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    10.148.1 • Public • Published


    uws is a replacement module for ws which allows, but doesn't guarantee (certainly not when paired with Socket.IO), significant performance and memory-usage improvements. This module is specifically only compatible with Node.js and is installed only like so:

    npm install uws

    • uws can use node-gyp and can recompile itself at installation but does not require so.
    • npm installation never fails, but require('uws') will throw if all of the below points hold true:
      • There was no C++11 compiler available at installation.
      • Your system is not an official Tier 1 Node.js platform.

    Keep in mind

    You can't fix a clogged up system by only fixing part of the problem. Swapping to uws can have dramatical effects if your entire pipeline works well. Socket.IO, SocketCluster and other such mass bloat will not give you desired results as those projects already, from the start, are the bottleneck.

    Read more about other horrible Node.js projects here


    uws tries to mimic ws as closely as possible without sacrificing too much performance. In most cases you simply swap require('ws') with require('uws'):

    var WebSocketServer = require('uws').Server;
    var wss = new WebSocketServer({ port: 3000 });
    function onMessage(message) {
        console.log('received: ' + message);
    wss.on('connection', function(ws) {
        ws.on('message', onMessage);
    Deviations from ws

    There are some important incompatibilities with ws though, we aim to be ~90% compatible but will never implement behavior that is deemed too inefficient:

    • Binary data is passed zero-copy as an ArrayBuffer. This means you need to copy it to keep it past the callback. It also means you need to convert it with Buffer.from(message) if you expect a Node.js Buffer.
    • webSocket._socket is not a net.Socket, it is just a getter function with very basic functionalities.
    • webSocket._socket.remote... might fail, you need to cache it at connection.
    • webSocket acts like an EventEmitter with one listener per event maximum.
    • webSocket.upgradeReq is only valid during execution of the connection handler. If you want to keep properties of the upgradeReq for the entire lifetime of the webSocket you better attach that specific property to the webSocket at connection.




    npm i uws@10.148.1





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    • alexhultman