Added websocket client ping (#30)

Author: andersevenrud

src/config.js

@@ -52,7 +52,8 @@ const defaultConfiguration = {
     }
   },
   ws: {
-    port: null
+    port: null,
+    ping: 30 * 1000
   },
   proxy: [
     /*

src/providers/core.js

@@ -165,6 +165,18 @@ class CoreServiceProvider extends ServiceProvider {
       ws.upgradeReq = ws.upgradeReq || req;
       ws._osjs_client = Object.assign({}, req.session.user);
 
+      const interval = this.core.config('ws.ping', 0);
+
+      const pingInterval = interval ? setInterval(() => {
+        ws.send(JSON.stringify({
+          name: 'osjs/core:ping'
+        }));
+      }, interval) : undefined;
+
+      ws.on('close', () => {
+        clearInterval(pingInterval);
+      });
+
       ws.on('message', msg => {
         try {
           const {name, params} = JSON.parse(msg);