Solution * Output.md

Solution *

This is the output we expect and should be the same regardless of any solution. Note that WSRewriter and ProxySocket receive different values and the client receives only one message.

Dashboard Server

> node streams.js
Solution *
WSRewriter:  <Buffer 61 20 6d 65 73 73 61 67 65 20 66 72 6f 6d 20 74 68 65 20 66 72 6f 6e 74 65 6e 64 0a>
ProxySocket:  <Buffer 41 20 6d 65 73 73 61 67 65 20 66 72 6f 6d 20 57 53 52 65 77 72 69 74 65 72 0a>

Client side

'a message from the frontend' can be thought of as a jupyter message generated client side.

> nc localhost 3000
Solution *
a message from the frontend
A message from the ProxySocket

streams.js

var Transform = require('stream').Transform;

/// Server:

var server = require('net').createServer();

function onConnection(socket) {


  // Simulates our rewriter transform
  var wsRewriter = new Transform();
  wsRewriter._transform = function(chunk, encoding, done) {
    console.log('WSRewriter: ', chunk);
    done(null, 'A message from WSRewriter\n');
  };

  // Simulates the proxy result from
  var proxySocket = new Transform();
  proxySocket._transform = function(chunk, encoding, done) {
    console.log('ProxySocket: ', chunk);
    done(null, 'A message from the ProxySocket\n');
  };
  socket.setEncoding('utf8');

  // // The Situation
  // socket.write('The Situation\n');
  // console.log('The Situation');
  // // api.js
  // socket.pipe(wsRewriter).pipe(socket);
  // // nodejitsue/node-http-proxy/lib/http-proxy/passes/ws-incoming.js
  // proxySocket.pipe(socket).pipe(proxySocket);

  // Solution 1: Ideally we should be able to pass the transformer to nodejitsu
  socket.write('Solution 1\n');
  console.log('Solution 1');
  // nodejitsue/node-http-proxy/lib/http-proxy/passes/ws-incoming.js
  socket.pipe(wsRewriter).pipe(proxySocket).pipe(socket);


  // Solution 2: Not ideal but would still work. Requires we can pass in a non-socket stream to proxy.ws
  //            Don't know exactly where all these pieces would go, but would most likely be partially in api.js
  // socket.write('Solution 2\n');
  // console.log('Solution 2');
  // //  maybe api.js?
  // socket.pipe(wsRewriter);
  // wsRewriter.pipe(proxySocket);
  // proxySocket.pipe(socket);
}

server.on('connection', onConnection);

server.listen(3000);

The Situation Output.md

The Situation

Two things to note here:

1. The WSRewriter and ProxySocket instances get teh same message. This means there is no pipe established between them
2. The client side receives a message from WSRewriter which is incorrect. This message should have gone to the ProxySocket instance. Furthermore, this causes the socket to close because this message is masked , and a server cannot send a masked message to a client.

Dashboard Server

> node streams.js
The Situation
WSRewriter:  <Buffer 61 20 6d 65 73 73 61 67 65 20 66 72 6f 6d 20 74 68 65 20 66 72 6f 6e 74 65 6e 64 0a>
ProxySocket:  <Buffer 61 20 6d 65 73 73 61 67 65 20 66 72 6f 6d 20 74 68 65 20 66 72 6f 6e 74 65 6e 64 0a>

Client side

'a message from the frontend' can be thought of as a jupyter message generated client side.

> nc localhost 3000
The Situation
a message from the frontend
A message from WSRewriter
A message from the ProxySocket