browserBufferSize

How much to allow the socket.bufferedAmount to grow before starting to throttle writes. This option has no effect in node.js.

Default: 1024 * 512 (512KiB)

options.browserBufferTimeout

How long to wait before checking if the socket buffer has drained sufficently for another write. This option has no effect in node.js.

Default: 1000 (1 second)

options.objectMode

Send each chunk on its own, and do not try to pack them in a single websocket frame.

Default: false

options.binary

Always convert to Buffer in Node.js before sending. Forces options.objectMode to false.

Default: true

options.perMessageDeflate

We recommend disabling the per message deflate extension to achieve the best throughput.

Default: true on the client, false on the server.

Example:

var websocket = require('websocket-stream')
var ws = websocket('ws://realtimecats.com', {
  perMessageDeflate: false
})

Beware that this option is ignored by browser clients. To make sure that permessage-deflate is never used, disable it on the server.

Other options

When used in node.js see the ws.WebSocket documentation

On the server

Using the ws module you can make a websocket server and use this module to get websocket streams on the server:

var websocket = require('websocket-stream')
var wss = websocket.createServer({server: someHTTPServer}, handle)

function handle(stream, request) {
  // `request` is the upgrade request sent by the client.
  fs.createReadStream('bigdata.json').pipe(stream)
}

We recommend disabling the per message deflate extension to achieve the best throughput:

var websocket = require('websocket-stream')
var wss = websocket.createServer({
  perMessageDeflate: false,
  server: someHTTPServer
}, handle)

function handle(stream) {
  fs.createReadStream('bigdata.json').pipe(stream)
}

You can even use it on express.js with the express-ws library:

const express = require('express');
const expressWebSocket = require('express-ws');
const websocketStream = require('websocket-stream/stream');
const app = express();

// extend express app with app.ws()
expressWebSocket(app, null, {
    // ws options here
    perMessageDeflate: false,
});
 
app.ws('/bigdata.json', function(ws, req) {
  // convert ws instance to stream
  const stream = websocketStream(ws, {
    // websocket-stream options here
    binary: true,
  });

  fs.createReadStream('bigdata.json').pipe(stream);
});
 
app.listen(3000);

Run the tests

Server-side tests

npm test

Client-side tests

First start the echo server by running node test-server.js

Then run npm start and open localhost:9966 in your browser and open the Dev Tools console to see test output.

license

BSD LICENSE