NodeJS

RemoteViz and NodeJS reverse proxy

RemoteViz and NodeJS reverse proxy

Summary

RemoteViz uses WebSocket protocol to make possible the communication between the client and the service. Without any web servers between the client and the RemoteViz service, a WebSocket connection can be established smoothly. However, in production environments, the web page requests are handled by a web server and only the web server port (port 80 by default) is open from the outside in order to guarantee security. To use the same port and domain for the HTTP requests and the Websocket requests, the websocket traffic has to be routed through the web server. This document explains how to configure NodeJS server as reverse proxy to handle web page requests and websocket traffic over the same port and domain.

NodeJS Installation

Please refer to the NodeJS official documentation to install NodeJS:

For Microsoft Windows and Unix systems: http://nodejs.org/download/

NodeJS proxing library

To route websocket traffic, we use the library node-http-proxy. It is an HTTP programmable proxying library that supports websockets for NodeJS server. It is suitable for implementing components such as proxies and load balancers.

For Microsoft Windows and Unix systems: https://github.com/nodejitsu/node-http-proxy

The recommended installation method is via npm: npm install http-proxy

NodeJS Configuration

In the next section, we consider that the NodeJS web server is bound to the public port 80 (non-SSL) or 443 (SSL) and the RemoteViz service is bound to the private port 8080 (behind a firewall). Here is a simple web server (written in NodeJS) used to handle HTTP requests and WebSocket requests. This example uses an automatic detection of the websocket request by examining the HTTP header for the "Upgrade: WebSocket" line. All websocket traffic will be redirected to the RemoteViz service.

Without Secure Sockets Layer (SSL) encryption:

 var http = require('http'),
     fs = require('fs'),
     httpProxy = require('http-proxy'); // This line refers to the node-http-proxy library.
  
 // Route websocket requests to the RemoteViz service
 // Replace "remoteviz_service_ip" by the RemoteViz service IP address
 var proxy = new httpProxy.createProxyServer({
   target: {
     host: 'remoteviz_service_ip',
     port: 8080
   ;}
 });
 
 // Configure the HTTP server to respond to all requests.
 var proxyServer = http.createServer(function (req, res) {
   /* HERE, write your HTTP server logic.
      The following example returns the index.html page to the client.
      if (req.url == '/index.html'){
      var page = fs.readFileSync(__dirname + '/index.html');
      res.writeHead(200, {'Content-Type': 'text/html'});
      res.write(page);
      res.end();
      }
   */
 });
 
 // Listen to the `upgrade` event and proxy the WebSocket requests.
 proxyServer.on('upgrade', function (req, socket, head) {
   proxy.ws(req, socket, head);
 });
 
 // Web server IP address and port; Replace "yourdomain" by your public domain name server (DNS)
 proxyServer.listen(80, "yourdomain");

With Secure Sockets Layer (SSL) encryption:

 var https = require('https'),
     fs = require('fs'),
     httpProxy = require('http-proxy'); // This line refers to the node-http-proxy library.
  
 // Route secure websocket requests to the RemoteViz service
 // Replace "remoteviz_service_ip" by the RemoteViz service IP address
 var proxy = new httpProxy.createProxyServer({
   target: {
     host: 'remoteviz_service_ip',
     port: 8080
   ;}
 });
 
 var options = {
   // Set the path to the private key file
   key:    fs.readFileSync('ssl/ssl-private.key'),
   // Set the path to the public certificate file
   cert:   fs.readFileSync('ssl/ssl-cert.crt'),
   // Set the path to the Intermediate Certificate
   ca:     fs.readFileSync('ssl/CA_Bundle.pem')
 };
 
 // Configure the HTTPS server to respond to all requests.
 var proxyServer = https.createServer(options, function (req, res) {
   /* HERE, write your HTTP server logic.
      The following example returns the index.html page to the client.
      if (req.url == '/index.html'){
      var page = fs.readFileSync(__dirname + '/index.html');
      res.writeHead(200, {'Content-Type': 'text/html'});
      res.write(page);
      res.end();
      }
   */
 });
 
 // Listen to the `upgrade` event and proxy the WebSocket requests.
 proxyServer.on('upgrade', function (req, socket, head) {
   proxy.ws(req, socket, head);
 });
 
 // Web server IP address and port. Replace "yourdomain" by your public domain name server (DNS)
 proxyServer.listen(443, "yourdomain");

HTML Client Configuration

The last step is the modification of the websocket connection address in the HTML client file. In the file index.html, replace the line:

   theRenderArea.connectTo("ws://127.0.0.1:8080/RenderAreaName");

by the line for using non-SSL:

   theRenderArea.connectTo("ws://yourdomain/RemoteViz/RenderAreaName");

or by the line for using SSL:

   theRenderArea.connectTo("wss://yourdomain/RemoteViz/RenderAreaName");