add basic ws functionality

lib/modules/webserver/backend/index.html

@@ -1 +1,29 @@
 Welcome to Embark!
+
+<script>
+
+var ws = new WebSocket("ws://localhost:8000/logs");
+
+ws.onopen = function() {
+  // Web Socket is connected, send data using send()
+  ws.send("Message to send");
+  alert("Message is sent...");
+};
+
+ws.onmessage = function (evt) {
+  var received_msg = evt.data;
+  console.log(received_msg);
+  //alert("Message is received...");
+};
+
+ws.onclose = function() {
+  // websocket is closed.
+  alert("Connection is closed...");
+};
+
+window.onbeforeunload = function(event) {
+  socket.close();
+};
+
+</script>
+

lib/modules/webserver/server.js

@@ -5,6 +5,7 @@ const {canonicalHost, defaultHost, dockerHostSwap} = require('../../utils/host')
 require('http-shutdown').extend();
 var express = require('express');
 let path = require('path');
+var expressWebSocket = require('express-ws');
 
 class Server {
   constructor(options) {
@@ -15,6 +16,7 @@ class Server {
   }
 
   start(callback) {
+    const self = this;
     if (this.server && this.server.listening) {
       this.logger.warn(__("a webserver is already running at") +
                        " " +
@@ -32,6 +34,20 @@ class Server {
     app.use(serve);
     app.use('/backend', serveStatic(path.join(__dirname, 'backend'), {'backend': ['index.html', 'index.htm']}));
 
+    expressWebSocket(app);
+
+    app.ws('/logs', function(ws, req) {
+      self.events.on("log", function(logLevel, logMsg) {
+        console.dir("got message " + logMsg);
+        ws.send(logMsg);
+      });
+      ws.on('message', function(msg) {
+        console.dir("got message");
+        console.dir(msg);
+        ws.send(msg);
+      });
+    });
+
     //app.get('/embark', function (req, res) {
     //  res.send('Welcome to Embark')
     //});

package.json

@@ -44,6 +44,7 @@
     "eth-lib": "^0.2.8",
     "ethereumjs-wallet": "0.6.0",
     "express": "^4.16.2",
+    "express-ws": "^3.0.0",
     "file-loader": "^1.1.5",
     "finalhandler": "^1.1.1",
     "follow-redirects": "^1.2.4",