Many to many WebSocket proxy with pluggable routing logic
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multiple clients.test.js


Many to many WebSocket proxy server

There are some WebSocket servers that only support a single connected client at a time.
You may want to connect multiple clients to that same server.
This lets you do that.


  1. Require it var WebSocketProxy = require('ws-multi-proxy').WebSocketProxy
  2. Setup a proxy server var proxy = new WebSocketProxy({ debug:true, webSocketServer:{ port:1234 } })
  3. Open in your browser
  4. Try it out using ws://localhost:1234/proxy/ws://

Advanced Usage: Connect multiple devtool frontends simultaneously

# install the proxy server
npm install ws-multi-proxy

# launch the basic proxy server
node ./node_modules/ws-multi-proxy/index.js 9023 &

# launch a browser with remote webkit inspector server enabled
open -a "Google Chrome Canary" --args --remote-debugging-port=9222 --user-data-dir="$TMPDIR/.chrome-user-data" about:blank

# find the first available debugger socket
DEBUGGER_SOCKET=$(curl -s "http://localhost:9222/json"|grep webSocketDebuggerUrl|cut -d'"' -f4| head -1)

# inspector client 1
open -a "Google Chrome Canary" "$DEBUGGER_SOCKET"

# inspector client 2
open -a "Google Chrome Canary" "$DEBUGGER_SOCKET"

# etc...

Yay, multiple clients connected to the same inspector session at once.

Advanced Usage

ws-multi-proxy is pretty simple wrapper around the ws module's WebSocketServer.

WebSocket connections are just http GET requests sent with some special headers. So, in order to accept WebSocket connections, we need an http server. The WebSocketServer can create one for you or use an existing http server instance if you have one.

Create a new http server

Or using an existing server instance you have lying around

var httpServer = require('http').createServer().listen(1234)

Create a WebSocketServer config

Tell it which server to use

var wssConfig = { server:httpServer }

Create a WebSocketProxy

Tell it which WebSocketServer config to use

var proxy = new WebSocketProxy({ webSocketServer:wssConfig })

Customize the routing logic

By default the mutateDataFrom* methods handle multiple clients by namespacing the message id. You can modify this logic to do whatever you want.

proxy.mutateDataFromServer =
proxy.mutateDataFromClient = function(data, sender, receiver){

  // perform some sort of custom message validation
  if (data.myCustomToken != receiver.myCustomToken)
    return false // don't sent message

  // or maybe augment the message before it is received
  data.value += " lol, augmented value"

  return data

Or keep the existing functionality by monkeypatching.

var oldMutateDataFromClient = proxy.mutateDataFromClient
proxy.mutateDataFromClient = function(data, sender, receiver){

  // some sort of custom message validation
  if (data.myCustomToken != receiver.myCustomToken)
    return false // don't sent message

  return, data, sender, receiver)